Ducktail is a malware family that has been active since the second half of 2021 and aims to steal Facebook business accounts. Kaspersky Daily Iran, WithSecure, and GridinSoft have all covered Ducktail attacks: the infostealer spread under the guise of documents relating to well-known companies’ and brands’ projects and products. The group behind the Ducktail attacks presumably hails from Vietnam. We have analyzed a recent campaign that ran between March and early October 2023 and targeted marketing professionals. An important feature that sets it apart is that, unlike previous campaigns, which relied on .NET applications, this one used Delphi as the programming language.
Infection
The campaign saw the bad actor send out an archive containing images of new products by bona fide companies along with a malicious executable disguised with a PDF icon. When started, the malware would open a real, embedded PDF file that contained the job details. The attack was tailored to target marketing professionals looking for a career change. The choice of victims and the distinctive means used by the threat actor led us to assume early on that the campaign was about spreading a new version of Ducktail.
The malware would install a browser extension capable of stealing Facebook business and ads accounts, likely for subsequent sale.
Ducktail and the malicious extension
We examined a large number of archives from the latest campaign: in each case, a copy of Ducktail was emailed in the name of a major clothing company.
The contents of the malicious archive
If opened by an interested victim, the malicious file saves a PowerShell script named param.ps1 and a PDF decoy locally to C:\Users\Public. The script uses the default PDF viewer on the device to open the decoy, pauses for five minutes, and then terminates the Chrome browser process.
While the script stands by, the parent executable saves a malicious library named libEGL.dll to C:\Users\Public\Libraries\ and then loads it. When launched, the library goes over every LNK file that it finds in C:\ProgramData\Microsoft\Windows\Start Menu\Programs\, C:\ProgramData\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar\, and on the desktop, altering the launch string for all Chromium-based browsers (Google Chrome, Edge, Vivaldi, Brave) by adding the following code: –load-extension=”C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\fjoaledfpmneenckfbpdfhkmimnjocfa”.
Some of the library strings required for the malicious code to run are encrypted with the AES-CBC key “gnghfn47n467n43b” and the initialization vector “dakfhskljh92384h”.
The use of the strings containing the AES key and initialization vector as featured in the code
In addition to launching the library, the parent file saves malicious browser extension files to C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\fjoaledfpmneenckfbpdfhkmimnjocfa. The extension disguises itself with the Google Docs Offline icon and description text, while the directory that features in the path (fjoaledfpmneenckfbpdfhkmimnjocfa) is used by the bona fide extension NordVPN. It is worth noting that other variants of the malware may use different paths to host the extension.
The malicious extension as seen in Google Chrome (left) and the authentic Google Docs Offline extension (right)
The core exception script is obfuscated. It constantly sends the details of all open browser tabs to the command-and-control (C&C) server, and if detecting Facebook-related URLs, checks for ads and business accounts to try and steal them. In particular, the extension snatches cookies and details of accounts that the victim is signed in to on the device. To bypass two-factor authentication, the extension uses Facebook API requests and Vietnam’s 2fa[.]live service, which offers various auxiliaries for generating one-time access codes, among other things. This is probably how the hackers log in after the user’s authentication session has expired. Stolen credentials and cookies are forwarded to a C&C server registered in Vietnam.
Malicious file usage flowchart
In this campaign, in addition to the main script, the malware would save to the extension folder a script named jquery-3.3.1.min.js, a corrupted version of the core script from prior attacks.
DuckTail attack geography
According to our telemetry, cybercriminals most often attacked users in India. Our solutions also stopped infection attempts on devices of users in Kazakhstan, Ukraine, Germany, Portugal, Ireland, Greece, Jordan, Pakistan, Vietnam, UAE, USA, Peru and Chile.
MITRE ATT&CK Matrix
| Tactic | Technique ID | Technique |
| Initial Access | T1566.001 | Phishing: Spearphishing Attachment |
| Persistence | T1176 | Browser Extensions |
| Execution | T1059.001 | Command and Scripting Interpreter: PowerShell |
| T1129 | Shared Modules | |
| T1204.002 | User Execution: Malicious File | |
| Enterprise | T1539 | Steal Web Session Cookie |
| Resource Development | T1583.001 | Acquire Infrastructure: Domains |
| Reconnaissance | T1589 | Gather Victim Identity Information |
| T1598.002 | Phishing for Information: Spearphishing Attachment | |
| Defense Evasion | T1027 | Obfuscated Files or Information |
| Command and Control | T1071.001 | Application Layer Protocol: Web Protocols |
| T1132.001 | Data Encoding: Standard Encoding | |
| Exfiltration | T1041 | Exfiltration Over C2 Channel |
Indicators of compromise
c82b959d43789d3dbf5115629c3c01fa8dd599fbec36df0f4bc5d0371296545a
2b3decf08bf9223fb3e3057b5a477d35e62c0b5795a883ceaa9555ca7c28252f
69257876e2ec5bdbe7114d6ce209f13afbfddb2af0006a6d17e6e91578966870
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bde696a0ae901864716320e3111d5aa49cba3b1d9375dce2903f7433a287b2f2
04dd228d0b088c4116b503c31de22c1746054226a533286bec3a3d0606d73119
89f016d32707f096cc8daf674e5a9fc2ba6cf731d610f5303d997fc848645788
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1117a93b4b4b78e4d5d6bd79f5f0e04926759558218df30e868464f05bf1bd3d
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b9a984383a5825868c23bc3afdc70e3af2a56d26d002431940d2429c8e88ace9
c6ae36e28668c6132da4d08bca7ceb13adf576fa1dbdb0a708d9b3b0f140dd03
d03e1a0fce0b112bba4d56380c8d1be671845dd3ed90ec847635ba6015bad84d
e8cebc5152cd3f7496f0471de5e5af439c15df16827ea296e84fcd5f348b2690
ab95f377bf7ae66d26ae7d0d56b71dec096b026b8090f4c5a19ac677a9ffe047
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1183cd0b8c7f1489f0e3789efa1a7fc07852ec12c6e8964c87d7ad0fd42e2da0
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64f6cbe9adf91bc4ed457c79643d764a130b0d25364817c8b6da17b03ff91aa7
bdf8dea28f91adcba7780a26951abc9c32a4a8c205f3207fd4f349f6db290da7
d4f10bd162ee77f4778ecc156921f5949cd2d64aab45b31d6050f446e59aed5a
bdf8dea28f91adcba7780a26951abc9c32a4a8c205f3207fd4f349f6db290da7
C&C
dauhetdau[.]com
motdanvoi20232023[.]com
voiconprivatesv2083[.]com
cavoisatthu2023asd[.]com
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