By Reason Cybersecurity
on Thu May 21 2020
The one that got away
Amidst an expanding background of emerging COVID-19 cyber threats, the Reason Labs research team discovered and reported on a new variant of the Raccoon malware family. Initially discovered back in 2019, the Raccoon malware family is used to steal confidential data and browser information.
The new variant masquerades itself as legit, known program installers.
The new malware sample flew under the AV radar and there were only three minimal detections on VirusTotal over two weeks ago. In this article, we analyze this new variant, its attack methods, and disguise techniques.
This horse is a raccoon
The Raccoon malware family is a Trojan that steals user data from about 60 browsers. The trojan is capable of taking screenshots from the victim machine and capturing input.
The first versions seen, ITW, were written in C++, but a year has gone by and the malware authors have since developed new versions written in Borland Delphi, apparently to make it harder to detect and analyze. The malware comes inside an Inno Setup installer that is responsible for installing both the original program and the malware.
InnoSetup script file – runs regular installation and extracts the malware.
The samples we have imitate benign program installers (I.e. Bandicam, Revo Uninstaller) but hide a Trojan inside them. The installation of the original programs (which are usually cracked versions of programs that have a paid version, so the user knows the installation is not from the original site) will proceed as usual, so the user will not suspect that something suspicious happened. The execution flow of the Trojan installation is very apparent, with alerting command lines and the execution of PowerShell and VBScript, which should have raised alarm bells in all of the security products. However, for some reason, the samples we caught had only three minimal detections on VirusTotal (and as of May 6th, 2020 even 0 detections!). The samples were uploaded to VT more than two weeks ago.
The malware will disable Windows Defender using PowerShell, use VBS to unpack executables from a password protected zip file contained in the installer, and change the registry to disable the admin approval prompt.
The sophisticated network communication remains the same as it was in the first versions: web requests to Google docs (or GitHub) in order to acquire the malware’s CNC IP address. That way the address is not hardcoded in the sample. The first stage is to filter the CNC address from the response and then send base64 encoded params (decodes to bot_id=59407D34-C8C5-44DF-A766-BA8A11CB1CB0_Shayne&config_id=654d0d2e43e786a31eb3ea9dc114b4d91d2014d0&data=null) to “gate/log.php”.
Process tree (the malicious part):
sn.exe file inside data.zip in the installer.
The files contained in the installer.
Extraction of sn.exe from a password protected zip file.
Whole installation script.
Execution flow of:
\cmd.exe /c ”C:\ProgramData\uacb.cmd’
SHA256 of whole samples (not the dropped samples):
About Reason Labs
Reason Labs is the threat research arm of Reason Cybersecurity and we play a leading role in advancing the state of cybersecurity intelligence. We collect raw data about existing and emerging threats from always-on active sensors and then continuously analyze, organize, and add context to evolving cyber activities and attacks in order to deliver actionable insights in real time. This powerful intelligence network leaves Reason prepared to meet threats head-on.
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