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Cyber Crime Campaign for AppSuite PDF Editor

WatchGuard has recently received reports of a cyber crime campaign underway where a weaponized version of a free PDF editor software “AppSuite PDF Editor” has been distributed to multiple sites for users to unknowingly download and run on their systems. It has been made aware of that the threat actor used Google advertising to promote this software for users to download. 

It was recently observed that the following URL was used to host the malicious file: hxxps[:]//pdfadmin[.]com/productivity/download/90153768[?]cid[=]G4FTU85NWQ9Kc6z3zN where the user would then launch a .msi file named “appsuite-pdf.msi”, or a variation of this filename such as “AppSuite” or “Appsuite”. 

During the installation, the setup will write the below registry key to establish persistence and allows the program to run on start-up:

Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\PDFEditorUpdater

This is done via arguments passed with a --cm switch (PDF Editor.exe --cm=--fullupdate) to instruct the program on how to behave and actions to take, which have been added by the threat actors as part of the weaponized campaign. These callback of actions receive instructions and activate an information stealer referred to as “Tamperedchef” which will begin to collect information on the local system and query web browsers for the purposes of stealing sensitive information. An additional obfuscated .js file is then downloaded to /resources/app/w-electron/bun/releases/ (pdfeditor.js). 

Additional supported arguments for “PDF Editor.exe” include:
--install 
--enableupdate
--disableupdate
--fullupdate
--partialupdate
--backupupdate
--check
--ping
--reboot

It has also been known that the binary elevate.exe will come installed as a bundle, which is a legitimate open source program to assign higher privileges to a program, but which has been customized by the threat actor for the purposes of the campaign to include additional arguments. 

if you are a WatchGuard EPDR customer, you are already protected against this threat thanks to the contextual engine. Either way, be wary of applications from untrusted or official sources like this one.

IOCs:
AppSuite-PDF.msi: 213ECA72F00563FA2ED788A1212C67E0, 0617D54E576E4C124B5F219A79BEE64F

Phishing domain: hxxps[:]//pdfadmin[.]com/productivity/download/90153768[?]cid=G4FTU85NWQ9Kc6z3zN

 

 

Filed under: Malware, Threat Intel