349. Adversaries Masquerade Legitimate Executables as Documents to Enable DLL Side-Loading

Hello everyone!

DLL Side-Loading becomes more and more popular among threat actors, who distribute commodity malware, so today we'll look at Hijack Execution Flow: DLL (T1574.001).

The adversary leveraged a renamed version of FoxitPDFReader.exe to load a malicious msimg32.dll, which starts a chain leading to PureRAT payload. 

The threat actors used various names for the legitimate executable, for example:

Authentic_Job_Application_Form.exe

Project_Salary_Commission_and Benefits.exe

Compensation, Incentives, and Benefits for project participation.exe

Compensation_Benefits_Commission.exe

Digital_Marketing_Proficiency_Test.exe

Salary, Incentives, and Benefits for the Project.exe

Marketing_Performance_Test_Assignment.exe

Commission_Structure.exe

Salary_Incentives_and_Benefits_for_the_Project.exe

Pay_Benefits_Commission_Plan.exe

So, one of hunting opportunities for such activity is to look for FoxitPDFReader.exe with uncommon names:

event_type: "processcreatewin"

AND

proc_file_originalfilename: "FoxitPDFReader.exe"

AND NOT

proc_file_path: "FoxitPDFReader.exe"

See you tomorrow!

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