311. Hunting for MSBuild Abuse

Hello everyone!

Adversaries love proxy execution. And they can use trusted developer utilities to solve this task. Today we'll look at an example of  Trusted Developer Utilities Proxy Execution: MSBuild (T1127.001).

As always, we need an example. The adversary created a scheduled task to execute a malicious XML file with msbuild.exe:

schtasks /create /tn \Microsoft\Windows\Ras\Outbound /tr "CSIDL_WINDOWS\microsoft.net\framework\v4.0.30319\msbuild.exe c:\programdata\microsoft\rac\outbound\outbound.xml" /sc minute /mo 60 /ru system

We can hunt for msbuild.exe executing files from suspicious folders or with suspicious extensions, for example:

event_type: "processcreatewin"

AND

proc_file_path: "msbuild.exe"

AND

cmdline: "programdata"

See you tomorrow!

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