SLVc0deProtectorv061SLV

Hunt Hypothesis

This hypothesis targets the presence of the SLVc0deProtector v0.6.1 malware variant, which is often used to obfuscate malicious payloads and evade static analysis during initial access or lateral movement. Proactively hunting for this specific YARA signature in Azure Sentinel allows the SOC team to identify compromised endpoints or stored artifacts before the protector is unpacked or executed, reducing the dwell time of low-severity threats that may otherwise blend into normal system noise.

YARA Rule

rule SLVc0deProtectorv061SLV
{
      meta:
		author="malware-lu"
strings:
		$a0 = { EB 02 FA 04 E8 49 00 00 00 69 E8 49 00 00 00 95 E8 4F 00 00 00 68 E8 1F 00 00 00 49 E8 E9 FF FF FF 67 E8 1F 00 }
	$a1 = { EB 02 FA 04 E8 49 00 00 00 69 E8 49 00 00 00 95 E8 4F 00 00 00 68 E8 1F 00 00 00 49 E8 E9 FF FF FF 67 E8 1F 00 00 00 93 E8 31 00 00 00 78 E8 DD FF FF FF 38 E8 E3 FF FF FF 66 E8 0D 00 00 00 04 E8 E3 FF FF FF 70 E8 CB FF FF FF 69 E8 DD FF FF FF 58 E8 DD FF FF FF 69 E8 E3 FF FF FF 79 E8 BF FF FF FF 69 83 C4 40 E8 00 00 00 00 5D 81 ED 9D 11 40 00 8D 95 B4 11 40 00 E8 CB 2E 00 00 33 C0 F7 F0 69 8D B5 05 12 40 00 B9 5D 2E 00 00 8B FE AC }

condition:
		$a0 at pe.entry_point or $a1 at pe.entry_point
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 2 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A developer or build engineer executes a custom-compiled C++ application (e.g., DataProcessor.exe) that was packed with UPX or a similar compressor to reduce binary size for distribution. The compression algorithm creates byte patterns that match the SLVc0deProtectorv061SLV signature.

  • Filter/Exclusion: Exclude files located in specific development directories (e.g., C:\Dev\Projects\, C:\Builds\) or exclude binaries where the PEHeader indicates a known packer (UPX, ASPack) and the file size is under 5MB.

• Scenario: An IT administrator runs a legitimate third-party utility like 7-Zip (7z.exe) or WinRAR (WinRAR.exe) to compress large log files or backup archives. The specific version of the archiver contains a code segment that coincidentally matches the YARA rule’s byte sequence.

  • Filter/Exclusion: Exclude known legitimate archiving tools by their specific SHA256 hash or by matching the process name (7z.exe, WinRAR.exe, tar.exe) when the parent process is a command prompt (cmd.exe) or PowerShell (powershell.exe).

• Scenario: A scheduled maintenance job runs a custom PowerShell script that invokes a native .NET assembly (e.g., ReportGenerator.dll) to generate end-of-month financial reports. The assembly was compiled with a specific obfuscator or protector that triggers the rule.

  • Filter/Exclusion: Exclude files with the .dll extension located in the application’s bin or lib directories (e.g., C:\Apps\Finance\bin\) if the parent process is w3wp.exe (IIS) or dotnet.exe, and the file was last modified more than 3