XHider10GlobaL

Hunt Hypothesis

This YARA rule targets the XHider10GlobaL signature, which likely identifies a specific malware variant or obfuscated payload designed to hide its presence on the host. Proactively hunting for this signature in Azure Sentinel allows the SOC team to detect low-severity stealthy threats that may have evaded traditional signature-based detections and established a foothold within the environment.

YARA Rule

rule XHider10GlobaL
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 83 C4 EC 33 C0 89 45 EC B8 54 20 44 44 E8 DF F8 FF FF 33 C0 55 68 08 21 44 44 64 FF 30 64 89 20 8D 55 EC B8 1C 21 44 44 E8 E0 F9 FF FF 8B 55 EC B8 40 [2] 44 E8 8B F5 FF FF 6A 00 6A 00 6A 02 6A 00 6A 01 68 00 00 00 40 A1 40 [2] 44 E8 7E F6 FF FF 50 E8 4C F9 FF FF 6A 00 50 E8 4C F9 FF FF A3 28 [2] 44 E8 CE FE FF FF 33 C0 5A 59 59 64 89 10 68 0F 21 44 44 8D 45 EC E8 F1 F4 FF FF C3 E9 BB F2 FF FF EB F0 E8 FC F3 FF FF FF FF FF FF 0E 00 00 00 63 3A 5C 30 30 30 30 30 30 31 2E 64 61 74 00 }
	$a1 = { 85 D2 74 23 8B 4A F8 41 7F 1A 50 52 8B 42 FC E8 30 00 00 00 89 C2 58 52 8B 48 FC E8 48 FB FF FF 5A 58 EB 03 FF 42 F8 87 10 85 D2 74 13 8B 4A F8 49 7C 0D FF 4A F8 75 08 8D 42 F8 E8 5C FA FF FF C3 8D 40 00 85 C0 7E 24 50 83 C0 0A 83 E0 FE 50 E8 2F FA FF FF 5A 66 C7 44 02 FE 00 00 83 C0 08 5A 89 50 FC C7 40 F8 01 00 00 00 C3 31 C0 C3 90 }

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

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 DevOps engineer uses a custom PowerShell script or a tool like 7-Zip to compress and encrypt a large log file or backup archive using a non-standard extension (e.g., .zip but with specific header bytes that might be misidentified by the YARA rule’s global matching logic).

  • Filter/Exclusion: Exclude files located in designated backup directories (e.g., C:\Backups\, D:\Archives\) or exclude files with known compression extensions (.zip, .7z, .rar) if the YARA rule is overly broad in its entropy or header matching.

• Scenario: An IT administrator runs a legitimate software installer or updater (e.g., setup.exe from a vendor like Adobe, Microsoft, or Chrome) that embeds a hidden PE section or uses a packed executable format that matches the “XHider” signature due to its global byte pattern.

  • Filter/Exclusion: Exclude known trusted installer paths (e.g., C:\Program Files\, C:\Program Files (x86)\) or whitelist specific vendor-signed executables (e.g., setup.exe from Adobe Inc., Microsoft Corporation) based on digital signature and file path.

• Scenario: A scheduled task or service (e.g., vssadmin.exe for Volume Shadow Copies or wbadmin.exe for Windows Backup) creates temporary shadow copy files or backup metadata files that have a file structure resembling the “XHider” pattern, especially if the rule matches on specific global byte sequences found in backup metadata.

  • Filter/Exclusion: Exclude files in the C:\Windows\System32\ directory with known backup-related names (e.g., *.vss, *.bak) or exclude processes with known PIDs associated with backup services (e.g., `