Memory string yara for Hancitor

Hunt Hypothesis

This detection identifies Hancitor malware activity by scanning memory strings against specific YARA signatures to uncover known indicators of compromise within Azure Sentinel workloads. Proactively hunting for this behavior is essential because Hancitor often serves as a persistent initial access vector that can facilitate lateral movement and data exfiltration before triggering higher-severity alerts.

YARA Rule

rule hancitor {
	meta:
		description = "Memory string yara for Hancitor"
		author = "J from THL <[email protected]>"
		reference1 = "https://researchcenter.paloaltonetworks.com/2018/02/threat-brief-hancitor-actors/"
		reference2 = "https://www.virustotal.com/#/file/43e17f30b78c085e9bda8cadf5063cd5cec9edaa7441594ba1fe51391cc1c486/"
		reference3 = "https://www.virustotal.com/#/file/d135f03b9fdc709651ac9d0264e155c5580b072577a8ff24c90183b126b5e12a/"
		date = "2018-09-18"
		maltype1 = "Botnet"
		filetype = "memory"

	strings:
		$a = "GUID="	ascii
                $b = "&BUILD="	ascii
                $c = "&INFO="	ascii
                $d = "&IP="	ascii
                $e = "&TYPE=" 	ascii
                $f = "php|http"	ascii
		$g = "GUID=%I64u&BUILD=%s&INFO=%s&IP=%s&TYPE=1&WIN=%d.%d" ascii fullword


	condition:
		5 of ($a,$b,$c,$d,$e,$f) or $g

}

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 7 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the Memory string YARA for Hancitor detection rule, including suggested filters and exclusions:

• Scenario: Legitimate Software Updates via Windows Update or SCCM

  • Context: During scheduled maintenance windows, tools like Microsoft Endpoint Configuration Manager (SCCM) or native Windows Update download and extract installer packages. These installers often contain compressed archives or scripts that match the specific memory signatures of Hancitor’s payload structure (e.g., specific DLL injection patterns or encoded strings) before execution begins.
  • Filter/Exclusion: Create an exclusion for processes running under the TrustedInstaller service account or specific SCCM agent executables (ccmexec.exe) during defined maintenance hours (e.g., 02:00–06:00 local time). Additionally, filter out events where the parent process is UpdateOrchestratorService.

• Scenario: Deployment of Third-Party Antivirus or EDR Agents

  • Context: Security teams frequently deploy updates for endpoint protection suites such as CrowdStrike Falcon, SentinelOne, or Symantec Endpoint Protection. The installation agents often load large memory modules containing signature databases and heuristic engines that share structural similarities with the Hancitor YARA rules, particularly in how they handle dynamic library loading.
  • Filter/Exclusion: Exclude alerts originating from known security vendor process names (e.g., csfalcon.exe, S1Service.exe, Symantec Antivirus.exe). Implement a whitelist based on the file hash of these specific agent binaries to prevent recurring noise during patch cycles.

• Scenario: Execution of PowerShell Administrative Scripts

  • Context: System administrators frequently run complex PowerShell scripts (.ps1) for user provisioning, group policy updates, or inventory collection using