hmimysProtectv10

Hunt Hypothesis

This detection identifies potential malicious activity associated with the HmiMyS Protect v10 signature, which may indicate the presence of specific malware or unauthorized software execution within the environment. Proactively hunting for this signal in Azure Sentinel allows the SOC team to validate false positives and uncover early-stage threats that might otherwise remain undetected by standard alerting mechanisms due to its low severity classification.

YARA Rule

rule hmimysProtectv10
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 BA 00 00 00 ?? 00 00 00 00 [2] 00 00 10 40 00 [3] 00 [3] 00 00 [2] 00 [3] 00 [3] 00 [3] 00 [3] 00 [3] 00 ?? 00 00 00 00 00 00 00 [3] 00 00 00 00 00 00 00 00 00 [3] 00 [3] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [3] 00 [3] 00 [3] 00 [3] 00 00 00 00 00 4B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 00 00 56 69 72 74 75 61 6C 46 72 65 65 00 00 00 56 69 72 74 75 61 6C 41 6C 6C 6F 63 00 5E 83 C6 64 AD 50 AD 50 83 EE 6C AD 50 AD 50 AD 50 AD 50 AD 50 E8 E7 07 00 00 AD 8B DE 8B F0 83 C3 44 AD 85 C0 74 32 8B F8 56 FF 13 8B E8 AC 84 C0 75 FB AC 84 C0 74 EA 4E AD A9 }
	$a1 = { E8 BA 00 00 00 ?? 00 00 00 00 [2] 00 00 10 40 00 [3] 00 [3] 00 00 [2] 00 [3] 00 [3] 00 [3] 00 [3] 00 [3] 00 ?? 00 00 00 00 00 00 00 [3] 00 00 00 00 00 00 00 00 00 [3] 00 [3] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [3] 00 [3] 00 [3] 00 [3] 00 00 00 00 00 4B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 00 00 47 65 74 50 72 6F 63 41 64 64 72 65 73 73 00 00 00 56 69 72 74 75 61 6C 46 72 65 65 00 00 00 56 69 72 74 75 61 6C 41 6C 6C 6F 63 00 5E 83 C6 64 AD 50 AD 50 83 EE 6C AD 50 AD 50 AD 50 AD 50 AD 50 E8 E7 07 00 00 AD 8B DE 8B F0 83 C3 44 AD 85 C0 74 32 8B F8 56 FF 13 8B E8 AC 84 C0 75 FB AC 84 C0 74 EA 4E AD A9 00 00 00 }

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

Here are 3-5 specific false positive scenarios for the hmimysProtectv10 detection rule, including suggested filters and exclusions:

• Scenario: The hmi.sys service performs a scheduled nightly integrity scan of the Windows System Volume (C:\Windows\System32).

  • Context: This is a legitimate administrative task where the HMI (Human Machine Interface) protection agent scans core OS files to detect unauthorized modifications.
  • Suggested Filter/Exclusion: Create an exclusion for the process hmiagent.exe when accessing paths under C:\Windows\System32\* during the maintenance window (e.g., 01:00 – 04:00 local time).

• Scenario: A third-party Endpoint Detection and Response (EDR) tool, such as CrowdStrike Falcon or SentinelOne, initiates a real-time file monitor that triggers the YARA rule on new executable drops.

  • Context: The EDR agent creates temporary quarantine files or logs in a shared directory that match the signature pattern of hmimysProtectv10, causing a duplicate alert.
  • Suggested Filter/Exclusion: Exclude alerts generated by process names containing falcon.sys (CrowdStrike) or ss64.exe (SentinelOne) when the file path contains \Temp\ or \Quarantine\.

• Scenario: An automated deployment job using Microsoft SCCM or Ansible Tower pushes a configuration update to the HMI server, temporarily modifying registry keys and protected files.

  • Context: During patch Tuesday or software rollout cycles, the automation tool writes to protected directories, triggering the rule as if it were an unknown modification event.
  • Suggested Filter/Exclusion: Add a process exclusion for `