Detect Verclsid in CrowdStrike LogScale
Adversaries may abuse verclsid.exe to proxy execution of malicious code. Verclsid.exe (Extension CLSID Verification Host) is responsible for verifying each shell extension before it is used by Windows Explorer or the Windows Shell. Adversaries can register a malicious COM object under a CLSID and then invoke verclsid.exe with that CLSID to trigger execution. Since verclsid.exe is signed by Microsoft and performs legitimate COM verification activities, it can bypass application control solutions. Hancitor malware is a known user of this technique.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1218 System Binary Proxy Execution
- Sub-technique
- T1218.012 Verclsid
- Canonical reference
- https://attack.mitre.org/techniques/T1218/012/
LogScale Detection Query
// Detect verclsid.exe proxy execution abuse - T1218.012
#event_simpleName = "ProcessRollup2"
| ImageFileName = /(?i)\\verclsid\.exe$/ OR ParentBaseFileName = /(?i)verclsid\.exe$/
| eval HasCLSID = if(match(CommandLine, /\{[0-9A-Fa-f]{8}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{12}\}/), 1, 0)
| eval SuspiciousParent = if(match(ParentBaseFileName, /(?i)(cmd|powershell|wscript|cscript|mshta|winword|excel|outlook)\.exe$/), 1, 0)
| eval ForcedExec = if(match(CommandLine, /(?i)(\x2Fs|\x2Fc)/), 1, 0)
| eval SuspiciousChild = if(match(ParentBaseFileName, /(?i)verclsid\.exe$/) and match(ImageFileName, /(?i)(cmd|powershell|wscript|cscript|mshta)\.exe$/), 1, 0)
| eval RiskScore = HasCLSID + SuspiciousParent + ForcedExec + SuspiciousChild
| where RiskScore > 1 or SuspiciousChild = 1
| table timestamp, ComputerName, UserName, ImageFileName, CommandLine, ParentBaseFileName, ParentCommandLine, HasCLSID, SuspiciousParent, ForcedExec, SuspiciousChild, RiskScore
| sort timestamp descCrowdStrike LogScale (Falcon) query detecting verclsid.exe abuse for COM proxy execution using ProcessRollup2 events. Applies a risk scoring model evaluating CLSID argument presence, suspicious parent process lineage (script interpreters, Office apps), forced execution flags (/s, /c), and suspicious child processes spawned by verclsid.exe. High-risk events (score > 1) or direct child spawn detections are surfaced.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate COM shell extension registration and verification processes triggered by enterprise software deployment tools such as SCCM or Intune during software pushes
- Security vendor products that enumerate and validate COM objects using verclsid.exe as part of host-based integrity checking routines
- Developer workstations running automated COM interop tests or Visual Studio debugging sessions that invoke verclsid.exe to test custom shell extensions
Other platforms for T1218.012
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Verclsid Execution with CLSID Argument
Expected signal: Sysmon Event ID 1: verclsid.exe with /S /C and CLSID in command line. Security Event ID 4688. The process will attempt to load the COM object registered for this CLSID.
- Test 2Verclsid Launched from cmd.exe
Expected signal: Sysmon Event ID 1: cmd.exe then verclsid.exe with ParentImage=cmd.exe. HasCLSID, ForcedExec, and SuspiciousParent all fire.
- Test 3Malicious COM CLSID Registration for Verclsid Abuse
Expected signal: Sysmon Event ID 13 (Registry Value Set): HKCU\Software\Classes\CLSID path with Temp DLL path as data. The COM registration hunting query captures this as a malicious InprocServer32 pointing to a temp directory.
References (5)
- https://attack.mitre.org/techniques/T1218/012/
- https://lolbas-project.github.io/lolbas/Binaries/Verclsid/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.012/T1218.012.md
- https://www.winosbit.com/articles/what-is-verclsid.exe
- https://www.proofpoint.com/us/threat-insight/post/hancitor-goes-dark
Unlock Pro Content
Get the full detection package for T1218.012 including response playbook, investigation guide, and atomic red team tests.