Detect Component Object Model Hijacking in Google Chronicle
Adversaries may establish persistence by executing malicious content triggered by hijacked references to Component Object Model (COM) objects. COM is a system within Windows to enable interaction between software components through the operating system. References to various COM objects are stored in the Registry. Adversaries can use the COM system to insert malicious code that can be executed in place of legitimate software through hijacking the COM references and relationships as a means for persistence. Hijacking a COM object requires a change in the Windows Registry to replace a reference to a legitimate system component which may cause the execution of the adversary's code instead of the intended COM component.
MITRE ATT&CK
- Tactic
- Privilege Escalation Persistence
- Technique
- T1546 Event Triggered Execution
- Sub-technique
- T1546.015 Component Object Model Hijacking
- Canonical reference
- https://attack.mitre.org/techniques/T1546/015/
YARA-L Detection Query
rule com_object_hijacking_t1546_015 {
meta:
author = "Argus Detection Engineering"
description = "Detects COM object hijacking via suspicious CLSID registry key modifications in HKCU or with suspicious payload paths (T1546.015)"
mitre_attack_tactic = "Persistence"
mitre_attack_technique = "T1546.015"
severity = "HIGH"
priority = "HIGH"
events:
$e.metadata.event_type = "REGISTRY_MODIFICATION"
$e.target.registry.registry_key = /(?i)Classes\\CLSID\\\{[0-9A-Fa-f\-]+\}\\(InprocServer32|LocalServer32|InprocServer|LocalServer|TreatAs|ProgID)/
(
re.regex($e.target.registry.registry_value_data, `(?i)(appdata|\\temp\\|programdata|users\\public|powershell|cmd\.exe|wscript|cscript|mshta|rundll32|regsvr32)`) or
(
re.regex($e.target.registry.registry_key, `(?i)(HKU\\|HKCU\\|Software\\Classes\\CLSID)`) and
not re.regex($e.target.registry.registry_value_data, `(?i)(windows\\system32|syswow64|program files)`)
)
)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting COM hijacking (T1546.015) via registry modifications to CLSID InprocServer32, LocalServer32, TreatAs, and related keys. Triggers on suspicious payload paths (scripting engines, temp directories) or HKCU overrides pointing outside system directories.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise application virtualization solutions (App-V, Citrix) that redirect COM registrations to per-user sandboxed paths
- Legitimate click-to-run Office installations that maintain COM registrations in non-standard user-accessible paths
- Software development SDKs that register test or mock COM components in Temp or AppData during build/test phases
Other platforms for T1546.015
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 1COM Hijack via HKCU InprocServer32
Expected signal: Sysmon Event ID 13: TargetObject=HKCU\SOFTWARE\Classes\CLSID\{BCDE0395-E52F-467C-8E3D-C4579291692E}\InprocServer32, Details=AppData path. IsHkcuOverride=true, IsNotSystemPath=true. Process creation for reg.exe.
- Test 2COM Hijack Targeting Explorer Shell Extension CLSID
Expected signal: Sysmon Event ID 13 for HKCU CLSID registration with Temp directory DLL path. The Temp path is the high-risk indicator.
- Test 3Enumerate COM Hijacking Opportunities
Expected signal: Process creation for powershell.exe with registry enumeration command. Read-only registry access to HKLM and HKCU CLSID trees. Output reveals count of potential hijacking candidates.
References (5)
- https://attack.mitre.org/techniques/T1546/015/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1546.015/T1546.015.md
- https://www.cyberbit.com/blog/endpoint-security/com-hijacking-windows-overlooked-security-vulnerability/
- https://bohops.com/2018/08/18/abusing-the-com-registry-structure-part-2-loading-techniques-for-evasion-and-persistence/
- https://threatexpress.com/blogs/2021/02/living-off-the-com-land/
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