Detect Invalid Code Signature in IBM QRadar
Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool. Code signing provides a level of authenticity on a binary from the developer and a guarantee that the binary has not been tampered with. Adversaries can copy the metadata and signature information from a signed program, then use it as a template for an unsigned program. Files with invalid code signatures will fail digital signature validation checks, but they may appear more legitimate to users and security tools may improperly handle these files. Unlike Code Signing (T1553.002), this activity will not result in a valid signature.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1036 Masquerading
- Sub-technique
- T1036.001 Invalid Code Signature
- Canonical reference
- https://attack.mitre.org/techniques/T1036/001/
QRadar Detection Query
SELECT DATEFORMAT(starttime, 'YYYY-MM-dd HH:mm:ss') AS EventTime,
sourceip,
"hostname",
username,
"filename",
"filepath",
QIDNAME(qid) AS EventName,
"SignatureStatus",
"Signer",
"CommandLine"
FROM events
WHERE LOGSOURCETYPEID IN (65, 1263)
AND QIDNAME(qid) LIKE '%Image Load%'
AND "SignatureStatus" IS NOT NULL
AND "SignatureStatus" NOT LIKE 'Valid'
AND "SignatureStatus" IN ('Invalid', 'Expired', 'Revoked', 'Untrusted')
AND "Signer" IS NOT NULL
AND "Signer" NOT LIKE ''
AND starttime > (NOW() - 86400000)
ORDER BY starttime DESC
LIMIT 500AQL query targeting Sysmon Event ID 7 (Image Load) log sources within QRadar, filtering for image loads where the digital signature is present but in an invalid state (Invalid, Expired, Revoked, or Untrusted). Mirrors the SPL query's logic of finding signed-but-invalid executable loads.
Data Sources
Required Tables
False Positives & Tuning
- Internal proprietary software signed with an enterprise certificate that has since expired and is pending renewal through PKI team
- Security tools or EDR agents that load drivers or libraries with self-signed or test-mode signatures during installation
- Antivirus quarantine handlers or sandboxing tools that intentionally load and analyze binaries with known-bad signature states
Other platforms for T1036.001
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 1Sign Binary with Invalid Self-Signed Certificate
Expected signal: Sysmon Event ID 7: ImageLoaded with SignatureStatus=Untrusted and Signature containing 'Microsoft Corporation'. Process creation event for test_signed.exe.
- Test 2Copy Signature Metadata with SigThief
Expected signal: Sysmon Event ID 1: Process creation for PowerShell examining signature metadata. File creation events for both binaries in temp directory.
- Test 3Execute Binary with Expired Certificate (Simulated)
Expected signal: PowerShell ScriptBlock Logging Event ID 4104 showing certificate creation. Sysmon Event ID 1 for PowerShell process.
References (6)
- https://attack.mitre.org/techniques/T1036/001/
- https://threatexpress.com/blogs/2017/metatwin-borrowing-microsoft-metadata-and-digital-signatures-to-hide-binaries/
- https://github.com/secretsquirrel/SigThief
- https://learn.microsoft.com/en-us/sysinternals/downloads/sigcheck
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1036.001/T1036.001.md
- https://posts.specterops.io/code-signing-certificate-cloning-attacks-and-defenses-6f98657fc6ec
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