Step 5: Post-Incident, Evaluate software update integrity controls across all third-party applications in your environment, particularly those used in sensitive or privileged contexts. This campaign exposes a control gap in CWE-494/CWE-345: absence of cryptographic verification on software update payloads. Map findings to NIST SP 800-53 SI-7 (Software, Firmware, and Information Integrity) and SA-12 (Supply Chain Protection). Update vendor risk assessments for communications and collaboration tools. Require code-signing verification as a procurement requirement for future software acquisitions, particularly for communications and collaboration tools.
Post-Incident
NIST 800-61r3 §4 — Post-Incident Activity
NIST IR-4 (Incident Handling)
NIST IR-8 (Incident Response Plan)
NIST SI-7 (Software, Firmware, and Information Integrity)
NIST SA-12 (Supply Chain Protection)
NIST RA-3 (Risk Assessment)
CIS 2.1 (Establish and Maintain a Software Inventory)
CIS 2.2 (Ensure Authorized Software is Currently Supported)
CIS 7.1 (Establish and Maintain a Vulnerability Management Process)
Compensating Control
Audit all third-party applications in your software inventory (CIS 2.1) for update-channel integrity verification using a manual checklist: for each communication or collaboration tool, verify whether the vendor documents code-signing of update packages and whether your deployment enforces signature validation before execution. Create a YARA rule targeting the CWE-494 pattern — unsigned PE executables written to application installation directories by application-owned processes — and run it weekly via `yara64.exe unsigned_update.yar C:\Program Files\` across managed endpoints. Add a vendor security questionnaire item requiring documented cryptographic update verification (referencing CWE-345 and NIST SI-7) to all future software procurement evaluations, specifically for communications and collaboration tools matching TrueConf's deployment profile.
Preserve Evidence
For the lessons-learned record, preserve: (1) the complete timeline of TrueConf update events from application logs and Windows Event Logs across all affected hosts, reconstructed to show when the hijacked update was first delivered; (2) the software inventory state (CIS 2.1) at the time of the incident — specifically which versions of TrueConf were deployed and whether version management controls were in place; (3) any vendor communications from TrueConf received during the incident, archived to the incident case file, to assess vendor notification timeliness and advisory quality for future vendor risk scoring; (4) the MITRE ATT&CK technique mapping for this campaign — specifically T1195.002 (Supply Chain Compromise: Compromise Software Supply Chain) and T1072 (Software Deployment Tools) — documented as detection gaps to drive new Sigma rule development.