Microsoft Office Click-To-Run Local Privilege Escalation via TOCTOU Race Condition

Executive Summary

This is a time-of-check time-of-use (TOCTOU) race condition in Microsoft Office Click-To-Run. It allows an authorized attacker with local access to elevate their privileges by exploiting timing inconsistencies in the software's permission checks.

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Detection Guidance

Detection of this TOCTOU race condition requires monitoring for unusual privilege escalation patterns in Microsoft Office Click-To-Run processes. Check for unexpected changes in user permissions or system files modified by Office processes. Review Windows Event Logs for Event ID 4688 (process creation) and 4672 (special privileges assigned).

Commands to check: 'wevtutil qe System /q:"*[System[EventID=4688]]" /c:100' for recent process creations and 'whoami /priv' to list current privileges.

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Impact Analysis

An attacker could gain higher privileges on your system, potentially allowing them to install malicious software, access sensitive data, or perform unauthorized actions. This requires the attacker to already have some level of authorized access.

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Compliance Impact

This vulnerability allows local privilege escalation, which could enable unauthorized access to sensitive data or systems. Such access may violate compliance requirements under GDPR (data protection) or HIPAA (health information security) by exposing personal or protected health information.

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Mitigation Strategies

Apply the latest Microsoft Office security updates immediately through Windows Update or Microsoft Update. Disable unnecessary privileges for Office applications via Group Policy. Monitor for suspicious activity in Office processes and restrict local admin rights where possible.

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