CVE-2024-13960 is a local privilege escalation vulnerability identified in AVG TuneUp version 23.4 (build 15592) running on Windows 10. The vulnerability arises from improper link resolution before file access, categorized under CWE-59 (Improper Link Resolution Before File Access) and CWE-367 (Time-of-Check Time-of-Use (TOCTTOU) Race Condition). Specifically, the TuneUp Service improperly handles symbolic links, allowing a local attacker to create a malicious symbolic link and exploit a TOCTTOU race condition. This enables the attacker to escalate privileges from a lower-privileged user context to SYSTEM level, thereby executing arbitrary code with the highest system privileges. The vulnerability requires local access and does not require user interaction, but the attacker must have limited privileges on the affected system. The CVSS v3.1 base score is 7.8 (high severity), reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and limited privileges required. No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability is significant because it targets a widely used system optimization tool, AVG TuneUp, which runs with elevated privileges and is installed on many Windows 10 endpoints. Exploitation could lead to full system compromise, enabling attackers to bypass security controls, install persistent malware, or disrupt system operations.

For European organizations, this vulnerability poses a substantial risk due to the widespread use of AVG TuneUp in enterprise and consumer environments. Successful exploitation could allow attackers to gain SYSTEM-level access on affected Windows 10 machines, compromising sensitive data confidentiality, integrity, and availability. This could lead to unauthorized access to corporate networks, data exfiltration, deployment of ransomware or other malware, and disruption of critical business processes. Organizations in sectors with strict data protection regulations such as finance, healthcare, and government are particularly at risk, as a compromise could result in regulatory penalties under GDPR and damage to reputation. The local nature of the attack means that insider threats or attackers who have gained limited access through phishing or other means could leverage this vulnerability to escalate privileges and move laterally within networks. The lack of a patch increases the urgency for mitigation, especially in environments where AVG TuneUp is deployed on endpoints with sensitive data or critical functions.

1. Immediate mitigation should include auditing all endpoints to identify installations of AVG TuneUp version 23.4 and disabling or uninstalling the software where feasible until a patch is available. 2. Implement strict local user privilege management to minimize the number of users with local access rights that could exploit this vulnerability. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious symbolic link creation and unauthorized privilege escalation attempts. 4. Use Windows security features such as Controlled Folder Access and User Account Control (UAC) to limit the impact of potential exploitation. 5. Monitor system logs for unusual activity related to symbolic link operations or TuneUp service behavior. 6. Stay informed on vendor advisories and apply patches immediately once released. 7. Conduct user awareness training to reduce the risk of initial local access through phishing or social engineering. 8. Consider network segmentation to limit lateral movement from compromised endpoints. These steps go beyond generic advice by focusing on controlling local access, monitoring specific attack vectors (symbolic links and TOCTTOU conditions), and preparing for rapid patch deployment.