CVE-2024-13962: Local Privilege Escalation in Avast Cleanup Premium

Overview

CVE-2024-13962 is a severe security vulnerability discovered in Gen Digital Inc. Avast Cleanup Premium Version 24.2.16593.17810 on Windows 10 Pro x64. This vulnerability allows local attackers to escalate privileges and execute arbitrary code in the context of the SYSTEM. This privilege escalation vulnerability is particularly concerning as it poses a significant threat to the security of all systems running the affected software worldwide. It has the potential to compromise system integrity and lead to data leakage if not mitigated promptly and correctly.

Vulnerability Summary

CVE ID: CVE-2024-13962
Severity: High, CVSS score of 7.8
Attack Vector: Local
Privileges Required: Low
User Interaction: None
Impact: Privilege escalation, potential system compromise, and data leakage

Affected Products

Product | Affected Versions

Avast Cleanup Premium| Version 24.2.16593.17810 on Windows 10 Pro x64

How the Exploit Works

The vulnerability occurs due to the insecure handling of symbolic links in the TuneupSvc function of the Avast Cleanup Premium software. An attacker can exploit this vulnerability by creating a symbolic link and leveraging a TOCTTOU (time-of-check to time-of-use) attack. Essentially, the software checks the symbolic link at one point and then uses it at a later time, during which an attacker can alter the link. This misstep allows the attacker to escalate their privileges and execute arbitrary code in the context of the SYSTEM, leading to potential system compromise or data leakage.

Conceptual Example Code

The following pseudocode illustrates a conceptual example of how the vulnerability might be exploited:

# Pseudocode for CVE-2024-13962 exploit
def exploit():
# Create a symbolic link
create_symlink('target_link', 'malicious_link')
# Wait for software to check the link
while not is_checked('target_link'):
time.sleep(1)
# Change the symbolic link after the check
change_symlink('target_link', 'malicious_link')
# Execute arbitrary code
execute_code_as_system('malicious_code')

This pseudocode represents the attacker’s actions. The create_symlink function creates a symbolic link, the is_checked function checks if the link has been validated by the software, the change_symlink function changes the symbolic link after validation, and the execute_code_as_system function executes arbitrary code with escalated privileges.
Please note that this is a simplification of the exploit process for illustrative purposes and does not represent an actual working exploit.