CVE-2025-21420 Overview
The Windows Disk Cleanup Tool Elevation of Privilege Vulnerability, identified as CVE-2025-21420, is a critical issue in several versions of Microsoft Windows and Windows Server. This local vulnerability allows attackers to gain elevated privileges by exploiting improper permissions handling in the Disk Cleanup Tool.
Critical Impact
Exploiting this vulnerability grants attackers escalated system privileges, allowing them to initiate unauthorized processes and access sensitive data.
Affected Products
- Microsoft Windows 10 1507
- Microsoft Windows 10 1607
- Microsoft Windows 10 1809
Discovery Timeline
- Not Available - Vulnerability discovered by Not Available
- Not Available - Responsible disclosure to Microsoft
- Not Available - CVE CVE-2025-21420 assigned
- Not Available - Microsoft releases security patch
- 2025-02-11 - CVE CVE-2025-21420 published to NVD
- 2025-02-14 - Last updated in NVD database
Technical Details for CVE-2025-21420
Vulnerability Analysis
The vulnerability exists due to incomplete boundary checks in the Windows Disk Cleanup Tool allowing crafted inputs to manipulate privilege levels. This flaw primarily impacts systems where an attacker already has limited access, enabling them to escalate privileges.
Root Cause
The root cause is a symlink race condition within the disk management processes that are not adequately secured, allowing symlink redirection attacks.
Attack Vector
The attack is conducted locally, requiring an attacker to have prior access to the system.
# (Example exploitation code, sanitized)
echo "* * * * * root /usr/bin/exploit_script" >> /etc/crontab
Detection Methods for CVE-2025-21420
Indicators of Compromise
- Unexpected Disk Cleanup Tool invocations
- Unauthorized changes to system configuration files
- Logs indicating permission escalations
Detection Strategies
Utilize SentinelOne to monitor system calls and alert when abnormal activities associated with the Disk Cleanup Tool are detected. Enable notification settings for permission changes.
Monitoring Recommendations
Regularly audit permission levels and utilize event log monitoring to detect unauthorized access attempts to system files and folders.
How to Mitigate CVE-2025-21420
Immediate Actions Required
- Disable the Disk Cleanup Tool until patches can be applied
- Enable enhanced logging for system changes
- Implement GPOs to restrict execution permissions
Patch Information
Refer to Microsoft’s official advisory here for patching instructions.
Workarounds
Utilize OS hardening techniques to restrict access to the Disk Cleanup binaries.
# Configuration example
chmod 640 /path/to/cleanmgr.exe
chown root:trusted_group /path/to/cleanmgr.exe
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
