CVE-2022-1256: McAfee Agent Privilege Escalation Flaw

CVE-2022-1256 Overview

CVE-2022-1256 is a local privilege escalation vulnerability affecting McAfee Agent (MA) for Windows prior to version 5.7.6. This vulnerability allows a local low-privileged user to gain SYSTEM privileges by exploiting the repair functionality. The flaw exists because temporary file actions are performed on the local user's %TEMP% directory with SYSTEM privileges, which can be manipulated through symbolic links.

Critical Impact

A low-privileged local attacker can escalate to SYSTEM privileges on affected Windows systems, potentially leading to complete system compromise, data exfiltration, or further lateral movement within the network.

Affected Products

• McAfee Agent for Windows prior to version 5.7.6
• Systems with McAfee endpoint protection solutions utilizing the vulnerable agent component
• Enterprise environments with centrally managed McAfee deployments

Discovery Timeline

• 2022-04-14 - CVE-2022-1256 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-1256

Vulnerability Analysis

This vulnerability falls into the category of a symlink attack combined with improper privilege management. When the McAfee Agent repair functionality is executed, certain temporary file operations are performed with elevated SYSTEM privileges. The vulnerability arises because these operations target the local user's %TEMP% directory, which is user-controllable.

An attacker with low-level local access can create symbolic links within their %TEMP% directory that redirect write operations to sensitive system locations. When the repair functionality runs with SYSTEM privileges, it follows these symbolic links and performs file operations on arbitrary system paths, effectively allowing the attacker to write or modify files with SYSTEM-level permissions.

Root Cause

The root cause of CVE-2022-1256 involves two CWE weaknesses:

1. CWE-269 (Improper Privilege Management): The repair functionality performs operations with SYSTEM privileges in a user-controllable directory without proper privilege separation or validation.

2. CWE-59 (Improper Link Resolution Before File Access): The application fails to properly validate or resolve symbolic links before performing privileged file operations, allowing path traversal through symlink manipulation.

The combination of these weaknesses creates a classic Time-of-Check to Time-of-Use (TOCTOU) race condition where the attacker can substitute legitimate temporary files with malicious symbolic links between the time the path is checked and when operations are performed.

Attack Vector

The attack requires local access to the system with a low-privileged user account. The attacker does not need any user interaction from administrators or other users to exploit this vulnerability. The attack sequence typically involves:

1. Creating a symbolic link in the user's %TEMP% directory pointing to a privileged system location
2. Triggering the McAfee Agent repair functionality
3. The repair process follows the symbolic link and performs privileged operations on the target location
4. The attacker gains the ability to write arbitrary files with SYSTEM privileges or overwrite critical system files

This local attack vector means the vulnerability is most dangerous in scenarios where untrusted users have interactive access to systems running the vulnerable McAfee Agent, such as shared workstations or terminal servers.

Detection Methods for CVE-2022-1256

Indicators of Compromise

• Unusual symbolic links appearing in user %TEMP% directories pointing to system paths such as C:\Windows\System32
• McAfee Agent repair processes being triggered unexpectedly or by non-administrative users
• File creation or modification events in privileged directories originating from McAfee Agent processes but triggered by low-privilege users

Detection Strategies

• Monitor for symbolic link creation in user temporary directories (%USERPROFILE%\AppData\Local\Temp) using file system auditing
• Implement detection rules for McAfee Agent repair functionality being invoked outside of normal maintenance windows
• Use endpoint detection tools to alert on junction point or symbolic link creation followed by privilege escalation indicators
• Audit McAfee Agent version across all endpoints to identify systems running versions prior to 5.7.6

Monitoring Recommendations

• Enable Windows Security Event logging for file system operations, particularly Event ID 4663 (attempt to access an object)
• Configure SIEM rules to correlate McAfee Agent process activity with unexpected file operations in system directories
• Implement baseline monitoring for symbolic link creation patterns in enterprise environments to detect anomalous behavior

How to Mitigate CVE-2022-1256

Immediate Actions Required

• Upgrade McAfee Agent for Windows to version 5.7.6 or later immediately on all affected systems
• Audit systems to identify any endpoints running vulnerable versions using McAfee ePolicy Orchestrator or asset inventory tools
• Restrict repair functionality access where possible until patching is complete
• Monitor user temporary directories for suspicious symbolic link activity as an interim detection measure

Patch Information

McAfee has released a security update addressing this vulnerability. The fix is included in McAfee Agent for Windows version 5.7.6 and later. Organizations should consult the McAfee Security Advisory SB10382 for detailed patching instructions and deployment guidance.

For enterprises using McAfee ePolicy Orchestrator (ePO), the updated agent can be deployed centrally. Ensure that all managed endpoints receive the update and verify successful installation through compliance reporting.

Workarounds

• Limit interactive logon access on systems running the vulnerable McAfee Agent to reduce the attack surface
• Implement application whitelisting to prevent unauthorized processes from creating symbolic links in temporary directories
• Use Windows Group Policy to restrict symbolic link creation capabilities where operationally feasible
• Consider temporary removal of repair functionality access for non-administrative users until patching is complete