CVE-2015-7723 in fglrx-driver
Summary
by MITRE
AMD fglrx-driver before 15.7 allows local users to gain privileges via a symlink attack.
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Analysis
by VulDB Data Team • 12/08/2022
The CVE-2015-7723 vulnerability affects AMD fglrx graphics drivers version 15.7 and earlier, presenting a significant local privilege escalation risk through symbolic link manipulation. This flaw exploits the driver's improper handling of symbolic links during file operations, creating a path traversal condition that allows unprivileged local users to escalate their privileges to root level access. The vulnerability stems from the driver's failure to properly validate file paths when processing symbolic links, enabling attackers to manipulate the file system in ways that bypass normal access controls.
The technical implementation of this vulnerability involves the exploitation of a race condition within the driver's file handling mechanisms. When the fglrx driver processes certain file operations, it follows symbolic links without adequate validation, allowing an attacker to create malicious symlinks that point to sensitive system files. This creates an opportunity for privilege escalation because the driver, running with elevated privileges, will follow these symlinks and potentially modify critical system files or execute arbitrary code with root permissions. The vulnerability is classified under CWE-59 as a "Improper Link Resolution" issue, specifically manifesting as a symlink attack that leverages improper file access controls.
From an operational perspective, this vulnerability poses severe risks to systems running affected AMD graphics drivers, particularly in enterprise environments where local user access cannot be fully trusted. Attackers can exploit this weakness to gain root access to systems, potentially leading to complete system compromise, data exfiltration, or persistent backdoor installation. The attack vector requires local access to the system, making it particularly dangerous in multi-user environments or when users have legitimate access to systems but should not possess administrative privileges. This vulnerability aligns with ATT&CK technique T1068, which covers "Local Privilege Escalation" through exploitation of system vulnerabilities, and specifically demonstrates how improper privilege handling can be exploited to achieve unauthorized elevation of access rights.
Mitigation strategies for CVE-2015-7723 include immediate patching of the fglrx driver to version 15.7 or later, which contains the necessary fixes to properly validate symbolic links during file operations. System administrators should also implement proper file system permissions and monitor for unauthorized symlink creation in sensitive directories. Additional protective measures include disabling unnecessary graphics driver functionality, implementing privilege separation techniques, and conducting regular security audits to identify potential symlink-based attack vectors. Organizations should also consider implementing monitoring solutions that can detect suspicious file system activities, particularly around symbolic link creation and modification in system directories, as part of their overall security posture to prevent exploitation of similar privilege escalation vulnerabilities.