CVE-2015-7724 in fglrx-driver
Summary
by MITRE
AMD fglrx-driver before 15.9 allows local users to gain privileges via a symlink attack. NOTE: This vulnerability exists due to an incomplete fix for CVE-2015-7723.
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Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2015-7724 represents a privilege escalation flaw within the AMD fglrx graphics driver version 15.9 and earlier. This issue specifically affects systems running Linux distributions with AMD graphics hardware and demonstrates how incomplete security fixes can leave persistent attack surfaces. The vulnerability stems from a symlink attack that allows local users to escalate their privileges, making it particularly concerning for environments where untrusted users might have access to system resources.
The technical root cause of this vulnerability lies in the improper handling of symbolic links within the AMD fglrx driver components. When the driver processes certain file operations, it fails to properly validate or sanitize symbolic link references, creating opportunities for attackers to manipulate file paths and gain elevated privileges. This flaw operates at the kernel level where driver components interact with system resources, making it particularly dangerous as it can be exploited without requiring network access or remote execution capabilities. The vulnerability specifically affects the driver's privilege management mechanisms, allowing attackers to bypass normal access controls and execute code with higher privileges than initially granted.
The operational impact of CVE-2015-7724 extends beyond simple privilege escalation, as it represents a critical weakness in system security that can be exploited by local attackers with minimal privileges. Attackers can leverage this vulnerability to gain root access to affected systems, potentially leading to complete system compromise, data exfiltration, or persistent backdoor installation. The attack vector is particularly concerning because it requires only local access, meaning that even in environments with network segmentation, an attacker who gains access to a user account can potentially escalate privileges without requiring additional attack vectors. This makes the vulnerability especially dangerous in multi-user environments, shared computing systems, or scenarios where users might have legitimate access to system resources.
This vulnerability is categorized under CWE-59, which relates to improper handling of symbolic links, and aligns with ATT&CK techniques involving privilege escalation and persistence mechanisms. The incomplete fix for CVE-2015-7723 that led to this vulnerability demonstrates how security patches can sometimes introduce new issues or fail to address all attack surfaces. Organizations should prioritize immediate patching of affected systems to address this vulnerability, ensuring that the AMD fglrx driver is updated to version 15.9 or later. System administrators should also implement monitoring for suspicious symlink operations and consider implementing additional security controls such as mandatory access controls or file integrity monitoring to detect potential exploitation attempts. The vulnerability underscores the importance of comprehensive security testing and validation of security patches, particularly for kernel-level components that handle privileged operations.
The presence of this vulnerability in the fglrx driver ecosystem highlights the broader challenge of maintaining secure graphics driver implementations. Graphics drivers operate with elevated privileges and have complex interactions with system resources, making them attractive targets for exploitation. Organizations should consider alternative graphics driver solutions or implement additional security measures such as kernel lockdown features, secure boot configurations, and regular security assessments of driver components to prevent similar vulnerabilities from being exploited in the future.