CVE-2008-3524 in Fedora
Summary
by MITRE
rc.sysinit in initscripts before 8.76.3-1 on Fedora 9 and other Linux platforms allows local users to delete arbitrary files via a symlink attack on a file or directory under (1) /var/lock or (2) /var/run.
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Analysis
by VulDB Data Team • 08/17/2019
The vulnerability described in CVE-2008-3524 represents a critical race condition and privilege escalation issue within the rc.sysinit script of the initscripts package on Fedora 9 and similar Linux distributions. This flaw exists in the initialization process where the system performs cleanup operations on lock and run directories during boot sequences. The vulnerability stems from improper handling of symbolic links during file operations, creating a window where malicious users can manipulate the filesystem to gain unauthorized access to system resources. The affected directories /var/lock and /var/run serve as critical system locations where process identifiers and lock files are stored, making this vulnerability particularly dangerous for system integrity and security.
The technical implementation of this vulnerability involves a classic symlink attack pattern where an attacker creates malicious symbolic links in the target directories before the rc.sysinit script processes them. During the boot process, the script performs operations such as removing stale lock files or cleaning up process identifier files in these directories. When the script encounters a symbolic link, it follows the link and performs operations on the target file rather than the intended symbolic link itself. This behavior allows attackers to redirect file operations to arbitrary locations on the filesystem, potentially enabling them to delete or overwrite critical system files, modify permissions, or even escalate privileges to root access. The vulnerability is classified under CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions.
The operational impact of this vulnerability extends beyond simple file deletion capabilities, as it provides a foothold for more sophisticated attacks within the system. An attacker with local access can exploit this weakness to compromise system integrity by removing critical lock files that prevent concurrent access to shared resources, potentially causing system instability or denial of service conditions. The vulnerability also enables privilege escalation scenarios where attackers can manipulate system files in /var/run to gain elevated permissions, particularly when combined with other local privilege escalation techniques. According to ATT&CK framework, this vulnerability maps to T1068 (Local Privilege Escalation) and T1490 (Inhibit System Recovery), as it can be used to disrupt system recovery mechanisms and gain unauthorized access to system resources.
Mitigation strategies for CVE-2008-3524 require immediate patching of the initscripts package to version 8.76.3-1 or later, which addresses the race condition by implementing proper file existence checks and avoiding symbolic link traversal during critical operations. System administrators should also implement proper file system permissions and access controls on the affected directories, ensuring that only authorized processes can write to /var/lock and /var/run. Additional protective measures include monitoring for unauthorized symbolic link creation in these directories, implementing mandatory access controls through SELinux or AppArmor, and conducting regular security audits of system initialization scripts. The vulnerability highlights the importance of secure coding practices in system-level scripts and the need for proper input validation and race condition prevention mechanisms. Organizations should also consider implementing file integrity monitoring solutions to detect unauthorized modifications to critical system files and directories that could indicate exploitation attempts.