CVE-2005-0988 in gzip
Summary
by MITRE
race condition in gzip 1.2.4 1.3.3 and earlier when decompressing a gzipped file allows local users to modify permissions of arbitrary files via a hard link attack on a file while it is being decompressed whose permissions are changed by gzip after the decompression is complete.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/01/2019
The vulnerability described in CVE-2005-0988 represents a critical race condition affecting gzip versions 1.2.4 through 1.3.3, where local attackers can exploit a timing weakness during file decompression to manipulate file permissions. This issue stems from the fundamental design flaw in how gzip handles file operations during decompression processes, creating an exploitable window between when a file is initially processed and when its permissions are subsequently modified.
The technical flaw occurs when gzip decompresses a gzipped file that contains a hard link to another file in the system. During the decompression process, gzip creates a temporary file or modifies the target file while the decompression is underway, but the permission changes are deferred until after the decompression completes. This creates a temporal gap where an attacker can manipulate the file system state by replacing the original file with a hard link to another target file, allowing the permission modification to be applied to the unintended file instead of the intended one.
The operational impact of this vulnerability extends beyond simple permission manipulation, as it enables attackers to potentially escalate privileges or gain unauthorized access to sensitive system resources. The race condition typically occurs in scenarios where gzip is used in automated processes or system scripts that handle user input, making it particularly dangerous in environments where decompression operations are performed with elevated privileges. Attackers can leverage this weakness to modify permissions of critical system files, configuration files, or even files belonging to other users, potentially compromising system integrity and confidentiality.
This vulnerability aligns with CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and demonstrates how improper handling of file system operations can lead to serious security implications. From an ATT&CK perspective, this weakness maps to privilege escalation techniques and can be classified under T1068, which involves exploiting vulnerabilities to gain elevated privileges. The attack vector specifically relates to T1059, where attackers manipulate system processes to achieve their objectives, and T1548, which involves establishing persistence through privilege escalation mechanisms.
The mitigation strategy for this vulnerability requires immediate patching of affected gzip versions to the latest stable releases that address the race condition. System administrators should also implement proper file system permissions and access controls to limit the impact of potential exploitation. Additionally, processes that invoke gzip should be reviewed to ensure they are not running with unnecessary elevated privileges, and decompression operations should be performed in secure temporary directories with restricted permissions. Organizations should consider implementing file integrity monitoring solutions to detect unauthorized permission changes and establish regular security audits to identify and remediate similar vulnerabilities in other system components.