CVE-2007-4131 in tar
Summary
by MITRE
Directory traversal vulnerability in the contains_dot_dot function in src/names.c in GNU tar allows user-assisted remote attackers to overwrite arbitrary files via certain //.. (slash slash dot dot) sequences in directory symlinks in a TAR archive.
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Analysis
by VulDB Data Team • 07/25/2019
The vulnerability identified as CVE-2007-4131 represents a critical directory traversal flaw within the GNU tar archival utility that has significant implications for system security and data integrity. This vulnerability specifically affects the contains_dot_dot function located in the src/names.c source file of the GNU tar implementation, creating a pathway for malicious actors to exploit the software's handling of symbolic links within TAR archives. The flaw manifests when tar processes directory symlinks containing specific //.. sequences that should normally be rejected or properly sanitized during archive extraction. The vulnerability is classified as user-assisted remote, meaning that an attacker must convince a victim to extract a maliciously crafted TAR archive, but once triggered, the attack can potentially result in arbitrary file overwrite operations.
The technical mechanism behind this vulnerability stems from improper validation of directory traversal sequences within symbolic link paths during tar archive processing. When GNU tar encounters a symlink that contains the //.. pattern, the contains_dot_dot function fails to properly recognize and reject these potentially dangerous sequences that could lead to directory traversal attacks. This weakness allows attackers to construct TAR archives with symbolic links that, when extracted, can overwrite files outside of the intended extraction directory. The vulnerability operates at the file system level where the tar utility's path resolution logic does not adequately sanitize input sequences, creating an opportunity for privilege escalation or data corruption attacks. According to CWE classification, this represents a directory traversal vulnerability (CWE-22) that specifically involves improper handling of path traversal sequences in archive processing.
The operational impact of CVE-2007-4131 extends beyond simple file overwrite capabilities and can enable more sophisticated attack vectors within system environments. An attacker exploiting this vulnerability can potentially overwrite critical system files, configuration files, or even executables, leading to service disruption, privilege escalation, or complete system compromise. The vulnerability is particularly dangerous in environments where tar is used for automated file extraction processes or where users have the ability to process untrusted archives. When combined with other attack techniques, this vulnerability can facilitate broader security breaches within networked systems. The attack surface includes web applications that process user-uploaded archives, automated backup systems, and any environment where tar archives are processed without proper validation of symbolic link contents. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and persistence through file system manipulation.
Mitigation strategies for CVE-2007-4131 should focus on both immediate patching and operational security measures. The most effective solution involves updating to GNU tar versions that contain the fix for the directory traversal vulnerability in the contains_dot_dot function, which typically includes proper validation of path sequences and rejection of dangerous //.. patterns. System administrators should implement strict archive validation procedures that inspect archive contents before extraction, particularly focusing on symbolic link paths that contain traversal sequences. Network security controls should be enhanced to prevent untrusted archives from being processed automatically, and users should be educated about the risks of extracting archives from untrusted sources. Additional protective measures include implementing proper file system permissions, using restricted extraction environments, and deploying automated scanning systems that can detect and quarantine suspicious archive contents. Organizations should also consider implementing sandboxing techniques for archive processing and establishing robust incident response procedures to address potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation in archive processing utilities and highlights the need for comprehensive security testing of file manipulation software in enterprise environments.