CVE-2004-1901 in Portage
Summary
by MITRE
Portage before 2.0.50-r3 allows local users to overwrite arbitrary files via a hard link attack on the lockfiles.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 01/16/2025
The vulnerability identified as CVE-2004-1901 affects Portage, the package management system used by Gentoo Linux distributions. This flaw represents a significant security weakness that could be exploited by local attackers to manipulate file system contents through a carefully crafted hard link attack against lockfiles. The vulnerability specifically exists in Portage versions prior to 2.0.50-r3, making older Gentoo installations particularly susceptible to this type of attack vector. The core issue stems from inadequate file handling procedures during package installation and management operations.
The technical flaw manifests when Portage creates lockfiles to ensure exclusive access during package operations. Local users can exploit this by creating symbolic links or hard links to the target lockfile location before the legitimate process attempts to create it. When Portage subsequently attempts to write to what it believes is a lockfile, it actually overwrites the target file that the malicious user has linked to, potentially allowing arbitrary file modification. This attack pattern aligns with CWE-59, which describes improper handling of hard links, and represents a classic example of a race condition vulnerability where timing between file creation and access determines the security outcome.
The operational impact of this vulnerability extends beyond simple file overwriting, as it could potentially allow attackers to modify critical system files, configuration data, or even executable programs. An attacker with local access could leverage this weakness to escalate privileges, corrupt system integrity, or establish persistent access points within the affected system. The attack requires only local user privileges and knowledge of the specific file system paths involved, making it particularly dangerous in multi-user environments where users may have varying levels of access. This vulnerability directly relates to ATT&CK technique T1068, which covers local privilege escalation through race conditions and file system manipulation.
Mitigation strategies for CVE-2004-1901 primarily involve upgrading to Portage version 2.0.50-r3 or later, which includes proper lockfile handling mechanisms that prevent the hard link attack vector. System administrators should also implement proper file system permissions and monitoring to detect unauthorized file modifications. Additional protective measures include regular security audits of package management operations, implementation of file integrity monitoring solutions, and ensuring that only trusted users have local access to systems running Portage. The vulnerability demonstrates the importance of proper file system security practices and highlights how seemingly minor implementation flaws in package management systems can have significant security implications across entire operating environments.