CVE-2012-5356 in Ubuntu Software Properties
Summary
by MITRE
The apt-add-repository tool in Ubuntu Software Properties 0.75.x before 0.75.10.3, 0.80.x before 0.80.9.2, 0.81.x before 0.81.13.5, 0.82.x before 0.82.7.3, and 0.92.x before 0.92.8 does not properly check PPA GPG keys imported from a keyserver, which allows remote attackers to install arbitrary package repository GPG keys via a man-in-the-middle (MITM) attack.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2012-5356 represents a critical security flaw in the apt-add-repository utility within Ubuntu Software Properties, affecting multiple version streams from 0.75.x through 0.92.x. This issue stems from insufficient validation mechanisms when importing GPG keys from remote key servers, creating a significant attack surface that adversaries can exploit to compromise system integrity. The vulnerability specifically targets the trust verification process that should occur when adding new package repositories to the system, allowing malicious actors to bypass normal security controls through carefully crafted man-in-the-middle attacks.
The technical implementation of this vulnerability resides in the improper handling of GPG key verification within the apt-add-repository tool's key import functionality. When users attempt to add a PPA repository using this utility, the system retrieves the corresponding GPG key from a keyserver to verify package authenticity. However, the flawed implementation fails to properly validate the key's authenticity and origin, allowing attackers who control the network path between the system and the keyserver to substitute legitimate keys with malicious ones. This weakness directly maps to CWE-295, which addresses improper certificate validation, and falls under the broader category of trust management failures in cryptographic systems. The vulnerability enables attackers to execute arbitrary code through package installation, as the system will trust packages signed with the compromised key as if they came from legitimate sources.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security model of package management in Ubuntu systems. Attackers can leverage this weakness to install malicious packages that appear legitimate to the system, potentially leading to complete system compromise through supply chain attacks. The vulnerability affects a wide range of Ubuntu versions, making it particularly dangerous as it could impact numerous systems across different release cycles. This flaw particularly threatens environments where automated package management occurs, as the compromised trust model could persist across multiple system updates and installations, creating long-term security exposure. The attack vector requires only network-level access to intercept and modify key exchanges, making it relatively easy to exploit in practice.
Mitigation strategies for CVE-2012-5356 must address both immediate remediation and long-term security posture improvements. The most direct solution involves updating to patched versions of Ubuntu Software Properties, specifically versions 0.75.10.3, 0.80.9.2, 0.81.13.5, 0.82.7.3, and 0.92.8 or later. Organizations should also implement additional verification measures such as manually verifying GPG key fingerprints before adding repositories, utilizing secure keyserver connections through HTTPS or other encrypted protocols, and establishing network monitoring to detect unauthorized key modifications. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving trusted relationship exploitation and credential access through supply chain compromise. System administrators should also consider implementing network segmentation and traffic inspection to prevent unauthorized keyserver communication, while maintaining comprehensive audit logs of all repository additions and key imports to detect potential exploitation attempts.