CVE-2012-0955 in Software-properties
Summary
by MITRE • 12/02/2020
software-properties was vulnerable to a person-in-the-middle attack due to incorrect TLS certificate validation in softwareproperties/ppa.py. software-properties didn't check TLS certificates under python2 and only checked certificates under python3 if a valid certificate bundle was provided. Fixed in software-properties version 0.92.
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Analysis
by VulDB Data Team • 12/11/2020
The vulnerability identified as CVE-2012-0955 affects the software-properties package, a critical component in Ubuntu and Debian-based systems responsible for managing software repositories and package sources. This flaw represents a significant security weakness that undermines the integrity of package installation processes by failing to properly validate TLS certificates during secure communications. The vulnerability specifically resides in the softwareproperties/ppa.py module where the implementation of secure communication protocols does not adequately verify server authenticity, creating an opening for malicious actors to intercept and manipulate package distribution channels.
The technical implementation of this vulnerability stems from inadequate certificate validation mechanisms within the software-properties framework. Under python2 environments, the system completely bypassed TLS certificate verification entirely, while in python3 environments, certificate validation only occurred when a valid certificate bundle was explicitly provided. This dual failure mode means that regardless of the Python version in use, the system remained vulnerable to man-in-the-middle attacks where attackers could present fraudulent certificates to deceive the package management system into accepting malicious software packages. The flaw directly relates to CWE-295 which addresses improper certificate validation and represents a critical weakness in the security architecture of package management systems.
The operational impact of this vulnerability extends far beyond simple network communication issues, as it fundamentally compromises the security of software distribution within affected systems. When users attempt to install packages from repositories, the system becomes susceptible to attacks where malicious actors can intercept package downloads and replace legitimate software with compromised versions. This vulnerability enables attackers to potentially inject backdoors, malware, or other malicious code into systems, as the package management system no longer validates the authenticity of the software sources. The attack vector aligns with ATT&CK technique T1059 which involves executing malicious code through compromised software supply chains, making this vulnerability particularly dangerous in enterprise and organizational environments.
The mitigation for this vulnerability required a comprehensive fix in the software-properties package version 0.92, which implemented proper TLS certificate validation across both python2 and python3 environments. This fix ensures that all secure communications between package management systems and repository servers undergo proper certificate verification, preventing the acceptance of fraudulent certificates. Organizations should immediately update their software-properties packages to version 0.92 or later to remediate this vulnerability, as the risk of exploitation remains high given the widespread use of affected systems. The fix demonstrates the importance of maintaining proper certificate validation practices in security-critical components and underscores the need for robust secure communication protocols in package management systems.