CVE-2012-3587 in APT
Summary
by MITRE
APT 0.7.x before 0.7.25 and 0.8.x before 0.8.16, when using the apt-key net-update to import keyrings, relies on GnuPG argument order and does not check GPG subkeys, which might allow remote attackers to install Trojan horse packages via a man-in-the-middle (MITM) attack.
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Analysis
by VulDB Data Team • 12/04/2021
The vulnerability described in CVE-2012-3587 represents a critical weakness in the Advanced Package Tool (APT) ecosystem that emerged from improper handling of GnuPG key validation during package repository management operations. This flaw specifically affects APT versions 0.7.x prior to 0.7.25 and 0.8.x prior to 0.8.16, creating a window of opportunity for malicious actors to compromise system integrity through sophisticated man-in-the-middle attacks. The vulnerability stems from the tool's reliance on GnuPG argument order rather than implementing proper cryptographic verification mechanisms, fundamentally undermining the security assurances that package signing should provide.
The technical implementation of this vulnerability exploits a critical design flaw in how APT processes GPG key imports when executing the apt-key net-update command. Rather than properly validating that imported keys are legitimate and have not been tampered with during transmission, the system depends on the order of arguments passed to GnuPG, which creates predictable patterns that attackers can manipulate. Additionally, the system fails to check GPG subkeys, meaning that even if a primary key appears valid, compromised subkeys could be used to bypass security controls entirely. This oversight creates a scenario where an attacker positioned between a client and a package repository can intercept and modify package signatures, effectively allowing them to install malicious software that appears to be legitimate updates.
The operational impact of this vulnerability extends far beyond simple package management disruption, creating a comprehensive attack vector that can lead to full system compromise and persistent backdoor access. When attackers successfully exploit this vulnerability, they can inject malicious packages into trusted repositories, which then get installed automatically on systems that trust those repositories. This creates a particularly dangerous scenario because the compromised packages can contain trojan horses that execute arbitrary code, establish persistence mechanisms, or provide remote access capabilities to attackers. The vulnerability effectively undermines the entire package management security model by allowing attackers to subvert the trust relationship between package repositories and client systems.
This vulnerability aligns with CWE-225, which addresses weaknesses in the improper handling of arguments in cryptographic operations, and relates to ATT&CK technique T1195.002 for 'Supply Chain Compromise' through the manipulation of package repositories. The flaw also connects to ATT&CK technique T1059.001 for 'Command and Scripting Interpreter' as attackers can execute malicious code through compromised package installations. Organizations affected by this vulnerability should immediately update to APT versions 0.7.25 or 0.8.16, which contain proper GPG validation checks and subkey verification mechanisms. Additionally, system administrators should implement network monitoring to detect unusual package installation patterns and consider implementing additional repository validation measures such as manual key verification processes and certificate pinning for critical systems. The vulnerability underscores the importance of proper cryptographic implementation and the necessity of comprehensive security testing for critical system components that handle trust relationships and package integrity verification.