CVE-2012-4578 in FreeBSD
Summary
by MITRE
The geli encryption provider 7 before r239184 on FreeBSD 10 uses a weak Master Key, which makes it easier for local users to defeat a cryptographic protection mechanism via a brute-force attack.
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Analysis
by VulDB Data Team • 04/01/2019
The CVE-2012-4578 vulnerability affects the geli encryption provider in FreeBSD versions prior to r239184, specifically impacting FreeBSD 10 systems. This weakness resides in the cryptographic implementation of the geli subsystem which is responsible for disk encryption and decryption operations. The vulnerability stems from the use of a weak master key generation mechanism that significantly reduces the entropy and complexity of the encryption keys used by the system. This flaw represents a critical security issue as it directly undermines the cryptographic protection that geli is designed to provide for disk encryption.
The technical flaw manifests in the insufficient randomness and predictability of the master key generation process within the geli encryption provider. When cryptographic systems generate keys, they must utilize high-entropy sources to ensure that the resulting keys are computationally infeasible to guess or brute-force through traditional attack methods. However, in this case, the geli implementation fails to properly randomize the master key derivation process, creating patterns or reduced key spaces that make the encryption vulnerable to systematic attack approaches. The weak key generation mechanism essentially provides attackers with a reduced search space for potential key combinations, making brute-force attacks significantly more practical and efficient than they should be under proper cryptographic standards.
The operational impact of this vulnerability extends beyond simple encryption weakness, as it creates opportunities for local users to compromise encrypted data without requiring sophisticated attack vectors or extensive computational resources. Attackers can exploit this weakness to perform brute-force attacks against the geli-encrypted volumes, potentially gaining unauthorized access to sensitive data stored on the system. This vulnerability particularly affects systems where geli is used for full disk encryption or encryption of sensitive data partitions, as the compromised encryption mechanism directly threatens the confidentiality and integrity of the protected information. The local user access requirement means that an attacker must already have access to the system, but once inside, they can leverage this weakness to bypass the intended cryptographic protections.
Mitigation strategies for CVE-2012-4578 primarily focus on upgrading to FreeBSD versions that include the patched geli implementation, specifically those with revision r239184 or later. System administrators should prioritize updating their FreeBSD installations to ensure that the master key generation process uses proper cryptographic randomness and entropy sources. Additionally, organizations should consider implementing additional security controls such as monitoring for unauthorized access attempts and regular security audits of encryption implementations. The vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms and key generation processes, and represents a significant concern from an attacker's perspective as outlined in the ATT&CK framework under credential access and defense evasion techniques. Proper key management practices and regular system updates remain essential defenses against similar vulnerabilities in cryptographic implementations.