CVE-2007-6150 in FreeBSD
Summary
by MITRE
The "internal state tracking" code for the random and urandom devices in FreeBSD 5.5, 6.1 through 6.3, and 7.0 beta 4 allows local users to obtain portions of previously-accessed random values, which could be leveraged to bypass protection mechanisms that rely on secrecy of those values.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/12/2018
The vulnerability described in CVE-2007-6150 represents a critical flaw in FreeBSD's implementation of cryptographic random number generation mechanisms. This issue affects FreeBSD versions 5.5, 6.1 through 6.3, and 7.0 beta 4, where the internal state tracking code for both the random and urandom devices contains a design flaw that compromises the security of generated random values. The vulnerability stems from insufficient entropy mixing and state management within the kernel's random number generation subsystem, creating a scenario where previously generated values can be partially reconstructed by local attackers.
The technical flaw manifests through improper state management in the random number generator's internal buffers and tracking mechanisms. When the system generates random values, it maintains an internal state that should be thoroughly mixed and updated after each generation operation. However, the implementation fails to properly clear or sufficiently randomize the internal state between successive calls, allowing portions of previously accessed random values to persist in memory or buffer areas. This creates a situation where an attacker with local access can potentially reconstruct parts of the random sequence, effectively reducing the entropy and predictability of the generated values. The vulnerability is classified under CWE-330 as "Use of Insufficiently Random Values" and represents a fundamental failure in cryptographic implementation that violates the core principles of randomness required for security applications.
The operational impact of this vulnerability is significant for systems relying on FreeBSD's random number generation for cryptographic operations. Local users can exploit this flaw to compromise the security of applications that depend on the random number generator for key generation, session token creation, or other security-critical functions. The vulnerability enables attackers to potentially predict future random values or reconstruct past values, which could lead to session hijacking, cryptographic key compromise, or bypass of authentication mechanisms that rely on random values for security. This weakness directly impacts the confidentiality and integrity of security protocols that depend on cryptographically secure random number generation, making it particularly dangerous in environments where multiple applications share the same random number source.
Mitigation strategies for this vulnerability require immediate system updates to patched FreeBSD versions that address the internal state tracking implementation. System administrators should prioritize upgrading affected systems to versions that contain proper entropy mixing and state clearing mechanisms in the random number generator. Additionally, applications should implement additional entropy sources or cryptographic libraries that do not rely solely on the system's random number generator for critical security operations. The ATT&CK framework categorizes this vulnerability under T1083 as "File and Directory Discovery" and T1552 as "Unsecured Credentials" since it enables attackers to access previously generated random values that might be used for credential generation or session management. Organizations should also consider implementing monitoring solutions to detect unusual patterns in random number generation or potential exploitation attempts that might indicate this vulnerability is being actively targeted.