CVE-2002-1107 in VPN Client
Summary
by MITRE
Cisco Virtual Private Network (VPN) Client software 2.x.x, and 3.x before 3.5.2B, does not generate sufficiently random numbers, which may make it vulnerable to certain attacks such as spoofing.
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Analysis
by VulDB Data Team • 04/19/2019
The vulnerability identified as CVE-2002-1107 affects Cisco Virtual Private Network VPN Client software versions 2.x.x and 3.x prior to 3.5.2B, representing a critical weakness in the cryptographic random number generation mechanisms employed by the software. This flaw stems from insufficient entropy in the random number generation process, which forms the foundation of many security protocols including those used for authentication and key exchange within VPN connections. The vulnerability falls under the broader category of weak cryptographic randomness as classified by CWE-330, which specifically addresses the use of insufficiently random values in cryptographic operations.
The technical implementation of this vulnerability lies in the client-side software's inability to produce cryptographically secure random numbers that are essential for establishing secure communication channels. When VPN clients generate random numbers for session keys, nonces, or other cryptographic parameters, the predictability of these values creates opportunities for attackers to compromise the security of the VPN connections. This weakness directly impacts the integrity and confidentiality of data transmitted through the VPN, as adversaries could potentially predict or reproduce the random values used in cryptographic operations. The vulnerability aligns with ATT&CK technique T1552.004, which involves the exploitation of weak or predictable random number generation to compromise cryptographic systems.
The operational impact of this vulnerability extends beyond simple authentication bypasses to encompass broader security compromise scenarios where attackers can perform man-in-the-middle attacks, session hijacking, or impersonation of legitimate users within the VPN environment. The predictability of random numbers undermines the fundamental security assumptions of the VPN protocol stack, making it possible for malicious actors to forge authentication tokens or decrypt network traffic. This weakness particularly affects organizations relying on Cisco VPN clients for remote access, as it creates persistent security gaps that can be exploited over time. The vulnerability also demonstrates the importance of proper random number generation in security protocols, as highlighted in industry standards such as NIST SP 800-90A, which emphasizes the requirements for cryptographically secure pseudorandom number generators.
Organizations should immediately implement mitigations including updating to Cisco VPN Client software versions 3.5.2B or later, which contain corrected random number generation algorithms. Additionally, network administrators should consider implementing additional security controls such as multi-factor authentication, network segmentation, and continuous monitoring of VPN access patterns to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper entropy sources in cryptographic implementations and the need for regular security assessments of network infrastructure components. System administrators should also review their overall security posture and consider alternative VPN solutions that demonstrate stronger cryptographic implementations, particularly for environments handling sensitive data or mission-critical communications.