CVE-2016-8492 in FortiWLC
Summary
by MITRE
The implementation of an ANSI X9.31 RNG in Fortinet FortiWLC allows attackers to gain unauthorized read access to data handled by the device via IPSec/TLS decryption.
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Analysis
by VulDB Data Team • 09/01/2020
The vulnerability identified as CVE-2016-8492 resides within the ANSI X9.31 random number generator implementation found in Fortinet FortiWLC wireless LAN controllers. This cryptographic weakness represents a significant security flaw that directly impacts the device's ability to maintain secure communications through IPSec and TLS decryption processes. The vulnerability stems from improper implementation of the random number generation algorithm that is critical for generating cryptographic keys and nonces used in secure communication protocols.
The technical flaw manifests in the deterministic nature of the random number generator which fails to meet the cryptographic requirements for secure key generation. According to CWE-330, this represents a weakness in the use of cryptographically weak random number generators where the implementation does not provide sufficient entropy or unpredictability. The ANSI X9.31 standard requires robust random number generation for cryptographic operations, but the Fortinet implementation falls short of these requirements, creating predictable sequences that can be exploited by attackers. This weakness directly violates the principles outlined in NIST SP 800-90A regarding the requirements for random number generation in cryptographic applications.
The operational impact of this vulnerability extends beyond simple data access issues to encompass complete compromise of secure communications within the network. Attackers who can exploit this weakness gain the ability to perform man-in-the-middle attacks against IPSec and TLS connections, potentially decrypting sensitive traffic and accessing confidential data. The vulnerability affects the core security functions of the FortiWLC device, which serves as a central point for wireless network management and security enforcement. This creates a critical attack surface that can be leveraged to escalate privileges, access network resources, and potentially pivot to other systems within the network infrastructure.
The attack vector for this vulnerability typically involves an attacker who gains access to the wireless network controller or can perform network reconnaissance to understand the cryptographic implementation. Once the predictable random number sequences are identified, attackers can potentially reconstruct cryptographic keys used for IPSec and TLS encryption, enabling them to decrypt communications between wireless clients and network resources. This aligns with ATT&CK technique T1041 which describes data compression and encryption methods that can be exploited to bypass network security controls. The vulnerability also maps to ATT&CK technique T1566 which covers social engineering attacks that could potentially be used to gain initial access to the wireless infrastructure.
Mitigation strategies for CVE-2016-8492 require immediate attention through firmware updates provided by Fortinet to address the flawed random number generator implementation. Organizations should also implement network segmentation to limit the attack surface and monitor for unusual network traffic patterns that might indicate exploitation attempts. Additional security measures include implementing alternative cryptographic protocols that do not rely on the vulnerable RNG implementation, conducting regular security assessments of wireless infrastructure, and maintaining up-to-date threat intelligence to detect potential exploitation attempts. The vulnerability highlights the critical importance of proper cryptographic implementation and the necessity of regular security audits to identify and remediate weaknesses in cryptographic libraries used within network infrastructure devices.