CVE-2018-15769 in RSA BSAFE Micro Edition Suite
Summary
by MITRE
RSA BSAFE Micro Edition Suite versions prior to 4.0.11 (in 4.0.x series) and versions prior to 4.1.6.2 (in 4.1.x series) contain a key management error issue. A malicious TLS server could potentially cause a Denial Of Service (DoS) on TLS clients during the handshake when a very large prime value is sent to the TLS client, and an Ephemeral or Anonymous Diffie-Hellman cipher suite (DHE or ADH) is used.
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Analysis
by VulDB Data Team • 06/06/2023
The vulnerability identified as CVE-2018-15769 represents a critical weakness in RSA BSAFE Micro Edition Suite implementations that affects multiple version series including 4.0.x prior to 4.0.11 and 4.1.x prior to 4.1.6.2. This issue stems from improper handling of cryptographic key management during TLS protocol negotiations, specifically when clients encounter unexpectedly large prime values during Diffie-Hellman key exchange operations. The flaw manifests during the TLS handshake process when clients attempt to validate Diffie-Hellman parameters, creating a potential attack surface that adversaries can exploit to disrupt normal communication channels.
The technical root cause of this vulnerability lies in the insufficient validation and resource management of prime number parameters within the Diffie-Hellman key exchange mechanism. When a malicious TLS server presents an abnormally large prime value to a vulnerable client, the client's cryptographic library fails to properly handle this oversized parameter, leading to excessive memory consumption or computational overhead. This behavior aligns with CWE-122, which describes heap-based buffer overflow conditions, and CWE-131, which addresses incorrect calculation of buffer or object sizes. The vulnerability specifically impacts systems using Ephemeral (DHE) or Anonymous (ADH) Diffie-Hellman cipher suites, where the security model relies heavily on proper parameter validation and resource allocation during key exchange operations.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader security implications for affected systems. A successful exploitation can result in complete denial of service conditions where legitimate clients become unable to establish secure TLS connections with servers, effectively rendering the communication channel unusable. This DoS condition affects not only individual client-server interactions but can potentially cascade through network infrastructure, particularly in environments where multiple clients rely on the same vulnerable cryptographic library. The attack requires minimal privileges and can be executed remotely, making it particularly dangerous in production environments where availability is critical. Organizations utilizing embedded systems, IoT devices, or any platform running the affected BSAFE versions face significant risk of service disruption and potential business impact.
Mitigation strategies for CVE-2018-15769 primarily focus on immediate version upgrades to patched releases of RSA BSAFE Micro Edition Suite, specifically targeting versions 4.0.11 and 4.1.6.2 or later. System administrators should conduct comprehensive inventory assessments to identify all affected devices and applications using the vulnerable library, particularly in embedded environments where patching may be complex. Network administrators can implement temporary workarounds such as disabling DHE and ADH cipher suites in TLS configurations, though this approach reduces overall security posture by limiting key exchange options. The implementation of proper input validation and resource limits on cryptographic operations serves as an additional protective measure, aligning with ATT&CK technique T1499.004 which covers network disruption through resource exhaustion attacks. Organizations should also consider implementing intrusion detection systems capable of monitoring for anomalous TLS handshake patterns that might indicate exploitation attempts, and establish incident response procedures specifically addressing TLS-related DoS conditions to minimize operational impact during potential attacks.