CVE-2015-0536 in RSA BSAFE Micro Edition Suite
Summary
by MITRE
EMC RSA BSAFE Micro Edition Suite (MES) 4.0.x before 4.0.8 and 4.1.x before 4.1.3 and RSA BSAFE SSL-C 2.8.9 and earlier, when client authentication and an ephemeral Diffie-Hellman ciphersuite are enabled, allow remote attackers to cause a denial of service (daemon crash) via a ClientKeyExchange message with a length of zero, a similar issue to CVE-2015-1787.
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Analysis
by VulDB Data Team • 06/12/2022
The vulnerability identified as CVE-2015-0536 affects EMC RSA BSAFE Micro Edition Suite versions 4.0.x prior to 4.0.8 and 4.1.x prior to 4.1.3, as well as RSA BSAFE SSL-C version 2.8.9 and earlier. This security flaw specifically targets implementations that utilize client authentication combined with ephemeral Diffie-Hellman ciphersuites within the SSL/TLS protocol stack. The issue manifests when a malicious remote attacker crafts a specially formatted ClientKeyExchange message with a length of zero, causing the affected daemon process to crash and resulting in a denial of service condition. This vulnerability represents a classic buffer overflow or input validation weakness that exploits improper handling of cryptographic handshake messages during secure communications establishment.
The technical flaw stems from inadequate validation of the ClientKeyExchange message length within the cryptographic library implementation. When the SSL/TLS handshake process encounters a ClientKeyExchange message with zero length, the system fails to properly validate this input before processing it, leading to memory corruption or invalid pointer dereference conditions. This weakness falls under CWE-129, which describes improper validation of array indices, and CWE-248, which covers exposure of an exception to an application. The vulnerability is particularly dangerous because it occurs during the critical handshake phase of SSL/TLS communication, where the system is already in a vulnerable state due to the incomplete cryptographic negotiation process.
Operationally, this vulnerability presents significant risk to organizations relying on RSA BSAFE libraries for secure communications, particularly those implementing mutual SSL authentication with ephemeral Diffie-Hellman ciphersuites. The denial of service impact can disrupt critical services, including web applications, database connections, and enterprise communication systems that depend on secure SSL/TLS connections. Attackers can exploit this weakness with minimal resources to cause service disruption, making it particularly attractive for denial of service attacks. The vulnerability's similarity to CVE-2015-1787 indicates a broader pattern of implementation flaws in cryptographic libraries that handle ephemeral key exchanges, suggesting potential for cascading effects across multiple systems using similar cryptographic implementations.
Mitigation strategies for this vulnerability include immediate patching of affected systems to the recommended versions of RSA BSAFE Micro Edition Suite and SSL-C libraries, specifically versions 4.0.8 and 4.1.3 or later for the MES suite, and 2.8.10 or later for SSL-C. Organizations should also consider implementing network-level protections such as intrusion detection systems that can identify and block malformed ClientKeyExchange messages, though this represents a secondary defense mechanism. Additionally, system administrators should review their SSL/TLS configurations to disable ephemeral Diffie-Hellman ciphersuites if they are not strictly required for business operations, thereby eliminating the attack surface. The remediation approach aligns with ATT&CK technique T1499.004, which involves disrupting availability through denial of service attacks, requiring defensive measures to maintain system availability and prevent exploitation of cryptographic library weaknesses. Organizations should also implement comprehensive monitoring of SSL/TLS handshake failures and anomalous connection patterns that may indicate exploitation attempts.