CVE-2015-0535 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 do not properly restrict TLS state transitions, which makes it easier for remote attackers to conduct cipher-downgrade attacks to EXPORT_RSA ciphers via crafted TLS traffic, related to the "FREAK" issue, a similar issue to CVE-2015-0204.
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Analysis
by VulDB Data Team • 06/12/2022
The vulnerability identified as CVE-2015-0535 represents a critical weakness in cryptographic protocol implementation within EMC RSA BSAFE Micro Edition Suite and RSA BSAFE SSL-C products. This flaw specifically targets the TLS state transition mechanisms that govern how secure connections negotiate and establish cryptographic parameters. The vulnerability enables attackers to manipulate the TLS handshake process, creating opportunities for man-in-the-middle attacks that can downgrade encryption strength to insecure EXPORT_RSA ciphers. This issue directly relates to the widely publicized FREAK vulnerability, which demonstrated how improper implementation of cryptographic negotiation could be exploited to weaken security protocols. The vulnerability affects multiple versions of the RSA BSAFE libraries, including MES 4.0.x before 4.0.8 and 4.1.x before 4.1.3, as well as RSA BSAFE SSL-C 2.8.9 and earlier versions, making it a widespread concern across various cryptographic implementations.
The technical flaw manifests in the improper restriction of TLS state transitions, where the cryptographic libraries fail to adequately validate or enforce the security parameters during the TLS handshake process. This weakness allows remote attackers to inject malicious TLS messages that manipulate the negotiation process, forcing connections to use weaker cryptographic algorithms. The specific vulnerability enables cipher-downgrade attacks that target the EXPORT_RSA cipher suite, which was designed for export restrictions in earlier cryptographic standards but has since been deemed insecure due to its weak key length and susceptibility to brute-force attacks. The flaw operates at the protocol level, specifically within the TLS implementation where state transitions should enforce minimum security requirements, but instead permit downgrade to compromised cryptographic strengths. This vulnerability directly maps to CWE-327, which addresses the use of insecure or weak cryptographic algorithms, and demonstrates how improper implementation of cryptographic protocol state machines can create exploitable conditions.
The operational impact of CVE-2015-0535 is significant, as it enables attackers to conduct sophisticated cipher-downgrade attacks that can compromise the confidentiality and integrity of encrypted communications. Remote attackers can leverage this vulnerability to force connections to use EXPORT_RSA ciphers, which typically employ 512-bit RSA keys that are vulnerable to modern computational attacks. The vulnerability creates a pathway for attackers to intercept and potentially decrypt communications, undermining the fundamental security guarantees that TLS is designed to provide. Organizations using affected versions of RSA BSAFE libraries may experience data breaches, unauthorized access to sensitive information, and potential compliance violations, particularly in environments where strong cryptographic protection is required. The vulnerability's similarity to CVE-2015-0204, which also addressed FREAK-related issues, indicates that the problem stems from broader implementation weaknesses in cryptographic libraries rather than isolated incidents, suggesting that organizations may need to conduct comprehensive security assessments of their cryptographic implementations.
Mitigation strategies for CVE-2015-0535 should prioritize immediate patching of affected systems with updated versions of RSA BSAFE libraries that properly enforce TLS state transitions and prevent cipher-downgrade attacks. Organizations should implement network monitoring to detect and alert on suspicious TLS handshake patterns that may indicate exploitation attempts. Security configurations should be reviewed to disable support for weak cryptographic algorithms and ensure that only strong cipher suites are permitted in TLS negotiations. The implementation of proper TLS security policies that enforce minimum cryptographic strength requirements can help prevent exploitation of this vulnerability. Additionally, organizations should consider implementing certificate pinning mechanisms and enhanced network segmentation to limit the potential impact of successful attacks. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1046 Network Service Scanning and T1566 Phishing, as attackers may need to identify vulnerable systems before exploiting the cryptographic weakness. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar implementation weaknesses in cryptographic libraries and protocols.