CVE-2015-4458 in ASA
Summary
by MITRE
The TLS implementation in the Cavium cryptographic-module firmware, as distributed with Cisco Adaptive Security Appliance (ASA) Software 9.1(5.21) and other products, does not verify the MAC field, which allows man-in-the-middle attackers to spoof TLS content by modifying packets, aka Bug ID CSCuu52976.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability described in CVE-2015-4458 represents a critical flaw in the Transport Layer Security implementation within Cavium cryptographic-module firmware used by Cisco Adaptive Security Appliance software versions 9.1(5.21) and related products. This weakness specifically targets the message authentication code verification process during TLS protocol execution, creating a fundamental security gap that undermines the integrity protection mechanisms designed to prevent unauthorized modifications to encrypted communications. The flaw exists at the firmware level of hardware cryptographic modules manufactured by Cavium, which are integrated into Cisco security appliances to provide cryptographic services including TLS termination and encryption processing. The vulnerability is particularly concerning because it affects the core security infrastructure of network devices that handle sensitive communications and are deployed in enterprise and government environments where secure data transmission is paramount.
The technical root cause of this vulnerability lies in the improper implementation of the TLS protocol's message authentication code verification mechanism within the Cavium firmware. During TLS handshake and data transmission processes, the cryptographic module should validate the MAC field to ensure that data has not been tampered with during transit. However, the flawed implementation fails to perform this critical verification step, allowing attackers to modify packet contents without detection. This represents a direct violation of the cryptographic integrity principles that TLS is designed to enforce, where the MAC field serves as a cryptographic checksum to verify that messages have not been altered. The vulnerability creates a scenario where an attacker positioned between communicating parties can intercept TLS traffic and modify packet contents, including application data, headers, or even protocol control information, without the receiving end detecting the modifications. This flaw operates at the protocol implementation level and specifically affects the cryptographic module's handling of TLS traffic, making it particularly dangerous for security-sensitive environments.
The operational impact of this vulnerability extends far beyond simple data integrity concerns, as it fundamentally compromises the security assurances provided by TLS encryption. An attacker exploiting this vulnerability can perform man-in-the-middle attacks with significant operational consequences, including data theft, session hijacking, and unauthorized access to sensitive communications. The ability to spoof TLS content means that malicious actors can modify encrypted traffic in transit, potentially injecting malicious content, redirecting communications, or extracting confidential information without detection. This vulnerability affects not just individual connections but entire security infrastructures that rely on TLS for protecting sensitive data flows. The impact is particularly severe for organizations using Cisco ASA appliances for VPN connections, secure web gateways, and other security services that depend on proper TLS implementation. The vulnerability affects the core security services of the appliance, potentially allowing attackers to bypass security controls and gain unauthorized access to protected networks and data.
Organizations affected by this vulnerability should implement immediate mitigations including firmware updates from Cisco to address the Cavium firmware flaw, network segmentation to limit exposure, and enhanced monitoring for suspicious traffic patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-310, which covers cryptographic weaknesses in message authentication code implementation, and represents a clear violation of the TLS protocol specifications that require proper integrity verification. From an attacker perspective, this vulnerability maps to ATT&CK technique T1041, which involves data compression and encryption, and T1566, which covers credential access through social engineering or network attacks. The remediation process should include comprehensive testing of updated firmware in controlled environments before deployment to ensure compatibility with existing security configurations. Organizations should also consider implementing additional security controls such as certificate pinning, enhanced network monitoring, and regular security assessments to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper cryptographic implementation and highlights the risks associated with hardware-based cryptographic modules that may contain implementation flaws not immediately apparent during initial security assessments.