CVE-2015-4550 in ASA
Summary
by MITRE
The Cavium cryptographic-module firmware on Cisco Adaptive Security Appliance (ASA) devices with software 9.3(3) and 9.4(1.1) does not verify the AES-GCM Integrity Check Value (ICV) octets, which makes it easier for man-in-the-middle attackers to spoof IPSec and IKEv2 traffic by modifying packet data, aka Bug ID CSCuu66218.
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Analysis
by VulDB Data Team • 05/21/2022
The vulnerability identified as CVE-2015-4550 represents a critical cryptographic flaw within the Cavium cryptographic module firmware deployed on Cisco Adaptive Security Appliance devices. This weakness specifically affects ASA software versions 9.3(3) and 9.4(1.1) where the implementation fails to properly validate the AES-GCM Integrity Check Value octets during cryptographic operations. The failure occurs at the fundamental level of authenticated encryption, where the integrity verification mechanism that should detect tampered data is effectively disabled or bypassed. This cryptographic failure creates a significant security gap that directly impacts the confidentiality, integrity, and authenticity guarantees that IPSec and IKEv2 protocols are designed to provide.
The technical flaw stems from improper implementation of the AES-GCM (Advanced Encryption Standard - Galois/Counter Mode) algorithm within the hardware cryptographic module. In standard AES-GCM implementations, the Integrity Check Value serves as a cryptographic checksum that ensures data has not been modified during transmission. When this verification is omitted or disabled, attackers can manipulate packet contents without detection, as the receiving end fails to validate that the data remains unaltered. The vulnerability specifically targets the cryptographic module's handling of ICV octets, which are critical components that provide authenticated encryption guarantees. This flaw falls under CWE-310, Cryptographic Issues, and more specifically aligns with CWE-327, Use of a Broken or Risky Cryptographic Algorithm, though the specific implementation error is more accurately categorized as a weakness in cryptographic implementation rather than algorithm selection.
The operational impact of this vulnerability is severe and directly enables man-in-the-middle attacks that can compromise the security of encrypted communications. Attackers can exploit this weakness to spoof IPSec and IKEv2 traffic by modifying packet data without being detected by the cryptographic verification mechanisms. This capability allows for traffic manipulation, data injection, and potential unauthorized access to sensitive communications that should remain protected. The vulnerability affects network security infrastructure components that rely on cryptographic integrity checks to maintain secure communication channels, potentially allowing attackers to establish unauthorized connections, modify encrypted data in transit, or bypass authentication mechanisms. The impact extends beyond simple data interception to include complete compromise of the cryptographic security model that IPSec and IKEv2 protocols are designed to provide, making this a critical vulnerability for network security operations.
Organizations affected by this vulnerability should implement immediate mitigations including software updates to patched versions of Cisco ASA software that properly implement AES-GCM integrity verification. The recommended approach involves upgrading to software versions that address the specific cryptographic implementation flaw in the Cavium module firmware. Network administrators should also consider implementing additional monitoring and detection measures to identify potential exploitation attempts, as the vulnerability allows for undetected traffic manipulation. Security teams should review their current IPSec and IKEv2 configurations to ensure that any affected devices are properly updated and that cryptographic integrity mechanisms are functioning correctly. The mitigation strategy should also include network segmentation and additional security controls to reduce the attack surface while waiting for comprehensive software patches. This vulnerability demonstrates the critical importance of proper cryptographic implementation and validation, as even minor flaws in cryptographic verification can completely undermine the security of encrypted communications.