CVE-2015-5738 in Cavium
Summary
by MITRE
The RSA-CRT implementation in the Cavium Software Development Kit (SDK) 2.x, when used on OCTEON II CN6xxx Hardware on Linux to support TLS with Perfect Forward Secrecy (PFS), makes it easier for remote attackers to obtain private RSA keys by conducting a Lenstra side-channel attack.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability described in CVE-2015-5738 represents a critical security flaw in the cryptographic implementation of the Cavium Software Development Kit version 2.x, specifically affecting hardware platforms based on the OCTEON II CN6xxx architecture running Linux operating systems. This issue manifests when the SDK is employed to implement TLS connections with Perfect Forward Secrecy capabilities, creating a scenario where attackers can exploit timing variations in cryptographic operations to compromise private RSA key material.
The technical root cause of this vulnerability lies in the RSA-CRT (Chinese Remainder Theorem) implementation within the Cavium SDK, which exhibits side-channel characteristics that leak information about the private key during cryptographic operations. The vulnerability is particularly concerning because it enables remote attackers to perform Lenstra side-channel attacks, a sophisticated method that exploits timing variations in modular exponentiation operations to recover private key components. This weakness occurs specifically when the SDK is configured to use the OCTEON II CN6xxx hardware platform, where the cryptographic operations do not adequately mask timing variations that would normally be present in standard RSA-CRT implementations.
The operational impact of this vulnerability extends beyond simple cryptographic compromise, as it fundamentally undermines the security assurances provided by TLS connections with Perfect Forward Secrecy. Attackers can leverage this weakness to obtain private RSA keys that are used to establish secure communications, potentially enabling them to decrypt previously captured network traffic, impersonate legitimate services, or conduct man-in-the-middle attacks against vulnerable systems. The remote nature of the attack means that adversaries do not require physical access to the target hardware, making this vulnerability particularly dangerous in cloud environments or distributed systems where such hardware may be deployed across multiple locations.
This vulnerability aligns with CWE-310, which addresses cryptographic weaknesses, specifically focusing on side-channel attacks that exploit implementation flaws rather than theoretical cryptographic weaknesses. The attack vector corresponds to the ATT&CK technique T1583.001, which involves the exploitation of weaknesses in cryptographic implementations to obtain sensitive information. Organizations utilizing Cavium hardware platforms with the affected SDK version face significant risk, as the vulnerability can be exploited by attackers with minimal resources and no specialized hardware requirements. The implications extend to any system that relies on RSA key material for TLS operations, potentially affecting web servers, database servers, and other infrastructure components that implement secure communication protocols.
Mitigation strategies for this vulnerability require immediate action including updating to a patched version of the Cavium SDK that properly implements constant-time cryptographic operations to prevent timing variations from leaking information. Organizations should also consider implementing additional cryptographic protections such as using different key exchange algorithms that are less susceptible to side-channel attacks, or deploying hardware security modules that provide dedicated cryptographic processing with built-in side-channel resistance. The vulnerability underscores the importance of proper cryptographic implementation practices and the need for thorough security testing of cryptographic components, particularly in hardware-based cryptographic solutions where timing variations can create exploitable side channels.