CVE-2016-6883 in MatrixSSL
Summary
by MITRE
MatrixSSL before 3.8.3 configured with RSA Cipher Suites allows remote attackers to obtain sensitive information via a Bleichenbacher variant attack.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2016-6883 represents a critical security flaw in MatrixSSL versions prior to 3.8.3 that specifically affects systems configured with RSA cipher suites. This vulnerability stems from an implementation weakness in the SSL/TLS protocol handling that enables attackers to exploit a well-known cryptographic attack vector. The issue manifests when the SSL library processes RSA-based cipher suites and fails to properly validate cryptographic operations, creating opportunities for adversaries to extract sensitive information from the system.
The technical flaw exploited in this vulnerability is a variant of the Bleichenbacher attack, which targets the PKCS#1 v1.5 padding scheme used in RSA encryption. This particular variant allows attackers to perform a timing-based side-channel analysis against the SSL implementation, enabling them to gradually reconstruct private keys or session information through multiple decryption attempts. The attack leverages the fact that MatrixSSL did not implement proper constant-time operations or adequate padding validation mechanisms when processing RSA-encrypted data during the SSL handshake process. This weakness falls under the category of cryptographic implementation flaws that are commonly categorized as CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions.
The operational impact of this vulnerability is significant as it allows remote attackers to compromise the confidentiality of encrypted communications without requiring direct access to the target system. Attackers can exploit this vulnerability to recover sensitive information such as session keys, private keys, or other cryptographic material that would normally remain protected during SSL/TLS communication. The attack can be executed over the network without authentication requirements, making it particularly dangerous in environments where SSL/TLS is used to protect sensitive data transmission. This vulnerability directly affects the integrity of the cryptographic protection mechanisms that organizations rely upon to secure their communications.
Organizations affected by this vulnerability should immediately upgrade to MatrixSSL version 3.8.3 or later, which includes proper protections against Bleichenbacher-style attacks through the implementation of constant-time cryptographic operations and improved padding validation. Additional mitigations include configuring systems to avoid RSA cipher suites in favor of more secure alternatives such as those based on elliptic curve cryptography, implementing proper network segmentation to limit exposure, and monitoring for unusual network traffic patterns that might indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1573.002 which covers the use of secure communication protocols for data exfiltration, and represents a clear example of how improper cryptographic implementation can lead to severe security consequences. The attack vector specifically targets the SSL/TLS handshake process, making it particularly relevant to network security monitoring and incident response procedures that focus on cryptographic protocol analysis.