CVE-2016-0266 in AIX
Summary
by MITRE
IBM AIX 5.3, 6.1, 7.1, and 7.2 and VIOS 2.2.x do not default to the latest TLS version, which makes it easier for man-in-the-middle attackers to obtain sensitive information via unspecified vectors.
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Analysis
by VulDB Data Team • 03/12/2019
The vulnerability identified as CVE-2016-0266 affects IBM AIX operating systems across multiple versions including 5.3, 6.1, 7.1, and 7.2 along with VIOS 2.2.x releases. This security flaw represents a critical configuration issue that undermines the cryptographic security posture of affected systems. The vulnerability stems from the default configuration of Transport Layer Security implementations within these operating systems, which fail to automatically utilize the most recent TLS protocol versions. This misconfiguration creates a significant attack surface that adversaries can exploit to conduct man-in-the-middle attacks against network communications.
The technical flaw manifests in the improper default configuration of TLS protocol versions, where systems do not automatically negotiate the highest available security protocols. This weakness allows attackers to downgrade connections to older, less secure TLS versions that are more susceptible to cryptographic attacks. The unspecified vectors mentioned in the description suggest that multiple attack pathways exist through which adversaries can exploit this vulnerability, potentially including protocol downgrade attacks, session hijacking, or credential interception. The vulnerability falls under CWE-319, which specifically addresses the exposure of sensitive information through improper use of cryptographic protocols, and aligns with ATT&CK technique T1046 which covers network service scanning and T1566 which covers credential harvesting through social engineering or network attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally weakens the cryptographic foundations of affected systems. Organizations running these vulnerable versions face increased risk of data breaches, unauthorized access to sensitive communications, and potential compromise of entire network infrastructures. The vulnerability is particularly concerning in enterprise environments where AIX systems often serve as critical infrastructure components, including database servers, application servers, and network services. Attackers can leverage this weakness to intercept communications between systems, potentially gaining access to confidential data, credentials, and business-critical information. The extended attack window created by this vulnerability means that even systems with proper network segmentation may be at risk if they communicate with vulnerable endpoints.
Mitigation strategies for CVE-2016-0266 require immediate configuration updates to enforce the use of modern TLS versions, specifically TLS 1.2 or higher, while disabling support for older, vulnerable protocols such as TLS 1.0 and SSL 3.0. System administrators should implement comprehensive patch management processes to ensure all affected AIX systems receive the appropriate security updates from IBM. Network administrators must also configure firewalls and security appliances to enforce TLS version compliance and monitor for protocol downgrade attempts. The implementation of these security controls should align with NIST SP 800-52 guidelines for secure configuration of TLS implementations and should be complemented by regular security audits to verify proper configuration. Organizations should also consider implementing network monitoring solutions that can detect and alert on suspicious protocol negotiation patterns, as this vulnerability often manifests through subtle protocol downgrade attacks that may not immediately trigger obvious security alerts.