CVE-2016-6249 in BIG-IP
Summary
by MITRE
F5 BIG-IP 12.0.0 and 11.5.0 - 11.6.1 REST requests which timeout during user account authentication may log sensitive attributes such as passwords in plaintext to /var/log/restjavad.0.log. It may allow local users to obtain sensitive information by reading these files.
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Analysis
by VulDB Data Team • 11/25/2024
The vulnerability identified as CVE-2016-6249 affects F5 BIG-IP appliances running specific versions including 12.0.0 and 11.5.0 through 11.6.1. This security flaw represents a critical information disclosure issue that stems from improper handling of authentication timeouts within the REST API framework. The vulnerability manifests when authentication requests time out during user account validation processes, creating a scenario where sensitive authentication data becomes inadvertently logged in plaintext format. The affected log file /var/log/restjavad.0.log contains these plaintext credentials, which poses significant security risks to organizations relying on F5 BIG-IP systems for their network infrastructure.
The technical mechanism behind this vulnerability involves the REST API implementation within F5 BIG-IP appliances where timeout conditions during authentication are not properly sanitized before logging operations. When authentication requests exceed the configured timeout thresholds, the system fails to strip or mask sensitive attributes such as passwords from the logged data. This occurs because the logging mechanism does not differentiate between normal operational data and sensitive authentication information, resulting in plaintext credential exposure within the system's log files. The flaw operates at the application layer and demonstrates poor input validation and output sanitization practices, which are categorized under CWE-20: Improper Input Validation and CWE-312: Cleartext Storage of Sensitive Information.
The operational impact of CVE-2016-6249 extends beyond simple credential exposure, as it creates persistent attack vectors that can be exploited by local users with access to the system's file system. Attackers who gain local access to the appliance can simply read the log files to obtain plaintext passwords, potentially compromising multiple user accounts and system access points. This vulnerability is particularly concerning because it affects the core authentication mechanisms of the BIG-IP system, potentially allowing attackers to escalate privileges or maintain persistent access to the network infrastructure. The exposure of plaintext credentials in log files creates a gold mine for attackers seeking to move laterally within networks and compromise additional systems that may share similar authentication credentials.
Organizations should implement immediate mitigations including restricting file system access to the log files, implementing proper log rotation and sanitization procedures, and applying the vendor-provided security patches. The mitigation strategy should align with ATT&CK framework techniques such as T1070.004 - Indicator Removal on Host and T1566.001 - Phishing, as attackers may attempt to exploit these credentials for further attacks. System administrators should also consider implementing monitoring solutions that can detect unauthorized access attempts to sensitive log files and establish proper access controls through the principle of least privilege. The vulnerability highlights the importance of secure logging practices and proper credential handling in enterprise security infrastructure, particularly in critical network components like load balancers and application delivery controllers that serve as gateways to organizational resources.