CVE-2014-8476 in FreeBSD
Summary
by MITRE
The setlogin function in FreeBSD 8.4 through 10.1-RC4 does not initialize the buffer used to store the login name, which allows local users to obtain sensitive information from kernel memory via a call to getlogin, which returns the entire buffer.
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Analysis
by VulDB Data Team • 02/24/2022
The vulnerability identified as CVE-2014-8476 represents a critical information disclosure flaw within the FreeBSD operating system kernel. This issue affects versions ranging from 8.4 through 10.1-RC4, creating a persistent security weakness that could be exploited by local attackers to access sensitive data stored in kernel memory. The vulnerability stems from improper buffer initialization within the setlogin function, which is part of the system's authentication and session management framework. When a process calls setlogin to establish a login name for the current session, the function fails to properly clear or initialize the underlying buffer before storing the new login name. This initialization failure creates a scenario where remnants of previously stored data may persist in the buffer, potentially containing sensitive information from prior operations or system states.
The technical exploitation of this vulnerability occurs through the getlogin system call, which retrieves the login name associated with the current session. Due to the uninitialized buffer state, getlogin returns not only the intended login name but also the residual data that remains in the buffer from previous operations. This creates a situation where attackers can harvest sensitive information including but not limited to authentication tokens, session identifiers, system paths, or other confidential data that may have been temporarily stored in the kernel memory space. The flaw is particularly concerning because it operates at the kernel level, making it accessible to any local user who can execute the setlogin and getlogin functions, thereby bypassing typical user-space security boundaries and potentially exposing system internals that should remain protected.
The operational impact of CVE-2014-8476 extends beyond simple information disclosure, as the leaked kernel memory data could potentially contain sufficient information to aid in more sophisticated attacks. Attackers could leverage this information to perform privilege escalation attempts, bypass security mechanisms, or conduct further reconnaissance to identify system configurations and potential additional vulnerabilities. The vulnerability aligns with CWE-128, which addresses "Wraparound Error" in buffer operations, and represents a classic case of uninitialized memory exposure that violates fundamental security principles. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1003.001 for Credential Dumping, as the leaked information could include authentication-related data that might be used to compromise system security. The impact is particularly severe in multi-user environments where local users may attempt to gain unauthorized access to information belonging to other users or system processes.
The remediation for this vulnerability requires immediate patching of affected FreeBSD systems to ensure proper buffer initialization within the setlogin function. System administrators should prioritize updating to patched versions of FreeBSD that address this specific memory handling issue, as the vulnerability cannot be effectively mitigated through configuration changes alone. Additionally, organizations should implement monitoring for unusual patterns of getlogin usage that might indicate exploitation attempts, and consider implementing kernel memory protection mechanisms to limit information exposure. The fix typically involves ensuring that the buffer used by setlogin is properly initialized before storing new login information, preventing the leakage of residual data that could be retrieved through subsequent getlogin calls. Regular security audits and kernel memory analysis should be conducted to identify similar uninitialized memory patterns that might exist in other system components, as this vulnerability demonstrates the importance of proper memory management in kernel space operations.