CVE-2014-1874 in Linux
Summary
by MITRE
The security_context_to_sid_core function in security/selinux/ss/services.c in the Linux kernel before 3.13.4 allows local users to cause a denial of service (system crash) by leveraging the CAP_MAC_ADMIN capability to set a zero-length security context.
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Analysis
by VulDB Data Team • 04/12/2025
The vulnerability identified as CVE-2014-1874 resides within the Linux kernel's Security-Enhanced Linux (SELinux) subsystem, specifically in the security_context_to_sid_core function located in security/selinux/ss/services.c. This flaw represents a critical denial of service vulnerability that can be exploited by local attackers who possess the CAP_MAC_ADMIN capability, which is typically available to processes with elevated privileges or specific security contexts. The vulnerability stems from inadequate input validation within the SELinux security services module, where the function fails to properly handle zero-length security contexts, leading to a system crash or kernel panic.
The technical implementation of this vulnerability involves the manipulation of SELinux security contexts through the CAP_MAC_ADMIN capability, which grants processes the ability to modify security policies and security contexts. When a local user with this capability attempts to set a security context with zero length, the security_context_to_sid_core function does not validate the context length before processing it, resulting in a buffer over-read or memory corruption condition. This condition occurs because the function assumes a minimum context length and attempts to parse memory regions that may not contain valid security context data, ultimately causing the kernel to crash when it encounters the malformed input.
The operational impact of this vulnerability extends beyond simple system availability concerns, as it can be leveraged to disrupt critical system services and potentially provide a foothold for further exploitation. Attackers can utilize this vulnerability to repeatedly crash the system, creating persistent denial of service conditions that may be difficult to detect and remediate. The vulnerability is particularly concerning because it requires minimal privileges to exploit, as the CAP_MAC_ADMIN capability is often available to processes running with elevated permissions or within specific security domains. This makes the vulnerability exploitable in various scenarios including privilege escalation attempts and system stability attacks.
Mitigation strategies for CVE-2014-1874 focus primarily on kernel version updates and privilege restriction measures. Organizations should immediately upgrade to Linux kernel versions 3.13.4 or later, which contain the necessary patches to address the zero-length context handling issue. Additionally, system administrators should review and minimize the use of CAP_MAC_ADMIN capabilities, ensuring that only trusted processes have access to this powerful privilege. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and can be classified under ATT&CK technique T1068, which involves exploiting privileges to escalate access. Security monitoring should include detection of unusual kernel crashes and suspicious use of MAC capabilities, while incident response procedures should account for potential privilege escalation vectors that may be masked by this denial of service condition.