CVE-2014-4157 in Linux
Summary
by MITRE
arch/mips/include/asm/thread_info.h in the Linux kernel before 3.14.8 on the MIPS platform does not configure _TIF_SECCOMP checks on the fast system-call path, which allows local users to bypass intended PR_SET_SECCOMP restrictions by executing a crafted application without invoking a trace or audit subsystem.
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Analysis
by VulDB Data Team • 01/18/2022
The vulnerability described in CVE-2014-4157 represents a critical security flaw in the Linux kernel's implementation of seccomp (secure computing mode) functionality on MIPS architecture systems. This issue affects Linux kernel versions prior to 3.14.8 and specifically targets the MIPS platform where the kernel fails to properly enforce seccomp restrictions during fast system call execution paths. The flaw resides in the arch/mips/include/asm/thread_info.h file which controls how thread information is managed and how system call processing occurs. When a process attempts to set seccomp restrictions using prctl() with PR_SET_SECCOMP, the kernel should prevent unauthorized system calls from executing, but due to this implementation gap, these restrictions can be bypassed.
The technical nature of this vulnerability stems from the improper configuration of _TIF_SECCOMP flags within the MIPS kernel architecture's thread information structure. During normal system call processing, the kernel should check for seccomp restrictions before executing system calls, but in the affected versions, this check is skipped on the fast path for system calls. This creates a race condition where malicious applications can execute system calls that should have been blocked by seccomp policies. The vulnerability is particularly dangerous because it allows local users to bypass security restrictions without triggering the trace or audit subsystems that would normally detect such attempts, making the bypass more stealthy and harder to detect.
From an operational impact perspective, this vulnerability enables local privilege escalation and arbitrary code execution within the context of the compromised process. An attacker with local access can craft applications that exploit this weakness to circumvent security controls that were designed to limit system call execution. This effectively undermines the security model that seccomp was intended to provide, allowing malicious code to perform privileged operations that should be restricted. The vulnerability is especially concerning in environments where seccomp is used as a security boundary, such as web browsers, sandboxed applications, or containerized environments where process isolation is critical. The attack vector requires local access but can result in significant damage to system integrity and security posture.
The mitigation strategy for this vulnerability involves upgrading to Linux kernel version 3.14.8 or later where the proper _TIF_SECCOMP flag configuration has been implemented. System administrators should prioritize patching affected systems and verify that the kernel has been properly updated to include the necessary security fixes. Additionally, organizations should review their seccomp policy implementations to ensure that they are not relying on the vulnerable fast path for system call restrictions. This vulnerability aligns with CWE-284, which deals with improper access control, and relates to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' through local system vulnerabilities. Organizations should also consider implementing additional monitoring for unauthorized system call patterns and ensure that security policies are regularly audited to prevent similar issues from arising in other kernel components or architectures.