CVE-2014-3215 in policycoreutils
Summary
by MITRE
seunshare in policycoreutils 2.2.5 is owned by root with 4755 permissions, and executes programs in a way that changes the relationship between the setuid system call and the getresuid saved set-user-ID value, which makes it easier for local users to gain privileges by leveraging a program that mistakenly expected that it could permanently drop privileges.
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Analysis
by VulDB Data Team • 03/21/2022
The vulnerability described in CVE-2014-3215 resides within the seunshare utility component of policycoreutils version 2.2.5, presenting a critical privilege escalation risk for local attackers. This utility is designed to handle unsharing of namespaces in SELinux environments, but its implementation contains a fundamental flaw that undermines the security model's integrity. The seunshare binary is installed with setuid root permissions, specifically 4755, which allows any user to execute it with elevated privileges. This configuration is standard for utilities that need to perform privileged operations while maintaining user-level execution contexts.
The core technical flaw involves the improper handling of the setuid mechanism during program execution. When seunshare executes programs, it manipulates the relationship between the setuid system call and the getresuid saved set-user-ID value in a manner that violates expected security behaviors. The system call semantics are altered such that the saved set-user-ID value does not properly reflect the intended privilege levels after execution. This deviation from standard setuid behavior creates a window where programs that rely on predictable privilege dropping mechanisms can be exploited. The vulnerability specifically affects programs that mistakenly expect the setuid system call to function in its conventional manner, where privileges can be permanently dropped after initial elevation.
The operational impact of this vulnerability is severe for systems running affected versions of policycoreutils. Local attackers can leverage this flaw to bypass privilege separation mechanisms that are fundamental to SELinux's security model. The exploitation process typically involves crafting a malicious program that depends on the standard setuid behavior, then using seunshare to execute it in a context where privilege dropping fails to occur as expected. This allows attackers to maintain elevated privileges beyond what would normally be permitted, effectively creating a persistent backdoor for privilege escalation. The vulnerability is particularly dangerous because it operates at the kernel level through the SELinux subsystem, making it difficult to detect and isolate.
Mitigation strategies for CVE-2014-3215 require immediate system updates to patched versions of policycoreutils, which address the core issue in seunshare's privilege handling. Organizations should also implement comprehensive monitoring for unauthorized setuid binary execution and establish strict access controls for the affected utility. The vulnerability aligns with CWE-276, which covers improper privilege management, and corresponds to ATT&CK technique T1068, involving privilege escalation through local exploitation. System administrators must ensure that all SELinux-related packages are kept current and that proper security auditing is performed to detect any unauthorized modifications to setuid binaries. Additionally, implementing mandatory access controls and regular security assessments can help prevent exploitation of similar vulnerabilities in the broader system landscape.