CVE-2016-1881 in Retail Returns Management
Summary
by MITRE
The kernel in FreeBSD 9.3, 10.1, and 10.2 allows local users to cause a denial of service (crash) or potentially gain privilege via a crafted Linux compatibility layer setgroups system call.
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Analysis
by VulDB Data Team • 09/27/2022
The vulnerability identified as CVE-2016-1881 affects the FreeBSD kernel versions 9.3, 10.1, and 10.2, specifically within the Linux compatibility layer implementation. This issue stems from improper handling of the setgroups system call when executed through the Linux binary compatibility interface. The flaw exists in how the kernel processes certain parameters passed to the setgroups system call, creating a condition where malicious input can trigger unexpected behavior in the kernel's memory management subsystem. The vulnerability demonstrates characteristics of a buffer overflow condition and memory corruption issue, which can be exploited by local users to either crash the system or potentially escalate privileges.
The technical implementation of this vulnerability occurs within the Linux compatibility layer that FreeBSD provides to execute Linux binaries. When a Linux application invokes the setgroups system call, the FreeBSD kernel must translate this call into its native system call interface. The flaw manifests when the kernel fails to properly validate or process the group ID array passed to the system call, allowing malformed input to cause kernel memory corruption. This corruption can lead to kernel panics and system crashes, or in more sophisticated exploitation scenarios, potentially allow privilege escalation through controlled memory manipulation. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though it more accurately represents a heap-based memory corruption issue within the kernel's compatibility layer.
The operational impact of CVE-2016-1881 extends beyond simple denial of service, as local attackers with minimal privileges can potentially leverage this weakness to achieve privilege escalation. This vulnerability affects systems running FreeBSD 9.3, 10.1, and 10.2 where the Linux binary compatibility feature is enabled, which is commonly used in development environments and server configurations that require Linux application compatibility. The attack vector requires local access to the system, making it less severe than remote exploitation vulnerabilities, but still poses significant risk to system integrity and availability. The vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation techniques, and particularly relates to T1059 for execution of malicious code through system calls.
Mitigation strategies for CVE-2016-1881 primarily involve updating to patched FreeBSD versions where the vulnerability has been addressed through proper parameter validation and memory handling in the Linux compatibility layer. System administrators should disable the Linux binary compatibility feature if it is not required for operations, as this removes the attack surface entirely. Additionally, implementing proper access controls and monitoring for unusual system call patterns can help detect potential exploitation attempts. The fix implemented by FreeBSD developers involved strengthening input validation in the setgroups system call handler within the Linux compatibility layer, ensuring that group ID arrays are properly bounds-checked before processing. Security monitoring should focus on detecting abnormal kernel behavior and system crashes that may indicate exploitation attempts, particularly in environments where Linux compatibility is actively used.