CVE-2019-5607 in FreeBSD
Summary
by MITRE
In FreeBSD 12.0-STABLE before r350222, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r350223, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, rights transmitted over a domain socket did not properly release a reference on transmission error allowing a malicious user to cause the reference counter to wrap, forcing a free event. This could allow a malicious local user to gain root privileges or escape from a jail.
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Analysis
by VulDB Data Team • 11/13/2023
This vulnerability exists in FreeBSD kernel versions prior to specific release points and relates to improper handling of reference counting during domain socket operations. The flaw occurs when rights are transmitted over domain sockets and a transmission error occurs, leading to incorrect reference counter management. According to CWE-129, this represents an improper input validation issue that can result in arbitrary code execution. The vulnerability is classified under ATT&CK technique T1068 which involves exploiting local privileges to escalate to root access. The core technical issue involves the kernel's reference counting mechanism failing to properly decrement reference counters when transmission errors occur, creating a scenario where the reference counter can overflow and wrap around to zero, triggering an unintended free operation.
The operational impact of this vulnerability is severe as it allows local users to exploit a privilege escalation path that could lead to complete system compromise. When the reference counter wraps around due to the improper release of references, it can cause a memory management error that malicious users can manipulate to execute arbitrary code with elevated privileges. The vulnerability specifically affects systems running FreeBSD 12.0-STABLE before r350222, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r350223, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12. This represents a critical security flaw that undermines the integrity of the kernel's memory management subsystem and can be exploited to escape from restricted environments such as jails. The attack vector requires local system access but provides significant privileges escalation capabilities.
Mitigation strategies for this vulnerability involve applying the appropriate FreeBSD security patches that address the reference counting implementation in domain socket operations. System administrators should upgrade to the patched versions of FreeBSD releases including 12.0-RELEASE-p8, 11.3-RELEASE-p1, and 11.2-RELEASE-p12. The fix involves correcting the reference counting logic to ensure that reference counters are properly decremented even when transmission errors occur, preventing the counter wraparound condition. Additionally, implementing proper access controls and monitoring for unusual reference counting patterns can help detect potential exploitation attempts. Network administrators should also consider implementing additional security controls such as mandatory access controls, process monitoring, and regular security audits to reduce the attack surface and detect any potential exploitation attempts. Organizations running FreeBSD systems should also ensure that all domain socket operations are properly audited and that proper privilege separation is maintained to minimize the impact of such vulnerabilities.