CVE-2019-5614 in FreeBSD
Summary
by MITRE
In FreeBSD 12.1-STABLE before r356035, 12.1-RELEASE before 12.1-RELEASE-p4, 11.3-STABLE before r356036, and 11.3-RELEASE before 11.3-RELEASE-p8, incomplete packet data validation may result in accessing out-of-bounds memory leading to a kernel panic or other unpredictable results.
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Analysis
by VulDB Data Team • 10/14/2020
This vulnerability exists within the FreeBSD kernel networking stack where insufficient validation of packet data during network processing can lead to memory access violations. The flaw affects multiple FreeBSD release versions including 12.1-STABLE before r356035 and 11.3-STABLE before r356036, with respective patched releases 12.1-RELEASE-p4 and 11.3-RELEASE-p8. The issue manifests when the kernel processes network packets without proper bounds checking on packet data structures, creating opportunities for out-of-bounds memory access that can result in system instability or unpredictable behavior.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the kernel's network packet handling routines. When network packets arrive at the kernel level, they undergo processing that includes parsing various packet headers and payload data. The insufficient validation allows maliciously crafted packets to bypass normal bounds checking procedures, potentially causing the kernel to access memory locations outside the intended packet data boundaries. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, which is classified as a critical security weakness in software systems. The vulnerability represents a classic buffer over-read condition where the kernel attempts to read beyond the allocated memory boundaries of packet data structures.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more sophisticated attack vectors. A remote attacker could exploit this weakness to cause kernel panics, leading to denial of service conditions that could disrupt network services and system availability. The unpredictable results mentioned in the vulnerability description suggest that under certain conditions, this flaw might also enable privilege escalation or information disclosure scenarios, though the primary risk remains system instability and denial of service. This vulnerability directly relates to the ATT&CK technique T1499.004 which covers Network Denial of Service, and could potentially map to T1068 for local privilege escalation if exploitation leads to kernel code execution.
Mitigation strategies for this vulnerability should focus on immediate patch deployment across all affected FreeBSD systems to ensure proper bounds checking is enforced during packet processing. System administrators should prioritize updating to the patched releases mentioned in the advisory, specifically 12.1-RELEASE-p4 and 11.3-RELEASE-p8, to address the root cause of the memory validation issues. Network monitoring should be enhanced to detect unusual packet patterns that might indicate exploitation attempts, while also implementing proper network segmentation and firewall rules to limit exposure to potentially malicious traffic. Additionally, organizations should consider implementing kernel hardening measures such as stack canaries, address space layout randomization, and other exploit mitigation techniques to reduce the overall attack surface and potential impact of similar vulnerabilities that may exist in the networking stack.