CVE-2014-3880 in FreeBSD
Summary
by MITRE
The (1) execve and (2) fexecve system calls in the FreeBSD kernel 8.4 before p11, 9.1 before p14, 9.2 before p7, and 10.0 before p4 destroys the virtual memory address space and mappings for a process before all threads have terminated, which allows local users to cause a denial of service (triple-fault and system reboot) via a crafted system call, which triggers an invalid page table pointer dereference.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability described in CVE-2014-3880 represents a critical flaw in the FreeBSD kernel's handling of process execution system calls, specifically affecting versions prior to their respective patch levels. This issue manifests in the execve and fexecve system calls where the kernel prematurely destroys virtual memory address space mappings and process structures before all threads within the process have completed execution. The flaw creates a race condition scenario that can be exploited by local attackers to trigger system instability through carefully crafted system calls. The vulnerability operates at the kernel level, making it particularly dangerous as it can lead to complete system compromise rather than just application-level issues.
The technical implementation of this vulnerability stems from improper synchronization between process termination and memory management operations within the FreeBSD kernel. When execve or fexecve is invoked, the kernel should ensure that all threads within the process have properly terminated before deallocating memory mappings. However, in the affected versions, this synchronization mechanism fails, causing the kernel to prematurely free memory structures while threads are still executing. This creates a scenario where subsequent memory accesses result in invalid page table pointer dereferences, leading to system crashes. The vulnerability specifically triggers what is known as a triple-fault condition, which occurs when the processor encounters multiple faults in rapid succession, ultimately forcing a system reboot as the processor cannot recover from such conditions.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be weaponized to create persistent system instability that affects all users and services running on the affected FreeBSD systems. Local attackers who can execute processes on the target system can leverage this vulnerability to repeatedly cause system reboots, effectively creating a persistent denial of service attack that can disrupt critical services and potentially cause data loss. The vulnerability affects multiple FreeBSD versions simultaneously, indicating a fundamental flaw in the kernel's memory management subsystem that was not properly addressed across the affected release branches. This makes the vulnerability particularly concerning for organizations running multiple FreeBSD versions in their infrastructure, as a single compromised system could potentially affect the entire network.
Mitigation strategies for CVE-2014-3880 require immediate patching of affected FreeBSD systems to the latest stable releases containing the necessary kernel fixes. Organizations should prioritize updating their FreeBSD installations to versions that include proper thread synchronization mechanisms for process execution system calls. Additionally, system administrators should implement monitoring solutions to detect unusual reboot patterns that could indicate exploitation attempts. The vulnerability aligns with CWE-362, which describes a race condition in concurrent systems, and can be classified under ATT&CK technique T1499.001 for endpoint denial of service attacks. Network segmentation and privilege separation can provide additional defense-in-depth measures, though the most effective mitigation remains timely patch management and system updates to address the underlying kernel memory management flaw that enables this vulnerability.