CVE-2014-3873 in FreeBSD
Summary
by MITRE
The ktrace utility in the FreeBSD kernel 8.4 before p11, 9.1 before p14, 9.2 before p7, and 9.3-BETA1 before p1 uses an incorrect page fault kernel trace entry size, which allows local users to obtain sensitive information from kernel memory via a kernel process trace.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability identified as CVE-2014-3873 affects the FreeBSD kernel's ktrace utility across multiple versions including 8.4 before p11, 9.1 before p14, 9.2 before p7, and 9.3-BETA1 before p1. This issue stems from an incorrect page fault kernel trace entry size calculation within the ktrace implementation, creating a significant information disclosure risk. The ktrace utility serves as a kernel tracing mechanism that allows processes to monitor system calls and other kernel activities, making it a critical component for system debugging and security auditing purposes.
The technical flaw manifests in how the ktrace utility handles page fault entries during kernel tracing operations. When a kernel process is being traced, the utility incorrectly calculates the size of page fault entries in the kernel trace buffer. This miscalculation leads to improper memory layout handling where the trace entries do not properly account for the actual memory addresses and data structures being accessed. The incorrect sizing causes the trace utility to read beyond the intended memory boundaries, potentially exposing kernel memory contents to local users who have access to the ktrace functionality.
This vulnerability represents a classic case of information disclosure through improper memory handling and buffer management. The flaw enables local attackers to obtain sensitive information from kernel memory, which could include cryptographic keys, passwords, or other confidential data that resides in kernel space. The attack vector requires local system access since ktrace is typically available to users with appropriate privileges, but the impact extends beyond simple privilege escalation to include potential data leakage that could compromise system security. According to CWE classification, this vulnerability maps to CWE-200 Information Exposure, specifically through improper handling of kernel memory structures.
The operational impact of CVE-2014-3873 is significant for FreeBSD systems that utilize ktrace functionality for debugging or monitoring purposes. Local users with access to the system can exploit this vulnerability to extract kernel memory contents, potentially revealing sensitive information that could be used for further exploitation or system compromise. The vulnerability affects systems where ktrace is actively used for process tracing, making it particularly concerning for security-sensitive environments where kernel memory analysis is common. Attackers could potentially leverage this information to understand kernel memory layouts, identify security weaknesses, or develop more sophisticated attacks against the target systems.
Mitigation strategies for this vulnerability include applying the appropriate FreeBSD security patches that correct the page fault entry size calculation in the ktrace utility. System administrators should ensure that all affected FreeBSD versions are updated to the patched releases, particularly focusing on the specific point releases mentioned in the vulnerability description. Additionally, organizations should review their ktrace usage policies and consider disabling or restricting access to ktrace functionality on systems where it is not essential for legitimate debugging or monitoring purposes. The ATT&CK framework categorizes this vulnerability under T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it allows local users to gain unauthorized access to kernel memory through legitimate system utilities. Regular security audits should include verification that ktrace is not unnecessarily enabled on production systems, and monitoring should be implemented to detect unusual ktrace activity that might indicate exploitation attempts.