CVE-2001-1166 in FreeBSD
Summary
by MITRE
linprocfs on FreeBSD 4.3 and earlier does not properly restrict access to kernel memory, which allows one process with debugging rights on a privileged process to read restricted memory from that process.
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Analysis
by VulDB Data Team • 02/11/2017
The vulnerability identified as CVE-2001-1166 resides within the linprocfs implementation on FreeBSD versions 4.3 and earlier, representing a critical access control flaw that undermines system security boundaries. This issue specifically affects the process filesystem interface that provides debugging capabilities to authorized processes, creating an avenue for unauthorized memory access. The flaw stems from inadequate validation mechanisms within the kernel memory access controls, allowing processes with debugging privileges to bypass normal protection schemes and extract sensitive kernel data from privileged processes.
The technical nature of this vulnerability aligns with CWE-284, which addresses improper access control in software systems. The root cause involves the linprocfs subsystem failing to properly validate memory access requests from debugging processes, enabling what is effectively a privilege escalation attack vector. When a process possesses debugging rights on a target privileged process, the system should enforce strict memory access boundaries, but instead allows unrestricted reading of kernel memory segments that should remain protected. This represents a fundamental breakdown in the kernel's memory protection mechanisms, where the debugging interface becomes a conduit for information disclosure rather than a controlled diagnostic tool.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to kernel memory contents that may contain sensitive data structures, cryptographic keys, or system configuration details. An attacker with debugging privileges on a privileged process can exploit this flaw to extract kernel memory, potentially leading to complete system compromise through the acquisition of sensitive kernel data. The vulnerability particularly affects systems where debugging capabilities are exposed to untrusted users or where privilege escalation is possible, as it transforms legitimate debugging functionality into a weapon for memory reconnaissance. This flaw can be leveraged to bypass other security controls by obtaining kernel-level information that would otherwise remain protected.
Mitigation strategies for CVE-2001-1166 require immediate system updates to FreeBSD versions that address the linprocfs access control issues, as the vulnerability represents a fundamental flaw in the kernel's memory protection architecture. System administrators should implement strict privilege controls to limit debugging access to only trusted processes and users, following the principle of least privilege as outlined in security best practices. The implementation of additional monitoring mechanisms to detect unauthorized debugging activities and memory access attempts can provide early warning of exploitation attempts. Organizations should also consider disabling linprocfs functionality when not required for debugging purposes, as this reduces the attack surface for this specific vulnerability. The remediation process should include comprehensive system auditing to identify processes with unnecessary debugging privileges and ensure that access controls are properly configured according to security frameworks and operational requirements.