CVE-2004-1066 in FreeBSD
Summary
by MITRE
The cmdline pseudofiles in (1) procfs on FreeBSD 4.8 through 5.3, and (2) linprocfs on FreeBSD 5.x through 5.3, do not properly validate a process argument vector, which allows local users to cause a denial of service (panic) or read portions of kernel memory. NOTE: this candidate might be SPLIT into 2 separate items in the future.
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Analysis
by VulDB Data Team • 03/10/2021
The vulnerability described in CVE-2004-1066 represents a critical flaw in the FreeBSD operating system's process management subsystem, specifically within the pseudo-file systems that provide process information to userspace. This issue affects FreeBSD versions 4.8 through 5.3 for procfs and 5.x through 5.3 for linprocfs, creating a pathway for local attackers to exploit kernel memory access through malformed process argument vectors. The vulnerability stems from insufficient input validation mechanisms within the kernel's handling of command line arguments, which are typically exposed through these pseudo-file interfaces for debugging and monitoring purposes.
The technical implementation of this vulnerability involves the improper validation of process argument vectors when these are accessed through the procfs or linprocfs file systems. When a local user attempts to read the command line information of a process, the kernel fails to properly sanitize the argument vector data before exposing it to userspace. This lack of validation creates two distinct attack vectors: one that can trigger a kernel panic leading to system denial of service, and another that allows unauthorized memory reading from kernel space. The flaw specifically manifests in how the kernel processes and formats the argv array when generating the pseudo-file content, particularly when dealing with malformed or excessively long argument strings that exceed expected boundaries.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a serious privilege escalation risk within the kernel context. Local attackers can leverage this flaw to gain unauthorized access to kernel memory regions, potentially extracting sensitive information or causing system instability that could lead to complete system compromise. The vulnerability affects system stability across multiple FreeBSD versions, creating a widespread risk for organizations running these older releases. From an attack perspective, this represents a local privilege escalation vector that aligns with ATT&CK technique T1068, specifically targeting kernel vulnerabilities for privilege escalation, and maps to CWE-125, which addresses out-of-bounds read conditions in kernel code.
Mitigation strategies for CVE-2004-1066 require immediate system updates to patched FreeBSD versions that address the argument vector validation issues in both procfs and linprocfs implementations. System administrators should prioritize upgrading to FreeBSD 5.4 or later releases where these vulnerabilities have been resolved through proper input validation mechanisms. Additionally, implementing kernel hardening measures such as disabling unnecessary pseudo-file systems, restricting access permissions on procfs entries, and monitoring for unusual process argument patterns can help reduce the attack surface. Organizations should also consider implementing process monitoring solutions that can detect anomalous behavior related to kernel memory access patterns, as this vulnerability could potentially be exploited as part of broader attack chains targeting system stability and information disclosure. The vulnerability serves as a reminder of the importance of proper input validation in kernel space and demonstrates how seemingly benign interfaces can become critical attack vectors when insufficient validation is implemented.