CVE-2004-0602 in FreeBSD
Summary
by MITRE
The binary compatibility mode for FreeBSD 4.x and 5.x does not properly handle certain Linux system calls, which could allow local users to access kernel memory to gain privileges or cause a system panic.
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Analysis
by VulDB Data Team • 06/28/2019
The vulnerability identified as CVE-2004-0602 resides within FreeBSD's binary compatibility layer designed to support Linux applications running on FreeBSD systems. This flaw specifically affects FreeBSD versions 4.x and 5.x where the operating system implements a compatibility mode to execute Linux binaries through a translation layer that maps Linux system calls to their FreeBSD equivalents. The technical implementation of this compatibility mode contains a critical flaw in how it processes certain Linux system calls, creating a pathway for malicious exploitation. When these particular system calls are invoked through the compatibility layer, the kernel fails to properly validate or sanitize the parameters, leading to improper memory handling within the kernel space.
The operational impact of this vulnerability extends beyond simple privilege escalation to include potential system instability through kernel memory access violations. Local attackers who can execute code within the compatibility environment can leverage this flaw to read kernel memory contents, potentially extracting sensitive information such as cryptographic keys, passwords, or other confidential data stored in kernel memory. Additionally, the vulnerability can be exploited to trigger kernel panics, resulting in denial of service conditions that can bring entire systems down. This represents a significant security risk as it allows local users to bypass traditional security boundaries that separate user space from kernel space, effectively undermining the fundamental security model of the operating system.
The vulnerability aligns with CWE-125, which describes "Out-of-bounds Read" conditions, and CWE-200, which covers "Information Exposure", as the flaw enables unauthorized access to kernel memory regions that should remain protected. From an ATT&CK framework perspective, this vulnerability maps to T1068, "Exploitation for Privilege Escalation", and T1499, "Endpoint Denial of Service", as it can be used to escalate privileges and cause system instability. The attack surface is particularly concerning because it requires no special privileges to exploit initially, as local users can trigger the vulnerability through normal application execution within the compatibility layer. The exploitation process typically involves crafting specific Linux system calls that, when processed through FreeBSD's compatibility mode, cause the kernel to access memory locations without proper bounds checking. This type of vulnerability demonstrates the inherent complexity and risk associated with system call translation layers, where the translation process itself becomes a potential attack vector rather than merely a compatibility facilitator. Organizations running FreeBSD 4.x or 5.x systems should immediately implement mitigations including system updates to patched versions, disabling unnecessary binary compatibility modes, or implementing additional access controls to limit local user privileges within the compatibility environment.
This vulnerability highlights the critical importance of proper memory management and input validation in kernel space operations. The flaw represents a classic case of inadequate bounds checking within the compatibility layer, where the translation of system calls from one operating system to another creates unexpected security implications. The design of such compatibility layers must account for the security implications of translating between different kernel interfaces, as the translation process itself can introduce new attack vectors that were not present in the original system implementations.