CVE-2005-0666 in Pax Linux
Summary
by MITRE
Unknown vulnerability in PaX from the September 2003 release to 2.2 before 2005.03.05, related to SEGMEXEC or RANDEXEC and VMA mirroring, allows local users and possibly remote attackers to bypass intended access restrictions and execute arbitrary code.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2005-0666 represents a critical security flaw within the PaX security framework, a widely adopted Linux kernel patch set designed to provide advanced memory protection mechanisms. This vulnerability existed within PaX versions from the September 2003 release through version 2.2, specifically persisting until the 2005.03.05 release. The flaw is particularly concerning as it affects core memory management protections that are fundamental to modern operating system security architectures, creating a potential backdoor for both local and remote attackers to circumvent critical access controls.
The technical nature of this vulnerability is rooted in the improper implementation of SEGMEXEC and RANDEXEC memory protection features combined with Virtual Memory Area (VMA) mirroring mechanisms. These features are designed to prevent code execution in data segments and randomize memory layout to thwart exploitation techniques such as buffer overflow attacks. The flaw occurs when the kernel fails to properly validate memory access permissions during VMA operations, allowing malicious code to manipulate memory mappings in ways that violate intended security boundaries. This issue specifically relates to how the kernel handles memory protection flags and access control lists during memory allocation and mapping operations, creating a window where unauthorized code execution can occur.
From an operational perspective, this vulnerability presents a severe risk to systems running affected PaX versions as it essentially undermines the fundamental security model that the framework was designed to enforce. Local users can exploit this flaw to escalate privileges and execute arbitrary code with elevated permissions, while remote attackers may potentially leverage this weakness in network services running on vulnerable systems. The impact extends beyond simple privilege escalation as the vulnerability can be used to bypass other security controls such as stack canaries, address space layout randomization, and other exploit mitigations that are standard in modern secure computing environments. This weakness essentially creates a persistent backdoor that can be exploited repeatedly without detection, making it particularly dangerous for long-running systems.
The vulnerability's classification aligns with CWE-284, which addresses improper access control in software systems, and it intersects with multiple ATT&CK techniques including privilege escalation and defense evasion. Organizations using PaX must implement immediate mitigations including updating to the patched version 2005.03.05 or later, applying kernel security patches, and conducting comprehensive security audits of systems running vulnerable versions. Additionally, system administrators should consider implementing additional monitoring controls to detect potential exploitation attempts, as this vulnerability can be used to establish persistent access to compromised systems. The remediation process requires careful consideration of system compatibility and testing to ensure that the updated security patches do not introduce regressions in system functionality while effectively closing this critical access control bypass vulnerability.