CVE-2009-0343 in Systrace
Summary
by MITRE
Niels Provos Systrace 1.6f and earlier on the x86_64 Linux platform allows local users to bypass intended access restrictions by making a 32-bit syscall with a syscall number that corresponds to a policy-compliant 64-bit syscall, related to race conditions that occur in monitoring 64-bit processes.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability described in CVE-2009-0343 affects Systrace version 1.6f and earlier implementations on x86_64 Linux systems, representing a critical security flaw in system call monitoring mechanisms. This issue specifically targets the way Systrace handles syscall number validation when processing 32-bit system calls on 64-bit architectures, creating a pathway for local attackers to circumvent access controls that were designed to protect system resources and maintain security boundaries.
The technical flaw stems from a race condition that occurs during the monitoring of 64-bit processes, where Systrace fails to properly validate syscall numbers when transitioning between 32-bit and 64-bit syscall interfaces. When a local user executes a 32-bit system call with a syscall number that maps to a legitimate 64-bit syscall that is permitted by the current policy, the monitoring system incorrectly grants access to the restricted operation. This behavior exploits the inherent differences in syscall number spaces between 32-bit and 64-bit architectures, where certain syscall numbers exist in both domains but represent different operations.
The operational impact of this vulnerability is significant as it allows local users to bypass intended access restrictions without requiring elevated privileges or complex exploitation techniques. Attackers can leverage this weakness to execute system calls that should normally be blocked by Systrace policies, potentially leading to privilege escalation, information disclosure, or system compromise. The vulnerability is particularly dangerous because it operates at the kernel level and can be exploited by any user with local access to the system, making it a persistent threat in multi-user environments.
This vulnerability aligns with CWE-362, which describes race conditions that can lead to security flaws, and demonstrates characteristics consistent with ATT&CK technique T1068, which involves exploiting local privileges to gain elevated access. The flaw represents a classic case of improper input validation in security-critical system components, where the architecture-specific differences between 32-bit and 64-bit syscall interfaces create an unexpected bypass mechanism. Organizations should implement immediate mitigations including updating to patched versions of Systrace, reviewing and strengthening system call policies, and considering alternative security monitoring approaches that properly handle architecture-specific syscall number mappings. The vulnerability highlights the importance of thorough testing across different architectural platforms when implementing security controls and demonstrates how seemingly benign architectural differences can create significant security implications.