CVE-2009-0834 in Linux
Summary
by MITRE
The audit_syscall_entry function in the Linux kernel 2.6.28.7 and earlier on the x86_64 platform does not properly handle (1) a 32-bit process making a 64-bit syscall or (2) a 64-bit process making a 32-bit syscall, which allows local users to bypass certain syscall audit configurations via crafted syscalls, a related issue to CVE-2009-0342 and CVE-2009-0343.
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Analysis
by VulDB Data Team • 08/30/2019
The vulnerability described in CVE-2009-0834 resides within the Linux kernel's audit subsystem, specifically in the audit_syscall_entry function that governs how system calls are recorded and monitored for security purposes. This flaw affects kernel versions 2.6.28.7 and earlier, particularly on x86_64 architecture platforms where the complexity of handling mixed-mode system calls creates a critical gap in audit functionality. The issue stems from inadequate handling of syscall transitions between 32-bit and 64-bit process environments, creating a scenario where audit configurations can be circumvented through carefully crafted syscall sequences.
The technical flaw manifests when a 32-bit process executes a 64-bit system call or when a 64-bit process makes a 32-bit system call, both of which require special handling within the kernel's audit framework. During these mixed-mode transitions, the audit_syscall_entry function fails to properly validate or process the syscall entry points, allowing malicious processes to exploit this inconsistency in audit handling. This vulnerability operates at the kernel level and specifically targets the audit subsystem's ability to track and log system calls accurately, creating a pathway for bypassing security controls that rely on syscall auditing.
The operational impact of this vulnerability is significant for system security, as it allows local users to evade audit controls that are meant to monitor critical system activities. When a process can bypass syscall audit configurations, it undermines the integrity of security monitoring systems that depend on comprehensive syscall logging for threat detection and compliance enforcement. This weakness enables attackers to perform malicious activities without leaving proper audit trails, making incident response and forensic analysis substantially more difficult. The vulnerability particularly affects systems that rely on syscall auditing for security monitoring, potentially allowing privilege escalation or other malicious activities to remain undetected.
Mitigation strategies for CVE-2009-0834 focus primarily on kernel updates to versions that address the audit handling inconsistencies in mixed-mode syscall environments. System administrators should prioritize applying security patches that correct the audit_syscall_entry function's handling of 32-bit to 64-bit and 64-bit to 32-bit syscall transitions. Additionally, organizations can implement supplementary monitoring measures to detect anomalous syscall patterns that might indicate exploitation attempts, though these are not comprehensive solutions. The vulnerability aligns with CWE-284 access control weaknesses and can be categorized under ATT&CK technique T1059 for system call manipulation, making it a critical target for kernel security hardening efforts. Organizations should also consider implementing additional security controls beyond syscall auditing to compensate for potential audit bypass scenarios while awaiting full patch deployment.