CVE-2008-5079 in Linux
Summary
by MITRE
net/atm/svc.c in the ATM subsystem in the Linux kernel 2.6.27.8 and earlier allows local users to cause a denial of service (kernel infinite loop) by making two calls to svc_listen for the same socket, and then reading a /proc/net/atm/*vc file, related to corruption of the vcc table.
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Analysis
by VulDB Data Team • 12/22/2024
The vulnerability described in CVE-2008-5079 resides within the ATM (Asynchronous Transfer Mode) subsystem of the Linux kernel, specifically in the net/atm/svc.c file. This flaw affects kernel versions up to and including 2.6.27.8, representing a critical security issue that can be exploited locally to cause system-wide denial of service. The vulnerability manifests through improper handling of socket operations within the ATM networking framework, creating a condition where the kernel enters an infinite loop during processing of certain network operations. The issue is particularly concerning because it operates at the kernel level, meaning that a local attacker with minimal privileges can potentially disrupt system operations and render the machine unstable or unresponsive.
The technical root cause of this vulnerability stems from a flaw in how the ATM subsystem manages Virtual Channel Connections (VCC) when processing svc_listen calls. When a local user makes two consecutive calls to svc_listen for the same socket and subsequently reads from the /proc/net/atm/*vc file, the vcc table becomes corrupted. This corruption leads to a condition where the kernel's processing logic enters an infinite loop, continuously cycling through the corrupted data structures without proper termination conditions. The vcc table corruption occurs due to inadequate validation and handling of duplicate socket operations, allowing the system to maintain inconsistent state information that triggers the problematic loop behavior. This flaw directly relates to CWE-835, which describes infinite loops or iterations without proper exit conditions, and demonstrates how improper state management can lead to system instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it can effectively render the entire system unusable until the kernel is restarted or the affected processes are terminated. Local users can exploit this weakness without requiring elevated privileges, making it particularly dangerous in multi-user environments where system stability is paramount. The infinite loop consumes system resources continuously, potentially leading to complete system lockup or resource exhaustion that affects other critical services. This vulnerability also has implications for system availability and reliability, as the kernel's inability to properly handle the corrupted vcc table prevents normal network operations from functioning correctly. The attack vector is straightforward and can be executed repeatedly, making it a persistent threat to system uptime and operational continuity.
Mitigation strategies for CVE-2008-5079 should focus on both immediate patching and system hardening measures. The primary recommendation is to upgrade to a kernel version that contains the appropriate fix, which was implemented in kernel versions 2.6.28 and later. System administrators should also implement monitoring solutions to detect unusual patterns in kernel resource consumption that might indicate the presence of this vulnerability. Additionally, access controls should be enforced to limit local user privileges where possible, reducing the attack surface for this type of exploitation. The vulnerability's characteristics align with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a classic example of how kernel-level flaws can be exploited to cause system-wide disruptions. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates, particularly for critical kernel vulnerabilities that can be exploited locally to cause system instability and denial of service conditions.