CVE-2008-2944 in Enterprise Linux Kernel
Summary
by MITRE
Double free vulnerability in the utrace support in the Linux kernel, probably 2.6.18, in Red Hat Enterprise Linux (RHEL) 5 and Fedora Core 6 (FC6) allows local users to cause a denial of service (oops), as demonstrated by a crash when running the GNU GDB testsuite, a different vulnerability than CVE-2008-2365.
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Analysis
by VulDB Data Team • 11/14/2017
The CVE-2008-2944 vulnerability represents a critical double free condition within the Linux kernel's utrace support functionality, specifically affecting kernel versions around 2.6.18 in Red Hat Enterprise Linux 5 and Fedora Core 6 distributions. This flaw resides in the kernel's debugging and tracing subsystem, where the utrace mechanism handles user-space tracing operations. The vulnerability manifests when kernel code improperly manages memory allocation and deallocation sequences, leading to the same memory block being freed twice during the execution of tracing operations. Such double free conditions are particularly dangerous because they can result in memory corruption that may be exploited to escalate privileges or cause system instability.
The technical implementation of this vulnerability involves the kernel's utrace subsystem where specific tracing operations fail to properly validate memory management sequences. When a local user executes malicious code or triggers specific kernel tracing operations, the kernel's memory allocator receives duplicate free requests for the same memory region. This particular flaw demonstrates how kernel-level memory management can be compromised through seemingly innocuous tracing operations, making it particularly insidious for system administrators who may not immediately recognize the impact of tracing functionality on system stability. The vulnerability operates at the kernel level, making it difficult to detect through standard user-space security measures and requiring deep understanding of kernel internals to properly analyze.
The operational impact of CVE-2008-2944 extends beyond simple denial of service conditions, as the kernel oops (kernel panic) that occurs can lead to complete system crashes and potential data loss. The vulnerability was demonstrated through the GNU GDB testsuite, indicating that legitimate debugging tools could trigger the condition, making it particularly concerning for development environments and production systems where debugging capabilities are essential. This vulnerability affects systems running kernel versions prior to the patch release that addressed the double free condition, and represents a classic example of how kernel-level memory corruption can be exploited to cause system instability. The flaw's classification aligns with CWE-415, which describes double free conditions in software, and could potentially be leveraged in conjunction with other kernel vulnerabilities to achieve privilege escalation as outlined in various ATT&CK framework techniques for kernel exploitation.
Mitigation strategies for this vulnerability require immediate kernel updates to versions that contain the patched utrace implementation, as the flaw cannot be effectively addressed through configuration changes or user-space workarounds. System administrators should prioritize patching affected systems, particularly those running older kernel versions where the vulnerability exists, and implement monitoring for kernel oops conditions that may indicate exploitation attempts. The vulnerability's nature as a kernel-level memory management issue means that traditional security controls like firewalls or intrusion detection systems provide no protection, requiring direct kernel-level remediation through vendor patches or custom kernel modifications. Organizations should also consider implementing kernel hardening measures such as stack canaries, kernel address space layout randomization, and other defenses that can help prevent exploitation attempts while awaiting proper patches. The vulnerability highlights the critical importance of maintaining up-to-date kernel versions and the need for comprehensive security testing of kernel subsystems, particularly those involving debugging and tracing functionality that may be exposed to untrusted users.