CVE-2007-0997 in Linux
Summary
by MITRE
Race condition in the tee (sys_tee) system call in the Linux kernel 2.6.17 through 2.6.17.6 might allow local users to cause a denial of service (system crash), obtain sensitive information (kernel memory contents), or gain privileges via unspecified vectors related to a potentially dropped ipipe lock during a race between two pipe readers.
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Analysis
by VulDB Data Team • 04/13/2019
The vulnerability described in CVE-2007-0997 represents a critical race condition affecting the Linux kernel's tee system call implementation within versions 2.6.17 through 2.6.17.6. This flaw exists within the kernel's pipe subsystem where the sys_tee system call facilitates data transfer between pipe file descriptors. The race condition manifests when multiple processes attempt to read from the same pipe simultaneously, creating a timing window that exposes the kernel to unpredictable behavior. The vulnerability operates at the kernel level and directly impacts the integrity of the kernel's internal locking mechanisms, specifically involving the ipipe lock which serves as a critical synchronization primitive for maintaining data consistency across concurrent operations.
The technical implementation of this vulnerability stems from improper handling of the ipipe lock during concurrent pipe read operations. When two or more processes attempt to read from the same pipe in rapid succession, the kernel's locking mechanism fails to properly serialize access, leading to a scenario where the ipipe lock may be dropped or improperly released during the race window. This condition creates opportunities for memory corruption and unpredictable kernel behavior that can result in system crashes, information disclosure, or privilege escalation. The vulnerability's root cause aligns with CWE-362, which specifically addresses race conditions in concurrent programming, and represents a classic example of improper locking or synchronization in kernel space operations. The flaw is particularly concerning because it operates at the kernel level where any memory corruption or lock manipulation can lead to complete system compromise.
The operational impact of CVE-2007-0997 extends beyond simple denial of service scenarios to encompass potential privilege escalation and information disclosure threats. Local attackers can exploit this vulnerability to cause system crashes that result in denial of service, but more critically, the race condition may allow them to read kernel memory contents that could reveal sensitive information such as credentials, encryption keys, or other confidential data. The privilege escalation aspect occurs when the improper lock handling allows malicious processes to manipulate kernel data structures in ways that could elevate their privileges to root level. This vulnerability directly maps to several ATT&CK techniques including privilege escalation through kernel exploits and defense evasion via system crash generation. The attack surface is particularly wide because any process with access to pipe operations can potentially trigger the race condition, making it a significant concern for systems where local users have access to process execution capabilities.
Mitigation strategies for this vulnerability require immediate kernel version upgrades to patched releases that address the race condition in the tee system call implementation. System administrators should prioritize updating to kernel versions 2.6.17.7 or later where the race condition has been resolved through proper synchronization mechanisms and lock handling. Additional defensive measures include implementing proper access controls to limit local user privileges and monitoring for unusual pipe operations that might indicate exploitation attempts. The vulnerability demonstrates the importance of rigorous kernel testing for concurrent programming issues and highlights the necessity of proper lock management in kernel space operations. Organizations should also consider implementing kernel hardening techniques such as stack canaries, kernel address space layout randomization, and other security mitigations that can reduce the effectiveness of potential exploitation attempts even if the underlying vulnerability remains unpatched.