CVE-2005-1913 in Linux
Summary
by MITRE
The Linux kernel 2.6 before 2.6.12.1 allows local users to cause a denial of service (kernel panic) via a non group-leader thread executing a different program than was pending in itimer, which causes the signal to be delivered to the old group-leader task, which does not exist.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/02/2019
The vulnerability described in CVE-2005-1913 represents a critical race condition within the Linux kernel's signal handling mechanism that specifically affects kernel versions prior to 2.6.12.1. This flaw exists in the interaction between the itimer subsystem and process group management, creating a scenario where a malicious local user can trigger a kernel panic through carefully orchestrated timing attacks. The vulnerability manifests when a non-group-leader thread attempts to execute a different program while an itimer signal is pending, leading to a cascading failure in the kernel's signal delivery logic.
The technical root cause of this vulnerability lies in the improper handling of signal delivery when process group leadership changes during the execution of system calls. When a thread that is not the group leader executes a different program while an itimer signal is pending, the kernel attempts to deliver that signal to what it believes to be the original group-leader task. However, since the process group has already changed through the execution of a new program, this original group-leader task no longer exists, causing the kernel to attempt operations on a non-existent process structure. This results in a kernel panic as the kernel's signal handling code cannot properly manage the reference to a destroyed process group leader, creating an unhandled exception in kernel space.
The operational impact of this vulnerability is severe as it allows any local user with access to the system to cause a complete system crash through a denial of service attack. The vulnerability does not require special privileges beyond normal user access and can be exploited by a malicious user to repeatedly crash the system, leading to availability disruption that can affect critical services. The timing aspect of this vulnerability makes it particularly challenging to prevent since it relies on specific conditions that may occur during normal system operation, making it difficult to detect and mitigate through traditional monitoring approaches. This vulnerability directly maps to CWE-362, which describes a race condition in concurrent execution contexts, and aligns with ATT&CK technique T1499.004 for network denial of service through system resource exhaustion.
The mitigation strategy for this vulnerability involves upgrading to Linux kernel version 2.6.12.1 or later, where the kernel developers implemented proper checks to prevent the delivery of signals to non-existent process group leaders. System administrators should also implement proper patch management procedures to ensure all systems are running patched kernel versions. Additionally, monitoring for unusual kernel panic patterns or repeated system crashes may help detect exploitation attempts, though the timing nature of the vulnerability makes detection challenging. Organizations should also consider implementing process isolation measures and monitoring for abnormal process group transitions to reduce the attack surface for this particular vulnerability.