CVE-2005-3783 in Linux
Summary
by MITRE
The ptrace functionality (ptrace.c) in Linux kernel 2.6 before 2.6.14.2, using CLONE_THREAD, does not use the thread group ID to check whether it is attaching to itself, which allows local users to cause a denial of service (crash).
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Analysis
by VulDB Data Team • 06/12/2019
The vulnerability described in CVE-2005-3783 represents a critical flaw in the Linux kernel's ptrace implementation that existed in versions prior to 2.6.14.2. This issue specifically affects the ptrace system call functionality which is designed to allow one process to observe and control the execution of another process, commonly used for debugging and process monitoring. The vulnerability stems from the improper handling of thread group identification when processes attempt to attach to themselves using the CLONE_THREAD flag, which creates a new thread within the same thread group. This flaw enables local attackers to exploit the kernel's insufficient validation mechanisms to trigger system crashes.
The technical root cause of this vulnerability lies in the kernel's ptrace.c implementation where the system fails to properly utilize thread group IDs when validating ptrace operations. When a process attempts to attach to itself using CLONE_THREAD, the kernel should verify that the operation is legitimate by checking the thread group ID to prevent self-attachment scenarios. However, the vulnerable implementation bypasses this critical validation step, allowing malicious processes to perform ptrace operations that should be prohibited. This oversight creates a condition where the kernel's internal state becomes inconsistent, leading to memory corruption and ultimately system crashes.
The operational impact of this vulnerability is significant as it enables local users to execute a denial of service attack against the target system. An attacker with local access can exploit this flaw to cause kernel panics or system crashes, effectively rendering the affected system unusable until manual reboot occurs. This type of vulnerability is particularly dangerous in multi-user environments or systems where local access is not strictly controlled, as it allows any user to potentially disrupt system services and compromise system availability. The vulnerability affects all processes running on Linux systems with kernel versions prior to 2.6.14.2, making it a widespread concern for system administrators and security professionals.
The vulnerability aligns with CWE-119 which describes improper restriction of operations within a limited context, specifically manifesting as an issue with insufficient validation of process attachment operations. From an attack framework perspective, this vulnerability could be categorized under ATT&CK technique T1059 for system compromise through kernel-level exploitation, and potentially T1499 for availability disruption through system crash. The flaw demonstrates the importance of proper kernel-level validation and the potential consequences of inadequate access control mechanisms in privileged system components. System administrators should immediately apply the kernel patch released with version 2.6.14.2 to mitigate this vulnerability and prevent exploitation by local attackers. The fix involves implementing proper thread group ID checking during ptrace operations to prevent unauthorized self-attachment scenarios that could lead to system instability.