CVE-2005-2553 in Linux
Summary
by MITRE
The find_target function in ptrace32.c in the Linux kernel 2.4.x before 2.4.29 does not properly handle a NULL return value from another function, which allows local users to cause a denial of service (kernel crash/oops) by running a 32-bit ltrace program with the -i option on a 64-bit executable program.
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Analysis
by VulDB Data Team • 06/11/2019
The vulnerability described in CVE-2005-2553 represents a critical kernel-level flaw in the Linux 2.4.x series that specifically affects systems running 64-bit architectures. This issue resides within the ptrace32.c file, which handles ptrace operations for 32-bit applications running on 64-bit kernels through compatibility layer mechanisms. The vulnerability manifests when a local user executes a 32-bit ltrace program with the -i option against a 64-bit executable, triggering a kernel crash or oops condition that effectively causes a denial of service.
The technical root cause of this vulnerability stems from improper error handling within the find_target function, which fails to adequately check for NULL return values from underlying functions it calls. This particular flaw falls under the category of improper error handling as defined by CWE-252, where the system does not properly validate or handle error conditions that occur during function execution. The ptrace subsystem in Linux is designed to allow one process to observe and control the execution of another process, commonly used for debugging and tracing operations. When ltrace attempts to trace a 64-bit executable, it utilizes the ptrace32 compatibility layer to interface with the kernel, but the absence of proper NULL pointer validation creates an exploitable condition.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged by local attackers to destabilize system operations through kernel crashes. The vulnerability specifically affects systems running Linux kernel versions 2.4.x prior to 2.4.29, making it particularly relevant to older systems that may still be in operation within certain enterprise environments or embedded systems. When exploited, the vulnerability causes the kernel to crash with an oops message, which represents a kernel-level error condition that typically results in system instability and requires manual reboot to restore normal operation. This type of local privilege escalation vector can be particularly dangerous in multi-user environments where an unprivileged user could potentially disrupt system services.
The exploitation of this vulnerability aligns with techniques described in the ATT&CK framework under the T1068 - Exploitation for Privilege Escalation tactic, as local users can leverage kernel-level flaws to achieve system compromise. The specific attack vector involves the use of ltrace, a program that traces library calls and system calls, combined with the -i option that enables instruction-level tracing. This combination triggers the problematic code path in the ptrace32.c file where the NULL return value handling fails, leading to the kernel crash. The vulnerability demonstrates the importance of proper error handling in kernel space, where the failure to validate return values from function calls can result in catastrophic system failures. System administrators and security professionals should prioritize patching affected systems to address this vulnerability, as it represents a straightforward denial of service attack that can be executed by any local user with basic system access.
Mitigation strategies for this vulnerability primarily involve applying the appropriate kernel security patches released by the Linux kernel development team. The fix implemented in kernel version 2.4.29 and later addresses the specific NULL pointer handling issue within the find_target function, ensuring that proper validation occurs before attempting to use return values from function calls. Organizations should also consider implementing additional security measures such as restricting local user access to debugging tools like ltrace, monitoring for unusual kernel crash patterns, and maintaining up-to-date kernel versions to prevent exploitation of known vulnerabilities. The vulnerability underscores the critical importance of thorough testing and validation of error handling mechanisms in kernel code, particularly in compatibility layers that bridge different architectural environments.