CVE-2001-0317 in Linux
Summary
by MITRE
Race condition in ptrace in Linux kernel 2.4 and 2.2 allows local users to gain privileges by using ptrace to track and modify a running setuid process.
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Analysis
by VulDB Data Team • 10/20/2024
The vulnerability described in CVE-2001-0317 represents a critical race condition within the Linux kernel's ptrace system call implementation affecting versions 2.2 and 2.4. This flaw exploits the timing window between when a process is attached to another process using ptrace and when the attached process begins executing, creating an opportunity for privilege escalation. The race condition occurs specifically when a local user attempts to trace a running setuid process, which typically executes with elevated privileges due to its special permissions. The fundamental issue lies in the kernel's failure to properly synchronize access to process memory and execution states during the ptrace attachment sequence.
The technical implementation of this vulnerability stems from the kernel's insufficient locking mechanisms when handling ptrace operations on setuid processes. When a user process calls ptrace to attach to a setuid process, the kernel must validate permissions and potentially modify the target process's execution state. However, the race condition allows an attacker to manipulate the process state between the initial attachment request and the actual execution of the target process. This timing gap enables the attacker to modify the target process's memory or execution flow before the kernel can properly enforce security checks. The vulnerability is particularly dangerous because it leverages the legitimate ptrace functionality while exploiting implementation flaws in the kernel's privilege management system.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and unauthorized access to sensitive data. Local attackers who can execute processes on the target system can exploit this flaw to gain root privileges, effectively bypassing the security model that protects setuid binaries. Once escalated, attackers can manipulate system files, install backdoors, or access confidential information stored in processes running with elevated permissions. The vulnerability affects all systems running Linux kernel versions 2.2 and 2.4 where ptrace is enabled, making it particularly widespread across the Linux ecosystem during that time period. This flaw directly violates security principles established in the Common Weakness Enumeration framework, specifically mapping to CWE-362, which describes race conditions that can lead to privilege escalation.
Mitigation strategies for this vulnerability require immediate kernel updates to patched versions that address the synchronization issues in ptrace implementation. System administrators should prioritize applying security patches from their Linux distribution vendors to prevent exploitation. Additional protective measures include restricting ptrace capabilities through system configuration options and implementing monitoring for unusual ptrace activity patterns. The vulnerability highlights the importance of proper kernel locking mechanisms and the need for careful consideration of security implications when implementing system call interfaces. Organizations should also consider implementing process monitoring and privilege auditing to detect potential exploitation attempts, aligning with defensive techniques outlined in the MITRE ATT&CK framework under privilege escalation tactics. The fix typically involves implementing proper mutex locking or atomic operations during the ptrace attachment sequence to ensure that process state modifications occur atomically and that security checks are properly enforced before any execution state changes take effect.