CVE-2005-1762 in Linux
Summary
by MITRE
The ptrace call in the Linux kernel 2.6.8.1 and 2.6.10 for the AMD64 platform allows local users to cause a denial of service (kernel crash) via a "non-canonical" address.
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Analysis
by VulDB Data Team • 06/11/2019
The vulnerability identified as CVE-2005-1762 represents a critical flaw in the Linux kernel's ptrace system call implementation specifically affecting AMD64 platforms running kernel versions 2.6.8.1 and 2.6.10. This issue stems from inadequate validation of memory addresses within the ptrace functionality, creating a condition where malicious local users can exploit the kernel's handling of non-canonical addresses to trigger system crashes. The ptrace system call serves as a fundamental debugging mechanism allowing processes to observe and control the execution of other processes, making it a critical component in system security and debugging operations. When a process attempts to use ptrace with malformed memory addresses, particularly those that do not conform to the canonical address format required by AMD64 architecture, the kernel fails to properly handle these invalid inputs leading to immediate system termination.
The technical root cause of this vulnerability lies in the kernel's memory management subsystem's failure to validate address formats during ptrace operations. In AMD64 architecture, memory addresses must follow specific canonical forms to ensure proper memory access and prevent certain types of memory corruption. A non-canonical address violates these architectural requirements and represents an invalid memory reference that the kernel should reject rather than attempt to process. This flaw falls under CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write vulnerabilities. The ptrace implementation does not properly check whether the address parameter conforms to the canonical address format, allowing attackers to pass malformed addresses that cause the kernel to attempt operations on invalid memory locations, ultimately leading to kernel panic and system crash.
From an operational perspective, this vulnerability poses significant risks to system availability and stability. Local users with minimal privileges can exploit this flaw to cause denial of service conditions affecting the entire system, potentially disrupting critical services and applications running on the affected kernel. The impact extends beyond simple system crashes as it can be leveraged to disrupt system operations, cause data loss, and potentially provide a foothold for further attacks. The vulnerability is particularly concerning because it requires only local access to exploit, meaning any user with login privileges on the system can potentially trigger the crash. This makes it a high-risk vulnerability in multi-user environments where privilege escalation might be possible through other means, as the initial crash can be used as a stepping stone for more sophisticated attacks. The attack pattern aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, as local users can leverage this vulnerability to execute disruptive operations.
The mitigation strategy for CVE-2005-1762 primarily involves upgrading to patched kernel versions where the ptrace implementation properly validates address formats and rejects non-canonical addresses before attempting any kernel operations. System administrators should prioritize applying security patches from their respective kernel vendors, as the vulnerability affects specific kernel versions and is not present in patched releases. Additionally, implementing proper access controls and privilege management can help limit the potential impact by restricting local user access to systems where this vulnerability exists. Monitoring for unusual ptrace system call usage patterns and implementing intrusion detection systems can help identify exploitation attempts. Organizations should also consider implementing kernel hardening measures such as kernel address space layout randomization and other security enhancements that can make exploitation more difficult. The vulnerability highlights the importance of proper input validation in kernel space operations and serves as a reminder of the critical need for thorough testing of system call implementations, particularly those that operate with elevated privileges and have direct access to system memory management functions.