CVE-2002-1687 in AIX
Summary
by MITRE
Buffer overflow in the diagnostics library in AIX allows local users to "cause data and instructions to be overwritten" via a long DIAGNOSTICS environment variable.
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Analysis
by VulDB Data Team • 09/02/2019
The vulnerability described in CVE-2002-1687 represents a critical buffer overflow flaw within the diagnostics library component of IBM AIX operating systems. This issue manifests when the system processes a DIAGNOSTICS environment variable that exceeds the allocated buffer size, creating an exploitable condition that can be leveraged by local attackers. The flaw exists in the way the system handles environment variable input validation, specifically within the diagnostic subsystem that manages system health checks and troubleshooting functions. The buffer overflow occurs during the parsing and processing of diagnostic environment variables, where insufficient bounds checking allows malicious input to overwrite adjacent memory regions.
The technical implementation of this vulnerability aligns with CWE-121, which categorizes buffer overflow conditions where insufficient boundary checking allows attackers to write data beyond the allocated buffer space. This particular implementation affects the AIX operating system's diagnostic library, which is responsible for processing system diagnostic information and environmental variables. When a local user sets a DIAGNOSTICS environment variable containing excessive data, the system fails to properly validate the input length against the predetermined buffer limits. The overflow can potentially overwrite critical data structures, function return addresses, and even executable instructions, providing attackers with opportunities to execute arbitrary code with the privileges of the affected process. The vulnerability is classified as a local privilege escalation vector since it requires local system access but can potentially elevate privileges to root level depending on the process context.
The operational impact of CVE-2002-1687 extends beyond simple system instability, as it creates a potential pathway for persistent system compromise. Attackers can leverage this vulnerability to overwrite critical system memory segments, potentially leading to system crashes, data corruption, or complete system takeover. The attack surface is particularly concerning because it operates at the system level where diagnostic functions typically run with elevated privileges. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and execution of malicious code within system processes. The vulnerability affects systems running various AIX versions where the diagnostic library fails to implement proper input validation mechanisms. The exploitability is enhanced by the fact that environment variables are commonly used in system configuration and can be easily manipulated by local users without requiring network access.
Mitigation strategies for CVE-2002-1687 should focus on both immediate defensive measures and long-term system hardening. System administrators should implement strict input validation for environment variables, particularly those related to diagnostic functions, and ensure that all AIX systems are updated with the latest security patches from IBM. The implementation of stack protection mechanisms and address space layout randomization can help reduce exploit reliability. Additionally, monitoring for unusual environment variable usage patterns and implementing process isolation for diagnostic functions can provide early detection capabilities. Organizations should also consider restricting local user access to system diagnostic functions where possible, as the vulnerability requires local system access to exploit. The vulnerability highlights the importance of proper input validation and buffer management in system-level libraries, emphasizing that even diagnostic components must adhere to secure coding practices to prevent exploitation. Regular security assessments and code reviews focusing on buffer handling in system libraries should be implemented to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.