CVE-2002-0132 in Chinput
Summary
by MITRE
Buffer overflow in Chinput 3.0 allows local users to execute arbitrary code via a long HOME environment variable.
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Analysis
by VulDB Data Team • 11/17/2024
The vulnerability identified as CVE-2002-0132 represents a classic buffer overflow flaw within the Chinput 3.0 input handling system that affects Unix-like operating environments. This issue specifically targets the management of the HOME environment variable, which serves as a critical system parameter indicating the user's home directory location. The vulnerability exists in the way Chinput processes and stores environment variables, particularly when the HOME variable exceeds the allocated buffer space. When a local user manipulates the HOME environment variable to exceed the predetermined buffer limits, the program fails to properly validate input length, leading to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected process.
The technical implementation of this vulnerability stems from improper bounds checking within the Chinput application's environment variable handling routines. The buffer overflow occurs during the processing of the HOME environment variable, where the application assumes a maximum length for this variable without implementing adequate input validation or boundary checks. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios. The vulnerability demonstrates a fundamental lack of secure coding practices in memory management and input validation, where the application fails to enforce proper buffer size limits when copying environment variable data into internal storage structures.
From an operational perspective, this vulnerability presents a significant security risk as it allows local users to escalate privileges and execute malicious code on systems running Chinput 3.0. The local execution requirement means that attackers must already have access to the target system to exploit this vulnerability, but once achieved, the consequences can be severe as the malicious code executes with the privileges of the Chinput process. The attack vector is particularly concerning because environment variables are commonly manipulated by users during system interactions, making this vulnerability accessible through routine system usage patterns. The exploitation typically involves crafting a specially crafted HOME environment variable that, when processed by Chinput, overflows the allocated buffer and overwrites adjacent memory locations, potentially including return addresses or function pointers that can be redirected to execute attacker-controlled code.
The impact of this vulnerability extends beyond immediate code execution capabilities as it represents a foundational security weakness that can serve as a foothold for more sophisticated attacks. Security professionals should note that this vulnerability demonstrates the importance of input validation and proper buffer management in system applications. Organizations should prioritize patching affected systems and implementing proper environment variable sanitization practices. The ATT&CK framework categorizes this type of vulnerability under T1068, which describes 'Exploitation for Privilege Escalation,' where local users leverage system weaknesses to gain elevated privileges. Mitigation strategies include applying vendor patches, implementing environment variable length restrictions, and conducting regular security assessments to identify similar buffer overflow vulnerabilities in other system components. Additionally, system administrators should consider implementing monitoring solutions that can detect anomalous environment variable usage patterns that might indicate exploitation attempts, as well as establishing robust input validation mechanisms across all applications that process user-supplied data.