CVE-2001-0533 in AIX
Summary
by MITRE
Buffer overflow in libi18n library in IBM AIX 5.1 and 4.3.x allows local users to gain root privileges via a long LANG environmental variable.
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Analysis
by VulDB Data Team • 01/14/2018
The vulnerability identified as CVE-2001-0533 represents a critical buffer overflow flaw within the libi18n library of IBM AIX operating systems version 5.1 and 4.3.x series. This issue resides in the internationalization library that handles locale and language settings, specifically when processing the LANG environment variable. The flaw enables local attackers with basic user privileges to execute arbitrary code with elevated root permissions through a carefully crafted environmental variable input.
The technical implementation of this vulnerability stems from improper bounds checking within the libi18n library's handling of the LANG environment variable. When a user sets an excessively long LANG value, the library fails to validate the input length before copying it into a fixed-size buffer. This classic buffer overflow condition occurs because the library uses unsafe string handling functions that do not perform adequate length verification before memory operations. The vulnerability is particularly dangerous because it operates within a system library that is frequently accessed during normal system operations, making exploitation both feasible and persistent. The flaw is categorized under CWE-121 as a stack-based buffer overflow, where insufficient space allocation in the buffer leads to memory corruption that can be leveraged for privilege escalation.
The operational impact of this vulnerability extends beyond simple local privilege escalation as it fundamentally compromises system integrity and security posture. Attackers can exploit this flaw to execute malicious code with root privileges, potentially leading to complete system compromise, data exfiltration, and persistent backdoor establishment. The vulnerability affects systems running IBM AIX 4.3.x and 5.1 versions, which were widely deployed in enterprise environments during that timeframe, making it a significant concern for organizations maintaining legacy systems. The exploitability of this vulnerability is enhanced by the fact that it requires minimal privileges to initiate, and the LANG environment variable is commonly used by system processes, providing multiple attack vectors for exploitation.
Mitigation strategies for CVE-2001-0533 should prioritize immediate patching of affected IBM AIX systems through official IBM security updates. Organizations should implement strict environment variable validation and monitoring to prevent malicious inputs from reaching vulnerable system components. System administrators should also consider implementing privilege separation mechanisms and limiting the scope of user environment variables that can affect system libraries. From an operational security perspective, this vulnerability aligns with ATT&CK technique T1068 which covers privilege escalation through local exploitation, and T1059 which encompasses command and scripting interfaces. The incident response approach should include comprehensive system auditing to identify any potential exploitation attempts and implementation of network monitoring to detect anomalous behavior patterns associated with privilege escalation activities. Additionally, organizations should conduct regular security assessments to identify similar buffer overflow vulnerabilities in other system libraries and applications to prevent similar incidents in the future.