CVE-2000-1011 in FreeBSD
Summary
by MITRE
Buffer overflow in catopen() function in FreeBSD 5.0 and earlier, and possibly other OSes, allows local users to gain root privileges via a long environmental variable.
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Analysis
by VulDB Data Team • 05/28/2018
The vulnerability described in CVE-2000-1011 represents a critical buffer overflow flaw within the catopen() function of FreeBSD systems running version 5.0 and earlier, with potential impacts extending to other operating systems. This issue stems from inadequate input validation when processing environmental variables, creating a pathway for malicious exploitation that can result in privilege escalation. The catopen() function is part of the X/Open Common Applications Programming Interface and is used to open message catalog files, which are essential for internationalization and localization of applications. When a local user provides a specially crafted environmental variable containing excessive data, the function fails to properly bounds-check the input, leading to memory corruption that can be leveraged for unauthorized system access.
The technical exploitation of this vulnerability occurs through the manipulation of environmental variables, specifically targeting the way the catopen() function handles string inputs. The flaw manifests as a classic stack-based buffer overflow where the excessive input overwrites adjacent memory locations, potentially including return addresses or other critical control data. This type of vulnerability falls under CWE-121, which categorizes buffer overflow conditions that occur when a program writes data beyond the boundaries of a fixed-length buffer. The attack vector is particularly insidious because it requires no network connectivity and can be executed locally, making it a significant concern for system administrators who may not expect such vulnerabilities to exist in system libraries that are fundamental to operating system functionality.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to gain root access to affected systems, potentially compromising entire networks. Once an attacker achieves root privileges through this vector, they can modify system files, install malicious software, create new user accounts, or completely disable system services. The vulnerability affects systems where applications rely on the catopen() function for internationalization purposes, which includes many standard system utilities and applications that handle localized text output. Given that this vulnerability was present in FreeBSD 5.0 and earlier versions, organizations running these systems faced a significant risk of compromise, particularly in environments where local access was possible or where applications were not properly sandboxed from potentially malicious environmental inputs.
Mitigation strategies for CVE-2000-1011 focus primarily on patching the affected systems and implementing proper input validation practices. System administrators should immediately upgrade to FreeBSD versions that contain the necessary security patches, as the vulnerability was addressed in subsequent releases. Additionally, organizations should implement strict environmental variable validation and sanitization processes, particularly for applications that interface with internationalization libraries. The principle of least privilege should be enforced to limit the potential damage from successful exploitation, and monitoring systems should be configured to detect unusual patterns in environmental variable usage. This vulnerability also highlights the importance of secure coding practices and proper bounds checking in system libraries, as outlined in the software security guidelines that align with ATT&CK technique T1068, which covers privilege escalation through local exploitation of system vulnerabilities. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability has been fully addressed without introducing regressions in system functionality.