CVE-2000-1013 in FreeBSD
Summary
by MITRE
The setlocale function in FreeBSD 5.0 and earlier, and possibly other OSes, allows local users to read arbitrary files via the LANG environmental variable.
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Analysis
by VulDB Data Team • 02/13/2017
The vulnerability described in CVE-2000-1013 represents a critical security flaw in the setlocale function implementation across FreeBSD versions 5.0 and earlier, with potential impacts extending to other operating systems. This vulnerability stems from improper handling of locale settings through the LANG environment variable, creating an arbitrary file read condition that can be exploited by local attackers to access sensitive system files. The flaw exists in the internationalization subsystem of these operating systems, specifically in how the system processes locale configuration data during application execution.
The technical root cause of this vulnerability lies in the insecure parsing and processing of the LANG environment variable within the setlocale function. When applications attempt to set locale parameters, the system fails to properly validate or sanitize the input provided through this environmental variable. This allows attackers to craft malicious locale specifications that cause the system to inadvertently read and expose file contents from arbitrary locations within the filesystem. The vulnerability operates at the operating system level rather than application level, making it particularly dangerous as it can be exploited across multiple applications running on the affected system.
From an operational perspective, this vulnerability presents significant risks to system security and data confidentiality. Local attackers with basic user privileges can exploit this flaw to gain unauthorized access to sensitive files that would normally be protected by standard file permissions. The impact extends beyond simple information disclosure, as attackers may be able to read configuration files, password databases, or other critical system resources that could facilitate further exploitation. This vulnerability directly violates the principle of least privilege and undermines the security model of the affected operating systems, potentially enabling privilege escalation or lateral movement within compromised environments.
The vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and represents a classic example of how internationalization features can introduce security weaknesses when not properly implemented. From an attacker's perspective, this vulnerability maps to techniques described in the MITRE ATT&CK framework under T1059 for command and scripting interpreter and T1074 for data staging, as it enables initial access to system files that can be used for further reconnaissance and exploitation. The low complexity and high impact nature of this vulnerability makes it particularly attractive to threat actors seeking to establish persistent access or extract sensitive information from compromised systems.
Mitigation strategies for this vulnerability include immediate patching of affected FreeBSD systems to version 5.1 or later where the issue has been resolved through proper input validation and sanitization of the LANG environment variable. System administrators should also implement strict environment variable controls and monitor for unusual locale settings in system logs. Additional protective measures include restricting user privileges, implementing mandatory access controls, and regularly auditing system configurations to prevent unauthorized modification of locale settings. The vulnerability demonstrates the importance of security reviews during internationalization implementation and the necessity of proper input validation in all system components that handle user-supplied data.