CVE-1999-1586 in SunOS
Summary
by MITRE
loadmodule in SunOS 4.1.x, as used by xnews, does not properly sanitize its environment, which allows local users to gain privileges, a different vulnerability than CVE-1999-1584.
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Analysis
by VulDB Data Team • 06/23/2021
The vulnerability described in CVE-1999-1586 represents a critical privilege escalation flaw within the SunOS 4.1.x operating system's implementation of the loadmodule utility. This issue specifically affects the xnews application which utilizes the loadmodule functionality to dynamically load system modules. The core problem lies in the improper sanitization of environmental variables during the module loading process, creating a pathway for local attackers to execute arbitrary code with elevated privileges. This vulnerability operates at the system level and demonstrates a fundamental flaw in how the operating system handles environment variable processing during module initialization.
The technical exploitation of this vulnerability stems from the loadmodule function's failure to properly validate or sanitize environmental variables before passing them to system calls. When xnews invokes loadmodule, the application inherits the current environment including potentially malicious variables that can be manipulated by local users. This improper environment handling creates a condition where attacker-controlled values can influence the module loading process, potentially allowing the execution of code with root privileges. The vulnerability specifically relates to the lack of proper input validation and environment variable sanitization mechanisms, which are fundamental security controls that should prevent such privilege escalation scenarios. This flaw aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and represents a classic example of environment variable injection attacks.
The operational impact of CVE-1999-1586 is significant as it provides local attackers with a straightforward method to escalate privileges from regular user accounts to root level access. This privilege escalation capability allows malicious users to gain complete control over affected systems, potentially leading to data theft, system compromise, and further network infiltration. The vulnerability affects systems running SunOS 4.1.x versions where xnews is installed, making it particularly concerning for organizations using legacy solaris systems. The attack vector requires local system access, which means that an attacker must already have some level of access to the system, but once achieved, the privilege escalation can be used to establish persistent access or to conduct further attacks against the network infrastructure.
Mitigation strategies for this vulnerability primarily focus on implementing proper environment variable sanitization within the loadmodule function and related system utilities. System administrators should ensure that all environment variables are properly validated and sanitized before being passed to system calls that load modules or execute commands. The most effective immediate solution involves applying the appropriate security patches provided by Sun Microsystems for the affected SunOS versions. Additionally, implementing the principle of least privilege by restricting local user access to system utilities and monitoring for unusual module loading activities can help detect potential exploitation attempts. Organizations should also consider implementing runtime protection mechanisms and monitoring for suspicious environment variable modifications. This vulnerability highlights the importance of proper input validation and environment handling in system-level applications, and aligns with ATT&CK technique T1068 which covers the use of privilege escalation techniques through environment variable manipulation. The vulnerability also demonstrates the critical need for security reviews of system utilities that handle dynamic module loading and environment processing, as these components often serve as attack vectors for privilege escalation.