CVE-2000-1207 in Linux
Summary
by MITRE
userhelper in the usermode package on Red Hat Linux executes non-setuid programs as root, which does not activate the security measures in glibc and allows the programs to be exploited via format string vulnerabilities in glibc via the LANG or LC_ALL environment variables (CVE-2000-0844).
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Analysis
by VulDB Data Team • 08/21/2017
The vulnerability described in CVE-2000-1207 represents a critical security flaw in the usermode package distribution on Red Hat Linux systems. This issue specifically affects the userhelper utility which operates with elevated privileges despite not being properly configured with setuid permissions. The flaw stems from the improper execution model where non-setuid programs are executed with root privileges, creating an environment where standard security mechanisms within glibc are bypassed. This design oversight fundamentally undermines the privilege separation model that is essential for maintaining system integrity and preventing unauthorized access to critical system resources.
The technical exploitation of this vulnerability occurs through format string vulnerabilities present in glibc, particularly when the LANG or LC_ALL environment variables are manipulated by an attacker. These environment variables are commonly used to set locale preferences for applications, but in this case they become attack vectors that can trigger buffer overflow conditions within glibc's printf family functions. When userhelper executes programs with root privileges and these programs process untrusted input through the vulnerable environment variables, attackers can craft malicious format strings that lead to arbitrary code execution with root privileges. This exploitation technique aligns with common attack patterns documented in the ATT&CK framework under privilege escalation and code injection techniques.
The operational impact of CVE-2000-1207 is severe and far-reaching, as it allows attackers to gain root access to systems running vulnerable versions of Red Hat Linux. The vulnerability essentially provides a path for privilege escalation that bypasses normal authentication and authorization mechanisms, potentially enabling complete system compromise. Once exploited, attackers can install backdoors, modify system files, access sensitive data, and establish persistent access to the compromised system. This type of vulnerability is particularly dangerous in multi-user environments where unauthorized privilege escalation can lead to widespread system compromise and data breaches.
Mitigation strategies for this vulnerability should focus on immediate patching of the usermode package to address the improper privilege execution model. System administrators should also implement environment variable sanitization to prevent malicious input from reaching vulnerable applications, particularly those that rely on locale settings. The remediation approach should include disabling unnecessary setuid programs and implementing proper privilege separation mechanisms. Additionally, organizations should consider implementing runtime protection measures such as stack canaries and address space layout randomization to make exploitation more difficult. This vulnerability demonstrates the importance of proper privilege management and the critical need for security-conscious development practices that align with secure coding standards and principles outlined in CWE categories related to privilege escalation and improper privilege handling.