CVE-2000-0460 in KDE
Summary
by MITRE
Buffer overflow in KDE kdesud on Linux allows local uses to gain privileges via a long DISPLAY environmental variable.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2000-0460 represents a critical buffer overflow flaw within the KDE kdesud daemon on Linux systems. This issue specifically affects the kdesud component which serves as a privileged helper program for the KDE desktop environment, responsible for executing administrative tasks on behalf of users. The vulnerability arises from insufficient input validation when processing the DISPLAY environment variable, a standard mechanism used by X Window System applications to identify the display server they should communicate with. When a local user provides an excessively long DISPLAY variable value, the kdesud daemon fails to properly bounds-check the input, leading to memory corruption that can be exploited to escalate privileges.
The technical implementation of this vulnerability stems from the daemon's handling of environment variables without adequate length validation. The kdesud process, which runs with elevated privileges to perform system administration tasks, accepts user-provided DISPLAY values through the environment without proper sanitization. This creates a classic buffer overflow scenario where the fixed-size buffer allocated for the DISPLAY variable can be overwritten by user-controlled data exceeding its capacity. The overflow occurs in the daemon's argument processing code, where it directly copies the DISPLAY environment variable into a local buffer without checking the source length against the buffer size. This flaw operates at the system level and can be exploited by any local user to gain elevated privileges, making it particularly dangerous in multi-user environments where users might attempt to leverage such weaknesses for unauthorized access.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security model of the KDE desktop environment. When successfully exploited, local users can execute arbitrary code with the privileges of the kdesud daemon, which typically runs with root-level permissions. This allows attackers to perform actions such as modifying system files, installing malicious software, or creating new user accounts with administrative rights. The vulnerability affects systems running KDE desktop environments on Linux platforms, particularly those configured to use the kdesud service for system administration tasks. The exploitability is relatively straightforward since it only requires local access and the ability to set environment variables, making it accessible to users who may not have direct administrative privileges but wish to escalate their access level within the system.
Mitigation strategies for CVE-2000-0460 focus on both immediate patching and operational security measures. The most effective solution involves applying the appropriate security patches released by KDE developers and Linux distributions to address the buffer overflow in kdesud. Organizations should also implement proper input validation mechanisms for environment variables and consider disabling unnecessary privileged helper services when they are not actively required. System administrators can employ monitoring tools to detect unusual environment variable usage patterns and implement mandatory access controls to limit the potential damage from such exploits. Additionally, the vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and relates to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' through local system vulnerabilities. Regular security audits and vulnerability assessments should include checks for outdated desktop environment components that may contain similar buffer overflow flaws, as this represents a common class of vulnerability in desktop application frameworks that handle user input.