CVE-2000-1109 in Midnight Commander
Summary
by MITRE
Midnight Commander (mc) 4.5.51 and earlier does not properly process malformed directory names when a user opens a directory, which allows other local users to gain privileges by creating directories that contain special characters followed by the commands to be executed.
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Analysis
by VulDB Data Team • 07/19/2019
The vulnerability identified as CVE-2000-1109 represents a critical privilege escalation flaw within Midnight Commander version 4.5.51 and earlier releases. This issue stems from inadequate input validation mechanisms within the file manager's directory handling routines, specifically when processing directory names containing special characters. The flaw exists in the command execution pipeline where the application fails to properly sanitize directory names before attempting to process them, creating an environment where maliciously crafted directory names can be exploited to execute arbitrary commands with elevated privileges. This vulnerability operates under the principle of command injection, where user-controlled input is directly incorporated into system commands without proper sanitization or validation.
The technical implementation of this vulnerability exploits the way Midnight Commander handles directory traversal and command execution sequences. When a user attempts to open a directory containing special characters such as semicolons, ampersands, or other shell metacharacters, the application processes these characters as part of the command execution flow rather than as literal directory name components. This occurs because the software does not properly escape or quote directory names when they are passed to underlying system commands, allowing attackers to inject additional commands that execute with the privileges of the running mc process. The vulnerability specifically affects local users who can create directories with malicious naming conventions, leveraging the application's failure to validate or sanitize directory names before processing them through shell execution contexts.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and unauthorized access to sensitive resources. Local attackers can exploit this flaw to execute arbitrary code with the privileges of the Midnight Commander process, which typically runs with elevated permissions when used in multi-user environments. This could result in unauthorized data access, system file modification, or even complete system compromise depending on the privileges of the mc process. The vulnerability is particularly dangerous in environments where Midnight Commander is used with elevated privileges or in multi-user systems where different users share the same system resources. Attackers can leverage this weakness to establish persistent access, escalate privileges beyond their initial scope, and potentially move laterally within the network infrastructure.
Mitigation strategies for CVE-2000-1109 should focus on immediate software updates to versions that properly sanitize directory names and implement proper input validation. System administrators should ensure that all instances of Midnight Commander are updated to versions released after the vulnerability disclosure, as the fix typically involves implementing proper shell escaping mechanisms and input validation routines. Additional protective measures include implementing restrictive file system permissions, monitoring for unusual directory creation patterns, and employing automated security scanning tools to identify potentially malicious directory names. Organizations should also consider implementing privilege separation techniques where file managers run with minimal necessary privileges, reducing the potential impact of such vulnerabilities. This vulnerability aligns with CWE-78 which describes improper neutralization of special elements used in OS commands, and represents a classic example of how insufficient input validation can lead to command injection attacks. The ATT&CK framework categorizes this under privilege escalation techniques, specifically focusing on the use of local tools and utilities to gain elevated system access.