CVE-2001-0420 in Talkback
Summary
by MITRE
Directory traversal vulnerability in talkback.cgi program allows remote attackers to read arbitrary files via a .. (dot dot) in the article parameter.
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Analysis
by VulDB Data Team • 06/03/2019
The CVE-2001-0420 vulnerability represents a classic directory traversal flaw in the talkback.cgi web application, which was widely deployed in early web server environments. This vulnerability resides within the input validation mechanisms of the talkback.cgi program, specifically in how it processes the article parameter. The flaw allows remote attackers to manipulate file paths by inserting directory traversal sequences such as .. or ../ into the article parameter, enabling them to navigate beyond the intended directory boundaries and access arbitrary files on the server filesystem. The vulnerability is particularly dangerous because it operates at the core of file access controls, potentially exposing sensitive system files, configuration data, or user information that should remain protected.
The technical implementation of this vulnerability stems from inadequate input sanitization and path validation within the talkback.cgi script. When the application receives a request containing an article parameter with traversal sequences, it fails to properly validate or sanitize the input before using it in file operations. This allows the attacker to craft malicious URLs that bypass normal file access restrictions, effectively performing a path traversal attack that maps to the underlying file system structure. The vulnerability is classified under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. This weakness enables attackers to access files outside the web root directory, potentially including system configuration files, password files, or other sensitive data that should be protected from unauthorized access.
The operational impact of CVE-2001-0420 extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other vulnerabilities or attack vectors. An attacker exploiting this vulnerability can potentially read critical system files such as /etc/passwd, /etc/shadow, or application configuration files that contain database credentials or other sensitive information. The vulnerability also opens the door for further exploitation, as attackers might use the discovered information to escalate privileges or gain deeper access to the system. From an attack framework perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1083 (File and Directory Discovery) and T1566 (Phishing) tactics, as it enables attackers to discover and access files that might contain credentials or other sensitive data. The vulnerability's exploitation is particularly concerning in environments where the web server has elevated privileges, as it can potentially allow attackers to read files that are normally restricted to system administrators.
Mitigation strategies for CVE-2001-0420 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from occurring in modern applications. The primary fix involves implementing robust input validation and sanitization mechanisms that reject or properly encode directory traversal sequences in all user-supplied parameters. This includes implementing proper path validation that ensures file operations occur within designated directories and reject any attempts to traverse beyond these boundaries. Organizations should also consider implementing principle of least privilege for web applications, ensuring that the web server process runs with minimal required permissions and cannot access sensitive system files. Additionally, the vulnerability highlights the importance of regular security assessments and code reviews, particularly focusing on input validation and file access controls. Modern security practices should incorporate automated tools that can detect such path traversal vulnerabilities during development and deployment phases, reducing the likelihood of similar issues in contemporary applications. The vulnerability also underscores the need for proper security training for developers to understand the implications of inadequate input validation and the potential consequences of path traversal attacks in web applications.