CVE-2000-0877 in MailForm
Summary
by MITRE
mailform.pl CGI script in MailForm 2.0 allows remote attackers to read arbitrary files by specifying the file name in the XX-attach_file parameter, which MailForm then sends to the attacker.
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Analysis
by VulDB Data Team • 05/28/2019
The vulnerability identified as CVE-2000-0877 represents a critical directory traversal flaw in the mailform.pl CGI script bundled with MailForm 2.0 software. This vulnerability falls under the category of insecure direct object references and allows remote attackers to bypass normal access controls and retrieve arbitrary files from the server filesystem. The flaw specifically manifests when the XX-attach_file parameter is manipulated to include directory traversal sequences such as ../ or ..\, enabling attackers to navigate outside the intended directory structure and access sensitive files that should remain protected. This type of vulnerability is classified as CWE-22, known as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')".
The technical implementation of this vulnerability exploits the lack of proper input validation within the mailform.pl script. When users submit forms through the MailForm application, the script processes the XX-attach_file parameter without adequate sanitization or validation of the file path provided. The application directly incorporates this parameter into file operations, creating an opportunity for attackers to specify absolute or relative paths that traverse the filesystem. This behavior aligns with ATT&CK technique T1059.007, where adversaries leverage command and scripting interfaces to execute malicious code, though in this case the exploitation involves file system traversal rather than command execution. The vulnerability essentially allows an attacker to perform a form of file inclusion attack where the target system attempts to read and process files that are not intended to be accessible through the web interface.
The operational impact of CVE-2000-0877 extends far beyond simple information disclosure, as it can potentially expose sensitive system files including configuration data, authentication credentials, database connection details, and other confidential information. Attackers could leverage this vulnerability to access password files, system configuration scripts, application source code, and potentially even system binaries that could provide additional attack vectors. The vulnerability affects any system running MailForm 2.0 with the vulnerable mailform.pl script, making it particularly dangerous as it could be exploited by automated scanners that target known vulnerable applications. The attack surface is broad since many organizations have legacy web applications that may still be running unpatched versions of MailForm or similar vulnerable CGI scripts, creating persistent exposure windows for attackers who maintain lists of such vulnerabilities.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The primary solution involves applying the official patch provided by the software vendor or upgrading to a newer version of MailForm that properly validates and sanitizes file paths before processing. Organizations should implement input validation controls that reject or normalize any path traversal sequences in user-supplied parameters, ensuring that all file operations occur within designated safe directories. This approach aligns with security best practices outlined in the OWASP Top Ten and follows the principle of least privilege by restricting file system access to only necessary directories. Network-level mitigations such as web application firewalls and intrusion prevention systems can provide additional layers of defense by monitoring for suspicious path traversal patterns in HTTP requests. Regular security assessments and vulnerability scanning should be implemented to identify other potentially vulnerable applications, as this vulnerability type remains common in legacy web applications and underscores the importance of maintaining up-to-date software inventory and patch management processes. The vulnerability also highlights the necessity of proper application security training for developers to prevent similar flaws in custom web applications that may be developed in-house or by third-party vendors.