CVE-2001-0937 in PGPMail
Summary
by MITRE
PGPMail.pl 1.31 allows remote attackers to execute arbitrary commands via shell metacharacters in the (1) recipient or (2) pgpuserid parameters.
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Analysis
by VulDB Data Team • 05/10/2019
The vulnerability identified as CVE-2001-0937 represents a critical command injection flaw in PGPMail.pl version 1.31, a web-based email encryption utility that facilitates secure communication through PGP encryption. This vulnerability exists within the input validation mechanisms of the script, specifically affecting two parameter fields: recipient and pgpuserid. The flaw allows remote attackers to execute arbitrary commands on the target system by injecting shell metacharacters into these parameters, effectively bypassing the intended security boundaries of the application.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied input within the PGPMail.pl script. When the application processes the recipient or pgpuserid parameters, it fails to properly validate or escape special shell characters such as semicolons, ampersands, backticks, or pipes. These metacharacters are interpreted by the underlying shell as command separators or operators, enabling attackers to append malicious commands that execute with the privileges of the web server process. The vulnerability operates at the application level where user input flows directly into system commands without adequate filtering or escaping mechanisms, creating a classic command injection attack vector.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with arbitrary code execution capabilities on the affected system. Successful exploitation could lead to complete system compromise, allowing attackers to access sensitive data, install backdoors, modify system configurations, or launch further attacks against network infrastructure. The remote nature of the attack means that exploitation can occur from anywhere on the internet without requiring local access or authentication. This vulnerability directly maps to CWE-77 which describes improper neutralization of special elements used in a command, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The vulnerability affects the confidentiality, integrity, and availability of the targeted system, potentially enabling data breaches, service disruption, and persistent access to the compromised environment.
Mitigation strategies for this vulnerability must address both the immediate security gap and establish long-term defensive measures. The primary remediation involves implementing proper input validation and sanitization for all user-supplied parameters, ensuring that shell metacharacters are either escaped or removed from input before processing. Organizations should upgrade to a patched version of PGPMail.pl or migrate to more modern secure email encryption solutions. Additional defensive measures include implementing web application firewalls, restricting file permissions on the web server, and employing principle of least privilege for the web server account. Network segmentation and monitoring should be enhanced to detect suspicious command execution patterns. The vulnerability highlights the critical importance of secure coding practices and input validation in web applications, particularly those handling sensitive data or executing system commands, and serves as a reminder of the potential catastrophic consequences when such fundamental security controls are absent from applications processing user input.