CVE-2012-2140 in Mail gem
Summary
by MITRE
The Mail gem before 2.4.3 for Ruby allows remote attackers to execute arbitrary commands via shell metacharacters in a (1) sendmail or (2) exim delivery.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-2140 represents a critical command injection flaw in the Mail gem version 2.4.2 and earlier for the Ruby programming language. This vulnerability specifically affects the gem's handling of email delivery mechanisms, particularly when utilizing sendmail or exim as delivery methods. The flaw arises from insufficient input validation and sanitization within the gem's delivery processing logic, creating a pathway for remote attackers to inject malicious shell commands through carefully crafted email parameters.
The technical implementation of this vulnerability stems from the Mail gem's improper handling of user-supplied data during the email delivery process. When the gem processes email messages for delivery via sendmail or exim, it fails to adequately sanitize or escape shell metacharacters present in email headers or content. This inadequate sanitization allows attackers to inject arbitrary shell commands that get executed by the underlying system's shell, effectively granting remote code execution capabilities. The vulnerability is classified as a command injection flaw, aligning with CWE-77 and CWE-88 categories that specifically address improper neutralization of special elements used in shell commands.
The operational impact of CVE-2012-2140 extends beyond simple remote code execution to encompass potential system compromise and data exfiltration. Attackers exploiting this vulnerability can execute arbitrary commands with the privileges of the user running the Ruby application, potentially leading to full system compromise. The vulnerability affects web applications that utilize the Mail gem for email functionality, particularly those that accept user input in email headers or content fields. This creates a significant risk for applications handling user-generated content or those that process emails from untrusted sources, as the attack surface expands to include any email processing functionality.
Security practitioners should prioritize immediate remediation of this vulnerability by upgrading to Mail gem version 2.4.3 or later, which includes proper input sanitization and command escaping mechanisms. The mitigation strategy should also include implementing network-level controls such as firewalls and intrusion detection systems to monitor for suspicious command execution patterns. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all applications utilizing the vulnerable Mail gem version and ensure proper input validation is implemented at multiple layers of the application architecture. This vulnerability demonstrates the critical importance of secure coding practices in library development and highlights the need for proper input validation, especially when dealing with system-level operations and external command execution. The ATT&CK framework categorizes this vulnerability under T1059.001 (Command and Scripting Interpreter: Shell Script) as it enables adversaries to execute shell commands through the vulnerable delivery mechanisms, potentially leading to further compromise and lateral movement within affected environments.