CVE-2012-2139 in Mail gem
Summary
by MITRE
Directory traversal vulnerability in lib/mail/network/delivery_methods/file_delivery.rb in the Mail gem before 2.4.4 for Ruby allows remote attackers to read arbitrary files via a .. (dot dot) in the to parameter.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-2139 represents a critical directory traversal flaw within the Mail gem for Ruby, specifically affecting versions prior to 2.4.4. This vulnerability resides in the file delivery method implementation located at lib/mail/network/delivery_methods/file_delivery.rb, where the application fails to properly sanitize user input before processing file paths. The flaw enables remote attackers to exploit the system by crafting malicious input containing .. (dot dot) sequences in the to parameter, which can be manipulated to traverse directories and access arbitrary files on the server filesystem.
The technical exploitation of this vulnerability occurs when the Mail gem processes email delivery requests and fails to validate or sanitize the recipient address parameter. When a .. sequence is included in the to parameter, the application does not properly restrict path traversal operations, allowing attackers to navigate beyond the intended directory boundaries. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability essentially allows attackers to bypass normal access controls and potentially read sensitive files such as configuration files, database credentials, application source code, or other confidential data stored on the server.
From an operational impact perspective, this vulnerability poses significant risks to email server security and data integrity. Attackers could leverage this flaw to extract sensitive information from the server, potentially including database connection strings, API keys, private certificates, or application configuration files that contain critical system information. The remote nature of the attack means that an attacker does not need local system access or authentication credentials to exploit the vulnerability, making it particularly dangerous in multi-tenant environments or shared hosting scenarios. The vulnerability can be exploited through various attack vectors including web applications that utilize the Mail gem for sending emails, potentially leading to data breaches, system compromise, or further lateral movement within compromised networks.
Organizations utilizing the Mail gem in their Ruby applications should immediately implement mitigations to address this vulnerability. The primary and most effective solution involves upgrading to Mail gem version 2.4.4 or later, which includes proper input sanitization and path validation mechanisms. Additionally, administrators should implement proper input validation at multiple layers of their applications, ensuring that all user-supplied data is properly sanitized before being processed by the mail delivery system. Network-level mitigations such as implementing web application firewalls and intrusion detection systems can provide additional protection against exploitation attempts. Security monitoring should be enhanced to detect unusual patterns in email delivery requests that may indicate attempted directory traversal attacks. The vulnerability also highlights the importance of following secure coding practices and conducting regular security assessments of third-party libraries to prevent similar issues from occurring in production environments. This incident aligns with ATT&CK technique T1083, which involves discovering file and directory permissions, as attackers can use directory traversal to gain unauthorized access to files that should be restricted, and T1566, which encompasses social engineering techniques used to deliver malware or exploit vulnerabilities in applications.