CVE-2011-0739 in Mail
Summary
by MITRE
The deliver function in the sendmail delivery agent (lib/mail/network/delivery_methods/sendmail.rb) in Ruby Mail gem 2.2.14 and earlier allows remote attackers to execute arbitrary commands via shell metacharacters in an e-mail address.
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Analysis
by VulDB Data Team • 10/13/2021
The vulnerability identified as CVE-2011-0739 represents a critical command injection flaw within the Ruby Mail gem, specifically affecting versions 2.2.14 and earlier. This issue resides in the deliver function of the sendmail delivery agent, which is part of the mail library's network delivery methods. The vulnerability stems from insufficient input validation and sanitization of email addresses, creating an avenue for remote attackers to inject malicious shell commands through specially crafted email address strings containing shell metacharacters.
The technical implementation of this vulnerability occurs when the Ruby Mail gem processes email addresses through the sendmail delivery mechanism. When an application using this gem attempts to deliver mail to an address containing shell metacharacters such as semicolons, ampersands, or backticks, the gem fails to properly escape or validate these characters before passing them to the underlying sendmail command. This lack of proper sanitization allows attackers to manipulate the command execution flow and inject arbitrary shell commands that get executed with the privileges of the mail delivery process.
The operational impact of this vulnerability extends beyond simple command execution, as it can enable full system compromise when the mail delivery process runs with elevated privileges. Attackers can leverage this flaw to execute arbitrary code on the server, potentially leading to unauthorized access, data exfiltration, or system takeover. The vulnerability is particularly dangerous in web applications that process user-supplied email addresses, as it allows for remote code execution without requiring authentication or specific user interaction beyond sending a malicious email. This makes it a high-severity issue that can be exploited by attackers with minimal privileges.
Security professionals should note this vulnerability aligns with CWE-77 and CWE-94 categories, representing command injection and code injection weaknesses respectively. The attack pattern follows the ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting the command shell. Organizations using the affected Ruby Mail gem versions should immediately upgrade to patched releases, implement input validation at application level, and consider network segmentation to limit potential impact. Additionally, monitoring for suspicious email address patterns and implementing proper email address validation can help detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of proper input sanitization in mail processing libraries and highlights the risks associated with shell command execution in interpreted languages.