CVE-2005-0107 in bmtpd
Summary
by MITRE
bsmtpd 2.3 and earlier does not properly sanitize e-mail addresses, which allows remote attackers to execute arbitrary commands.
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Analysis
by VulDB Data Team • 05/30/2019
The vulnerability identified as CVE-2005-0107 affects bsmtpd version 2.3 and earlier, representing a critical security flaw in email server software that enables remote command execution through improper email address sanitization. This vulnerability resides in the mail server's handling of email addresses during message processing, where the system fails to adequately validate or sanitize input parameters that contain email addresses. The flaw creates a dangerous condition where attacker-controlled email addresses can be manipulated to inject and execute arbitrary commands on the affected system. This type of vulnerability falls under the category of command injection attacks, which are classified as CWE-77 in the Common Weakness Enumeration catalog and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The vulnerability demonstrates a fundamental failure in input validation and sanitization practices within the mail server's processing pipeline.
The technical implementation of this vulnerability occurs when the bsmtpd server processes incoming email messages and parses email addresses contained within the message headers or body. The system does not properly escape or filter special characters that could be interpreted as command delimiters or shell metacharacters. When an attacker crafts a malicious email address containing shell injection sequences such as semicolons, ampersands, or backticks, these characters can be interpreted by the system's underlying shell commands during processing. This allows an attacker to execute arbitrary commands with the privileges of the bsmtpd process, which typically runs with elevated system permissions. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication, making it a severe threat to email server security and potentially leading to complete system compromise.
The operational impact of this vulnerability extends beyond simple command execution, as it can result in full system compromise, data exfiltration, and persistent backdoor access. Attackers can leverage this vulnerability to gain unauthorized access to the mail server, potentially using it as a stepping stone for further attacks within the network infrastructure. The compromised system may be used to relay spam emails, conduct phishing campaigns, or serve as a command and control node for other malicious activities. Organizations relying on vulnerable bsmtpd installations face significant risk of unauthorized data access, service disruption, and potential regulatory compliance violations. The vulnerability affects email infrastructure that may be critical to business operations, making it particularly concerning for enterprises that depend on reliable email communication systems.
Mitigation strategies for CVE-2005-0107 require immediate action to address the core sanitization flaw within the bsmtpd software. The most effective solution involves upgrading to a patched version of bsmtpd that implements proper input validation and sanitization of email addresses. Organizations should also implement network-level restrictions to limit access to mail server ports and consider implementing email filtering solutions that can detect and block suspicious email addresses. Additional defensive measures include configuring the system to run with minimal privileges, implementing proper input validation at multiple layers of the application, and establishing monitoring procedures to detect unusual command execution patterns. Security teams should also conduct thorough vulnerability assessments of their email infrastructure and implement proper network segmentation to limit the potential impact of successful exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation in security-critical applications and demonstrates the need for robust sanitization practices throughout all stages of software development.