CVE-2006-4344 in Mail F W System
Summary
by MITRE
CRLF injection vulnerability in CGI-Rescue Mail F/W System (formd) before 8.3 allows remote attackers to spoof e-mails and inject e-mail headers via unspecified vectors in (1) mail.cgi and (2) query.cgi.
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Analysis
by VulDB Data Team • 09/23/2017
The CVE-2006-4344 vulnerability represents a critical cross-site scripting and email header injection flaw within the CGI-Rescue Mail Firewall System's formd component. This vulnerability specifically affects versions prior to 8.3 and operates through CRLF (Carriage Return Line Feed) injection techniques that exploit improper input validation in the mail.cgi and query.cgi scripts. The vulnerability stems from insufficient sanitization of user-supplied input parameters that are directly incorporated into email headers without proper encoding or validation mechanisms.
The technical implementation of this vulnerability occurs when attackers can manipulate input fields within the mail and query forms to inject CRLF sequences into email headers. This allows malicious actors to insert arbitrary email headers, manipulate email routing, or inject additional email content that can be interpreted by email clients and servers. The flaw operates at the application layer where user input flows directly into email generation processes without adequate sanitization, creating a pathway for header injection attacks that fall under CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers. The vulnerability specifically targets the email header injection vector where attackers can manipulate the From, To, Subject, or other email header fields to redirect or manipulate email flow.
The operational impact of this vulnerability extends beyond simple email spoofing to encompass potential email relay abuse, spam distribution, and credential harvesting. Attackers can leverage this flaw to send phishing emails that appear to originate from legitimate sources, manipulate email delivery paths, or even inject malicious content that could compromise email clients or servers. The vulnerability creates opportunities for man-in-the-middle attacks against email communications, where malicious actors can intercept and modify email headers to redirect messages or inject harmful content. This vulnerability directly maps to ATT&CK technique T1190 - Exploit Public-Facing Application, as it represents an unauthenticated remote code execution vector through email header manipulation. The attack surface is particularly dangerous in environments where the mail firewall system serves as a gateway for email processing, as it can enable attackers to bypass email security controls and manipulate email flows at scale.
Mitigation strategies for this vulnerability require immediate patching of the CGI-Rescue Mail Firewall System to version 8.3 or later, which contains proper input validation and sanitization mechanisms. Organizations should implement comprehensive input validation at all entry points where user data enters email processing systems, ensuring that CRLF sequences are properly escaped or removed from email header fields. Network segmentation and email filtering solutions should be deployed to monitor and detect anomalous email header patterns that might indicate exploitation attempts. Additionally, implementing email authentication mechanisms such as SPF, DKIM, and DMARC can help mitigate the impact of header injection attacks by providing verification mechanisms that can detect spoofed email sources. The remediation process must include thorough code review of all email processing components to identify and address similar input validation weaknesses that could create additional attack vectors. Security monitoring should be enhanced to detect unusual email header patterns and automated email sending activities that could indicate exploitation of this vulnerability.