CVE-2005-2854 in chfeedback.pl Feedback Form Perl Script
Summary
by MITRE
CRLF injection vulnerability in thesitewizard.com chfeedback.pl Feedback Form Perl Script 2.0.1 allows remote attackers to use the script as a mail relay (spam proxy) via CRLF sequences in the (1) name or (2) email fields, which are injected into mail headers.
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Analysis
by VulDB Data Team • 07/27/2017
The vulnerability described in CVE-2005-2854 represents a critical cross-site scripting and mail relay vulnerability affecting thesitewizard.com chfeedback.pl Feedback Form Perl Script version 2.0.1. This flaw exists within the script's handling of user input in the name and email fields of a feedback form, where the application fails to properly sanitize or validate input data before incorporating it into email headers. The vulnerability falls under the category of CWE-113, which specifically addresses improper neutralization of CRLF characters in HTTP headers, making it a direct descendant of the well-known CRLF injection vulnerability pattern. The attack vector involves remote adversaries who can manipulate the feedback form to inject carriage return line feed sequences into the mail headers, effectively allowing them to craft malicious email messages that appear to originate from legitimate sources.
The technical implementation of this vulnerability exploits the fundamental weakness in the script's input processing methodology where user-supplied data flows directly into email header construction without proper sanitization. When an attacker submits malicious input containing CRLF sequences in either the name or email field, these sequences are interpreted by the mail transfer agent as command terminators rather than regular text. This allows the attacker to inject additional mail headers or modify existing ones, potentially creating a mail relay mechanism that can be exploited for spam distribution. The vulnerability demonstrates a classic lack of input validation and output encoding practices that are fundamental to secure coding standards, particularly those outlined in the OWASP Top Ten and the CERT Secure Coding Standards.
The operational impact of this vulnerability extends beyond simple spam relay capabilities to potentially enable more sophisticated attack scenarios including email spoofing, phishing campaigns, and abuse of the legitimate website's reputation. Attackers can leverage this vulnerability to send spam messages that appear to come from the compromised website, thereby damaging the site's reputation and potentially leading to blacklisting by email providers. The vulnerability also creates a persistent threat vector where the compromised script can be used repeatedly by different attackers, making it a particularly dangerous exposure for the website owner. This type of vulnerability aligns with ATT&CK technique T1192, which describes the use of compromised systems for spam relay operations, and represents a significant escalation from basic web application vulnerabilities to more serious infrastructure abuse scenarios.
Mitigation strategies for this vulnerability require immediate implementation of input sanitization measures including the removal or encoding of CRLF characters from user input fields before processing. The most effective approach involves implementing strict input validation that rejects or filters out any sequences containing carriage return or line feed characters from the name and email fields. Additionally, the script should employ proper header construction techniques that separate user input from header fields entirely, using dedicated functions or libraries designed to handle email headers safely. Organizations should also consider implementing rate limiting and monitoring for unusual email sending patterns that could indicate abuse of the feedback form. The vulnerability highlights the importance of following secure coding practices as outlined in the OWASP Secure Coding Practices and demonstrates the critical need for input validation in web applications, particularly those handling user-generated content that interfaces with external systems such as mail servers.