CVE-2009-1591 in Cgi Web Mailer
Summary
by MITRE
CRLF injection vulnerability in CGI RESCUE Web Mailer before 1.04 allows remote attackers to inject arbitrary HTTP headers, and conduct cross-site scripting (XSS) or HTTP response splitting attacks, via CRLF sequences in an unspecified web form.
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Analysis
by VulDB Data Team • 12/10/2017
The CVE-2009-1591 vulnerability represents a critical CRLF injection flaw in the CGI RESCUE Web Mailer version 1.03 and earlier, demonstrating a fundamental weakness in input validation and output encoding mechanisms. This vulnerability stems from improper handling of carriage return line feed sequences within web forms, allowing attackers to inject malicious CRLF characters that can manipulate HTTP responses. The flaw exists at the application level where user-supplied data is directly incorporated into HTTP headers without adequate sanitization, creating a pathway for attackers to manipulate the HTTP protocol itself. The vulnerability specifically affects the web mailer's processing of unspecified web forms, suggesting that multiple input vectors could be exploited to achieve the same malicious outcomes. This type of vulnerability is categorized under CWE-113, which addresses improper neutralization of CRLF sequences in HTTP headers, making it a well-documented pattern in web application security.
The technical exploitation of this vulnerability enables attackers to perform HTTP response splitting attacks, where they can inject multiple HTTP responses into a single HTTP transaction, potentially leading to cache poisoning or session hijacking. Additionally, the CRLF injection allows for cross-site scripting attacks by injecting malicious script code into HTTP headers that are subsequently processed by web browsers. The attack vector requires minimal privileges as it operates through standard web form submissions, making it particularly dangerous for web applications that process user input without proper validation. The vulnerability essentially allows attackers to manipulate the HTTP protocol at the application layer, bypassing standard security mechanisms designed to prevent such header injection attacks. This type of attack falls under the ATT&CK technique T1071.004 for Application Layer Protocol and T1566 for Phishing, as it enables the delivery of malicious content through compromised web applications.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it provides attackers with the capability to perform more sophisticated attacks such as session fixation, cache poisoning, and redirect attacks. When combined with other vulnerabilities, the CRLF injection can enable attackers to manipulate web application behavior in ways that compromise user sessions and data integrity. The vulnerability affects web applications that rely on CGI-based mailers for user communication, making it particularly concerning for organizations that depend on legacy web mailer systems. The risk is amplified by the fact that the vulnerability can be exploited through multiple input points, increasing the attack surface for potential exploitation. Organizations using affected versions of CGI RESCUE Web Mailer face significant risks including data leakage, unauthorized access, and potential system compromise. The vulnerability also impacts the application's ability to maintain secure HTTP headers, which are fundamental to web security protocols and user trust mechanisms.
Mitigation strategies for CVE-2009-1591 primarily involve immediate patching of the affected software to version 1.04 or later, which contains proper input validation and sanitization mechanisms. Organizations should implement comprehensive input validation that filters or encodes CRLF characters in all user-supplied data before processing. Additionally, proper HTTP header encoding techniques should be implemented to prevent CRLF sequences from being interpreted as part of the HTTP protocol. The implementation of web application firewalls and security monitoring systems can help detect and prevent exploitation attempts. Organizations should also conduct thorough security assessments of their web applications to identify similar vulnerabilities in other components and ensure that all user input is properly sanitized before being incorporated into HTTP responses. The vulnerability highlights the importance of following secure coding practices and adhering to OWASP Top 10 security guidelines, particularly those related to input validation and output encoding. Regular security updates and vulnerability management processes are essential to prevent exploitation of such legacy vulnerabilities in web applications.