CVE-2006-3174 in SquirrelMail
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in search.php in SquirrelMail 1.5.1 and earlier, when register_globals is enabled, allows remote attackers to inject arbitrary HTML via the mailbox parameter.
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Analysis
by VulDB Data Team • 07/14/2019
The vulnerability identified as CVE-2006-3174 represents a classic cross-site scripting flaw within the SquirrelMail web-based email client version 1.5.1 and earlier. This security weakness specifically affects installations where the PHP configuration parameter register_globals is enabled, creating a dangerous condition that enables malicious actors to execute arbitrary HTML code through crafted input vectors. The vulnerability manifests in the search.php script, which processes user input without proper sanitization mechanisms, particularly when handling the mailbox parameter.
The technical exploitation of this vulnerability occurs due to the insecure handling of user-supplied data within the SquirrelMail application framework. When register_globals is enabled, PHP automatically creates global variables from request data, including GET and POST parameters, which can override existing variables and create unexpected behavior in the application's input validation processes. The mailbox parameter in search.php becomes a conduit for malicious input, as the application fails to properly escape or filter user-provided content before rendering it within the web interface. This flaw directly maps to CWE-79, which defines Cross-Site Scripting as a weakness where untrusted data is embedded into web pages viewed by other users without proper sanitization, allowing attackers to inject malicious scripts.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to execute arbitrary code within the context of a victim's browser session. An attacker could craft a malicious URL containing script tags that would execute when a user accesses the search functionality, potentially stealing session cookies, redirecting users to malicious sites, or performing actions on behalf of authenticated users. The vulnerability is particularly concerning in environments where SquirrelMail is used for corporate email services, as it could allow attackers to compromise user sessions and potentially gain access to sensitive email communications. The attack vector is relatively simple and does not require elevated privileges, making it accessible to attackers with basic web exploitation knowledge.
Mitigation strategies for this vulnerability should focus on immediate remediation actions including disabling the register_globals PHP configuration parameter, which fundamentally eliminates the root cause of the vulnerability. Organizations should upgrade to SquirrelMail versions 1.5.2 or later where this vulnerability has been addressed through proper input sanitization and output encoding mechanisms. Additionally, implementing proper input validation and output escaping techniques, such as those recommended by the OWASP Secure Coding Practices, would prevent similar vulnerabilities from occurring in other applications. Network-based protections like web application firewalls can provide additional defense-in-depth, though they should not be relied upon as the sole remediation measure. The vulnerability demonstrates the critical importance of proper secure coding practices and the dangers of legacy PHP configurations that can introduce unexpected security weaknesses into web applications. This issue aligns with ATT&CK technique T1566, which covers the exploitation of vulnerabilities for initial access, and highlights the necessity of maintaining up-to-date software components to prevent exploitation of known weaknesses.