CVE-2019-12970 in SquirrelMail
Summary
by MITRE
XSS was discovered in SquirrelMail through 1.4.22 and 1.5.x through 1.5.2. Due to improper handling of RCDATA and RAWTEXT type elements, the built-in sanitization mechanism can be bypassed. Malicious script content from HTML e-mail can be executed within the application context via crafted use of (for example) a NOEMBED, NOFRAMES, NOSCRIPT, or TEXTAREA element.
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Analysis
by VulDB Data Team • 10/09/2023
The vulnerability CVE-2019-12970 represents a cross-site scripting flaw in SquirrelMail email client versions up to 1.4.22 and 1.5.x up to 1.5.2. This issue stems from inadequate handling of RCDATA and RAWTEXT type elements within the application's HTML sanitization process, creating a critical security gap that allows malicious actors to execute arbitrary scripts within the application context. The vulnerability specifically targets the way SquirrelMail processes HTML content from incoming emails, where the sanitization mechanism fails to properly escape or filter certain HTML elements that should remain protected from script execution.
The technical exploitation of this vulnerability relies on the improper handling of specific HTML elements including NOEMBED, NOFRAMES, NOSCRIPT, and TEXTAREA tags. These elements are typically designed to contain raw text or prevent script execution, but SquirrelMail's sanitization logic fails to properly process them, allowing malicious script content to persist and execute when users view infected emails. The flaw occurs because the application's HTML parser does not adequately distinguish between safe and unsafe content within these elements, particularly when they contain embedded script tags or other malicious payloads. This bypasses the intended security boundaries that should prevent script execution in email contexts, creating a direct pathway for attackers to inject and execute malicious code in the victim's browser session.
From an operational impact perspective, this vulnerability enables attackers to perform a wide range of malicious activities including session hijacking, credential theft, redirection to malicious sites, and data exfiltration. When users open infected emails containing crafted HTML content, the malicious scripts execute within the SquirrelMail application context, potentially compromising user accounts and exposing sensitive email communications. The vulnerability affects not only individual user sessions but also organizational email security, as it allows attackers to establish persistent access to email systems through compromised user accounts. This represents a significant risk in enterprise environments where SquirrelMail serves as a primary email client and users regularly access sensitive business communications.
The mitigation strategies for CVE-2019-12970 involve immediate patching of affected SquirrelMail installations to versions that properly handle RCDATA and RAWTEXT elements. Organizations should implement comprehensive email filtering solutions that sanitize HTML content before delivery, including disabling or restricting the use of potentially dangerous HTML elements in email communications. Network-level protections such as web application firewalls can provide additional layers of defense by monitoring for suspicious HTML patterns and blocking known malicious payloads. Users should be educated about the risks of opening emails from untrusted sources and the importance of avoiding interaction with suspicious email content. Security teams should also consider implementing strict content security policies and monitoring for unusual script execution patterns within email client environments. This vulnerability aligns with CWE-79 Cross-site Scripting and follows ATT&CK techniques related to client-side attacks and credential access through web-based exploitation methods. Organizations should conduct thorough security assessments to identify all affected systems and ensure complete remediation across their email infrastructure.