CVE-2006-3108 in Email Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in EmailArchitect Email Server 6.1 allows remote attackers to inject arbitrary Javascript via an HTML div tag with a carriage return between the onmouseover attribute and its value, which bypasses the mail filter.
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Analysis
by VulDB Data Team • 09/18/2017
The vulnerability described in CVE-2006-3108 represents a critical cross-site scripting flaw within the EmailArchitect Email Server version 6.1 that enables remote attackers to execute malicious javascript code through carefully crafted email content. This particular XSS vulnerability exploits a specific bypass technique involving HTML div tags with carriage returns between the onmouseover attribute and its assigned value, allowing attackers to circumvent the server's mail filtering mechanisms. The flaw resides in the server's insufficient input validation and sanitization processes, which fail to properly handle malformed HTML attributes that could be used for malicious payload injection.
The technical implementation of this vulnerability demonstrates a sophisticated bypass method that leverages the way the email server processes and filters HTML content. When an attacker crafts an email containing an HTML div tag with a carriage return character inserted between the onmouseover attribute declaration and its value, the server's filtering logic fails to recognize this as a potential threat. This specific formatting technique exploits a gap in the regular expression patterns or HTML parsing routines used by the email server's security filters. The carriage return character acts as a delimiter that the filter does not properly account for during validation, allowing the malicious javascript code to remain embedded in the email content and subsequently executed when the email is viewed by a victim.
From an operational impact perspective, this vulnerability creates a significant security risk for organizations relying on the EmailArchitect Email Server 6.1, as it enables attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. When users receive emails containing the crafted malicious content, any interaction with the email—such as hovering over the div element—can trigger the execution of the embedded javascript code. This allows attackers to establish persistent access to user sessions, steal authentication tokens, redirect users to malicious websites, or even install malware on affected systems. The vulnerability is particularly dangerous because it bypasses the server's built-in security measures, making it appear as legitimate content to the filtering system while simultaneously creating a backdoor for malicious activity.
The security implications of this vulnerability align with CWE-79, which specifically addresses cross-site scripting flaws in web applications and email systems. This classification indicates that the vulnerability represents a classic input validation issue where untrusted data enters the application without proper sanitization. Additionally, from an attacker perspective, this vulnerability maps to several ATT&CK techniques including T1566 for initial access through spearphishing and T1059 for command and control through script injection. Organizations should implement immediate mitigations including updating to the latest version of the EmailArchitect Email Server that addresses this specific bypass technique, implementing more robust HTML sanitization filters, and deploying additional email security layers such as content inspection appliances or advanced threat protection systems. Network segmentation and user education regarding suspicious email content should also be considered as part of a comprehensive defense-in-depth strategy to prevent exploitation of this vulnerability.