CVE-2015-6942 in Coremail
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Coremail XT3.0 allows remote attackers to inject arbitrary web script or HTML via a hyperlink in a document attachment.
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Analysis
by VulDB Data Team • 11/11/2019
The CVE-2015-6942 vulnerability represents a critical cross-site scripting flaw discovered in Coremail XT3.0 email server software, which fundamentally undermines the security posture of organizations relying on this platform for email communications. This vulnerability specifically affects the handling of document attachments within the email system, creating a dangerous attack vector where malicious actors can exploit the system through seemingly benign email attachments. The flaw resides in the application's insufficient input validation and output encoding mechanisms, allowing attackers to craft malicious hyperlinks within document files that execute arbitrary JavaScript code when opened by unsuspecting users. The vulnerability is particularly concerning because email systems serve as primary attack surfaces for organizations, making this flaw a significant threat to enterprise security infrastructure.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied data within the email attachment processing pipeline. When users open document attachments that contain malicious hyperlinks, the Coremail XT3.0 system fails to properly escape or validate the hyperlink content before rendering it within the web interface. This creates an environment where attacker-controlled content can be executed in the context of the victim's browser session, bypassing standard security controls. The vulnerability maps directly to CWE-79, which defines Cross-Site Scripting as a condition where untrusted data is sent to a web browser without proper validation or escaping, allowing malicious scripts to be executed. The flaw operates at the application layer and specifically affects the web-based administration and user interfaces of the Coremail system, making it accessible to remote attackers without requiring local system access or elevated privileges.
The operational impact of this vulnerability extends far beyond simple data theft, as it enables attackers to perform a wide range of malicious activities through compromised user sessions. An attacker could leverage this vulnerability to steal session cookies, redirect users to phishing sites, inject malicious content into email conversations, or even escalate privileges within the email system itself. The attack surface is particularly broad since email is used for critical business communications, making it an ideal vector for social engineering attacks and credential theft. Organizations using Coremail XT3.0 face significant risk of data breaches, unauthorized access to sensitive communications, and potential compromise of their entire email infrastructure. The vulnerability also aligns with ATT&CK technique T1566, which describes social engineering tactics using malicious attachments, making it a prime example of how email-based attacks can bypass traditional network security controls.
Mitigation strategies for CVE-2015-6942 should focus on immediate patching of the Coremail XT3.0 system to address the input validation deficiencies. Organizations should implement comprehensive content filtering and sandboxing mechanisms for email attachments, particularly those containing document formats that may embed hyperlinks. Network administrators should consider implementing web application firewalls to detect and block malicious script execution patterns, while also establishing strict email hygiene policies that limit the execution of potentially dangerous content. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other email systems and web applications. The vulnerability highlights the importance of secure coding practices and input validation, particularly in applications that process user-generated content, and serves as a reminder of the critical need for regular security updates and vulnerability management programs. Organizations should also consider implementing email encryption and digital signatures to provide additional layers of protection beyond the basic security controls.