CVE-2015-9276 in SmarterMail
Summary
by MITRE
SmarterTools SmarterMail before 13.3.5535 was vulnerable to stored XSS by bypassing the anti-XSS mechanisms. It was possible to run JavaScript code when a victim user opens or replies to the attacker's email, which contained a malicious payload. Therefore, users' passwords could be reset by using an XSS attack, as the password reset page did not need the current password.
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Analysis
by VulDB Data Team • 05/02/2020
The vulnerability identified as CVE-2015-9276 affects SmarterTools SmarterMail email server software prior to version 13.3.5535, representing a critical stored cross-site scripting flaw that bypasses built-in security mechanisms. This vulnerability resides in the email handling and rendering components of the application where user-supplied content is not properly sanitized before being stored and subsequently displayed to other users. The flaw allows attackers to inject malicious JavaScript code into email messages that can execute in the context of other users' browsers when they view or interact with the compromised emails. The security mechanism designed to prevent such attacks was successfully circumvented, creating a persistent threat vector that remains active until the malicious content is removed from the system.
The technical exploitation of this vulnerability occurs through the manipulation of email content where attackers craft malicious payloads that contain JavaScript code designed to exploit the stored XSS flaw. When victim users open or reply to emails containing the malicious payload, the JavaScript executes within their browser context, potentially allowing attackers to access session cookies, steal authentication tokens, or perform actions on behalf of the user. The vulnerability is particularly dangerous because it operates at the application layer where email content is processed and displayed, making it difficult to distinguish between legitimate and malicious content without proper input validation. This type of vulnerability maps directly to CWE-79, which defines cross-site scripting flaws where untrusted data is improperly sanitized before being rendered in web browsers.
The operational impact of this vulnerability extends beyond simple script execution to include potential account compromise and credential theft. The attack vector specifically targets the password reset functionality of the email system, which was designed to operate without requiring the current password for validation. This design flaw means that successful XSS exploitation could lead to complete account takeover scenarios where attackers can reset passwords for arbitrary user accounts. The combination of stored XSS with the password reset mechanism creates a particularly dangerous attack surface where attackers can establish persistent access to user accounts without needing to compromise authentication credentials directly. This vulnerability affects the confidentiality, integrity, and availability of the email system, potentially allowing attackers to read all emails, send messages on behalf of users, and access sensitive information stored within the email infrastructure.
Organizations using affected versions of SmarterMail should prioritize immediate remediation through the application of the vendor-provided security patch that addresses the XSS bypass mechanism and implements proper input sanitization. The mitigation strategy should include implementing proper content security policies to prevent execution of unauthorized scripts, deploying web application firewalls to detect and block malicious payloads, and conducting thorough security testing of email content processing components. Additionally, security teams should implement monitoring for suspicious email patterns and user behavior that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and the potential consequences when security controls are bypassed, highlighting the need for defense-in-depth approaches that include multiple layers of protection beyond single-point security mechanisms. This case study exemplifies how vulnerabilities in web application components can be exploited to create cascading security issues that compromise entire user authentication systems.