CVE-2017-16768 in MailPlus Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in User Policy editor in Synology MailPlus Server before 1.4.0-0415 allows remote authenticated users to inject arbitrary HTML via the name parameter.
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Analysis
by VulDB Data Team • 01/19/2023
The CVE-2017-16768 vulnerability represents a critical cross-site scripting flaw within Synology MailPlus Server's User Policy editor component. This vulnerability affects versions prior to 1.4.0-0415 and exposes the system to remote authenticated attackers who can exploit the weakness through the name parameter. The flaw resides in the server's insufficient input validation mechanisms, specifically failing to properly sanitize user-supplied data before processing it within the policy editor interface. The vulnerability demonstrates a classic XSS attack vector where malicious input can be executed in the context of a victim's browser session, potentially compromising user security and system integrity.
The technical implementation of this vulnerability stems from improper HTML escaping and input sanitization within the User Policy editor's handling of the name parameter. When authenticated users interact with the policy management interface, the server fails to adequately filter or encode special characters that could be interpreted as HTML or JavaScript code. This allows attackers who have valid authentication credentials to craft malicious payloads that get stored and subsequently executed when other users view the affected policy entries. The vulnerability operates under CWE-79 which classifies it as a cross-site scripting weakness, specifically representing a failure to sanitize input data before rendering it in web contexts. This flaw directly enables attackers to bypass security controls that would normally prevent malicious script execution within web browsers.
The operational impact of this vulnerability extends beyond simple script injection, creating potential pathways for more sophisticated attacks within the MailPlus Server environment. Remote authenticated users can leverage this weakness to execute malicious scripts that may steal session cookies, redirect users to phishing sites, or perform actions on behalf of authenticated users. The attack surface is particularly concerning because MailPlus Server typically handles sensitive email communications and user policies, making successful exploitation potentially devastating for organizations relying on the system. This vulnerability aligns with ATT&CK technique T1566 which describes social engineering tactics involving malicious payloads delivered through web interfaces. The risk is amplified by the fact that legitimate users must interact with the policy editor, increasing the likelihood of successful exploitation through targeted attacks or compromised accounts.
Organizations should prioritize immediate remediation by upgrading to Synology MailPlus Server version 1.4.0-0415 or later, which includes proper input validation and sanitization mechanisms. Additional mitigations should include implementing strict access controls and monitoring user activities within the policy editor, as well as conducting regular security assessments of web-based administrative interfaces. Network segmentation and web application firewalls can provide additional layers of defense against exploitation attempts. Security teams should also implement comprehensive logging and monitoring of policy changes to detect potential malicious activities. The vulnerability serves as a reminder of the critical importance of input validation in web applications and highlights the necessity of following secure coding practices to prevent XSS vulnerabilities in enterprise email systems.