CVE-2018-18631 in Zimbra Collaboration Suite
Summary
by MITRE
mailboxd component in Synacor Zimbra Collaboration Suite 8.6, 8.7 before 8.7.11 Patch 7, and 8.8 before 8.8.10 Patch 2 has Persistent XSS.
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Analysis
by VulDB Data Team • 09/25/2023
The vulnerability identified as CVE-2018-18631 represents a critical persistent cross-site scripting flaw within the mailboxd component of Synacor Zimbra Collaboration Suite across multiple versions including 8.6, 8.7 before 8.7.11 Patch 7, and 8.8 before 8.8.10 Patch 2. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically classified as persistent XSS where malicious scripts are stored on the server and executed whenever users access affected pages. The mailboxd component serves as a core element responsible for email processing and storage within the Zimbra platform, making this vulnerability particularly dangerous as it can affect email content processing and user interactions with the email system.
The technical exploitation of this vulnerability occurs when unauthenticated or authenticated users can inject malicious JavaScript code through input fields or parameters that are then stored in the server's database and subsequently executed in the context of other users' browsers. This persistent nature means that the malicious payload remains active until manually removed from the server, potentially affecting all users who access the compromised email content. The vulnerability is particularly concerning because it can be leveraged to steal user sessions, perform unauthorized actions on behalf of victims, or redirect users to malicious websites, making it a prime target for attackers seeking to establish persistent access to email systems.
The operational impact of this vulnerability extends beyond simple script execution as it can compromise the integrity of email communications and potentially lead to broader security breaches within organizations using Zimbra Collaboration Suite. Attackers could use this vulnerability to access sensitive email content, steal authentication tokens, or escalate privileges within the email environment. The persistent nature of the vulnerability means that once exploited, the malicious code continues to affect users until the system is properly patched and the malicious content is removed from the server database. This vulnerability directly aligns with ATT&CK technique T1531 for Account Access Removal and T1059.007 for Command and Scripting Interpreter, as it enables attackers to execute malicious scripts within user contexts.
Organizations utilizing affected versions of Zimbra Collaboration Suite should prioritize immediate patching to address this vulnerability, as the persistent nature of the XSS flaw makes it particularly dangerous for long-term security exposure. The recommended mitigation strategy involves applying the vendor-provided security patches for Zimbra versions 8.7.11 Patch 7 and 8.8.10 Patch 2, which contain fixes specifically addressing the input validation issues that allow the malicious script injection. Additionally, network administrators should implement proper input sanitization measures and consider implementing web application firewalls to detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches in enterprise email systems, as the persistence of XSS flaws can lead to prolonged compromise of email environments and potential data breaches. Security teams should also conduct thorough assessments of email content and user sessions to identify any potential exploitation that may have occurred prior to patching, as the persistent nature of the vulnerability means that malicious scripts could have been active for extended periods.