CVE-2017-6913 in Open-Xchange Webmail
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Open-Xchange webmail before 7.6.3-rev28 allows remote attackers to inject arbitrary web script or HTML via the event attribute in a time tag.
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Analysis
by VulDB Data Team • 03/24/2020
The CVE-2017-6913 vulnerability represents a critical cross-site scripting flaw discovered in the Open-Xchange webmail platform prior to version 7.6.3-rev28. This vulnerability resides within the application's handling of time tag event attributes, creating a pathway for remote attackers to execute malicious web scripts or HTML code within the context of other users' browsers. The vulnerability specifically targets the webmail interface's insufficient input validation and output encoding mechanisms, allowing attackers to manipulate the event attribute of time tags to inject malicious payloads that persist in the application's user interface.
The technical exploitation of this vulnerability occurs through the improper sanitization of user-supplied data within the time tag event attribute parameter. When the webmail application processes calendar events or time-related data, it fails to adequately sanitize the event attribute values before rendering them in the user interface. This insufficient validation creates an environment where attackers can inject malicious JavaScript code or HTML elements that execute when other users view the affected calendar entries. The vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically representing a stored XSS variant where the malicious payload is stored on the server and executed against multiple users.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. An attacker could craft a malicious calendar event containing JavaScript code that steals session cookies from users viewing the calendar, potentially gaining unauthorized access to user accounts. Additionally, the vulnerability could be exploited to redirect users to phishing sites, modify calendar entries, or inject malicious content that persists across multiple user sessions. The persistent nature of the stored XSS vulnerability means that once the malicious payload is injected, it continues to affect users until the calendar entry is modified or deleted, making it particularly dangerous in collaborative environments where multiple users interact with shared calendar data.
Security professionals should implement comprehensive input validation and output encoding measures to address this vulnerability, following established security frameworks such as the OWASP Top Ten and MITRE ATT&CK methodology for web application security. The mitigation strategy should include strict sanitization of all user inputs, particularly those related to calendar and time-related attributes, along with implementing Content Security Policy headers to prevent unauthorized script execution. Organizations should also consider deploying web application firewalls and monitoring for suspicious calendar event creation patterns, as the vulnerability specifically targets calendar functionality within the webmail interface. The remediation process requires updating to Open-Xchange version 7.6.3-rev28 or later, which includes proper input validation and output encoding mechanisms designed to prevent XSS injection in time tag event attributes.