CVE-2017-11666 in Kopano WebApp
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in js/ViewerPanel.js in the file previewer plugin in Kopano WebApp versions 3.3.0 and earlier allows remote attackers to inject arbitrary web script or HTML via a specially crafted previewable file.
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Analysis
by VulDB Data Team • 11/01/2019
The vulnerability identified as CVE-2017-11666 represents a critical cross-site scripting flaw within the Kopano WebApp file previewer plugin, specifically affecting versions 3.3.0 and earlier. This vulnerability resides in the js/ViewerPanel.js file which handles the rendering of previewable files within the web application interface. The flaw enables remote attackers to execute malicious web scripts or HTML code through the manipulation of previewable files, creating a significant security risk for organizations relying on this collaboration platform. The vulnerability is particularly concerning as it operates at the user interface level where file previews are displayed, making it accessible to any user who might inadvertently open a maliciously crafted file within the previewer functionality.
The technical implementation of this XSS vulnerability stems from insufficient input validation and output encoding within the ViewerPanel.js component. When the web application processes previewable files, it fails to properly sanitize or escape user-supplied content that may be embedded within these files. This inadequate sanitization allows attackers to inject malicious payloads that execute in the context of the victim's browser session. The vulnerability manifests when the application renders file previews without sufficient security controls to prevent script execution, effectively creating a vector for persistent cross-site scripting attacks that can compromise user sessions and potentially escalate to more severe exploits.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform session hijacking, steal sensitive information, manipulate user interfaces, and potentially gain unauthorized access to confidential data within the Kopano WebApp environment. Users who access previewable files from untrusted sources may unknowingly execute malicious code that persists in their browser sessions. This vulnerability is particularly dangerous in enterprise environments where collaboration platforms like Kopano WebApp are extensively used, as it could allow attackers to access shared documents, calendar entries, contact information, and other sensitive business data. The attack vector is easily exploitable through social engineering techniques where users are tricked into opening malicious files, making this vulnerability particularly dangerous in environments with less security awareness.
Organizations should immediately update to versions of Kopano WebApp that address this vulnerability, as the patch likely implements proper input validation and output encoding mechanisms to prevent XSS attacks. Security measures should include implementing content security policies that restrict script execution within the previewer functionality, enabling proper sanitization of file content before preview rendering, and conducting regular security assessments of web application components. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and represents a technique commonly categorized under ATT&CK tactic TA0001 (Initial Access) and technique T1190 (Exploit Public-Facing Application). Administrators should also consider implementing web application firewalls and monitoring for suspicious file preview activities to detect potential exploitation attempts. Regular security training for users to recognize phishing attempts and suspicious file attachments remains crucial in mitigating the risk associated with this vulnerability.