CVE-2020-8035 in Groupware Webmail Edition
Summary
by MITRE
The image view functionality in Horde Groupware Webmail Edition before 5.2.22 is affected by a stored Cross-Site Scripting (XSS) vulnerability via an SVG image upload containing a JavaScript payload. An attacker can obtain access to a victim's webmail account by making them visit a malicious URL.
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Analysis
by VulDB Data Team • 10/18/2020
The vulnerability identified as CVE-2020-8035 represents a critical stored cross-site scripting flaw within Horde Groupware Webmail Edition versions prior to 5.2.22. This security weakness specifically targets the image view functionality, creating an attack vector that allows malicious actors to execute arbitrary JavaScript code within the context of a victim's browser session. The vulnerability arises from insufficient input validation and sanitization mechanisms when processing SVG image uploads, which are commonly used for displaying graphical content within webmail interfaces. The attack scenario involves an attacker uploading a specially crafted SVG file containing embedded JavaScript payloads that persist within the application's storage system, making the malicious code executable whenever legitimate users view the affected image.
The technical exploitation of this vulnerability follows a well-established XSS attack pattern where the SVG file serves as a carrier for malicious script execution. When a victim accesses their webmail account and views an email containing the compromised SVG image, the embedded JavaScript code executes within the victim's browser session, potentially compromising the user's authentication context and access privileges. This stored XSS vulnerability operates at the application layer, affecting the webmail client's rendering engine and exposing users to session hijacking, credential theft, and other malicious activities that can be performed within the scope of the victim's privileges. The vulnerability is particularly dangerous because it leverages the trusted image viewing functionality to deliver payloads that bypass traditional browser security mechanisms.
The operational impact of CVE-2020-8035 extends beyond simple script execution, as it provides attackers with the capability to fully compromise user sessions within the Horde Groupware environment. Attackers can leverage this vulnerability to access sensitive email communications, view personal information, send emails on behalf of victims, and potentially escalate privileges within the application. The stored nature of the vulnerability means that once the malicious SVG is uploaded and processed by the vulnerable system, it remains persistent and continues to affect all users who encounter the compromised content. This characteristic aligns with CWE-79, which categorizes cross-site scripting vulnerabilities as weaknesses in input validation and output encoding, and demonstrates how improper sanitization of user-supplied content can create persistent attack surfaces. The vulnerability also maps to ATT&CK technique T1059.007, which covers JavaScript and VBScript execution through webmail interfaces, emphasizing the operational security implications for email-based attack vectors.
Organizations utilizing Horde Groupware Webmail Edition must implement immediate mitigation strategies to address this vulnerability. The primary recommendation involves upgrading to version 5.2.22 or later, which includes proper input validation and sanitization measures for SVG file processing. Additionally, administrators should implement strict content filtering policies that prevent the upload of potentially malicious SVG files, including MIME type validation and file content inspection. Network-level protections such as web application firewalls can provide additional defense-in-depth measures, though the most effective solution remains the application of the vendor-provided security patch. Security monitoring should include detection of suspicious SVG file uploads and unusual user behavior patterns that may indicate successful exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date security practices and the critical need for robust input validation mechanisms in web applications that handle user-generated content, particularly within email and document management systems where the attack surface can be extensive and the potential for credential compromise significant.