CVE-2017-7188 in Zurmo
Summary
by MITRE
Zurmo 3.1.1 Stable allows a Cross-Site Scripting (XSS) attack with a base64-encoded SCRIPT element within a data: URL in the returnUrl parameter to default/toggleCollapse.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2017-7188 resides within Zurmo 3.1.1 Stable, a web application framework that suffered from a critical cross-site scripting flaw in its handling of the returnUrl parameter. This vulnerability specifically manifests when the application processes a base64-encoded script element embedded within a data: URL format, which is passed through the default/toggleCollapse endpoint. The flaw represents a classic server-side input validation failure that permits malicious actors to inject arbitrary JavaScript code into the application's response, potentially compromising user sessions and data integrity.
The technical exploitation of this vulnerability occurs through manipulation of the returnUrl parameter, where an attacker can craft a malicious URL containing a data: URL scheme with base64-encoded script content. When the application processes this parameter without proper sanitization or validation, it executes the embedded script within the context of the victim's browser session. This behavior stems from inadequate input filtering mechanisms that fail to properly decode and validate the base64-encoded content before incorporating it into the application's response. The vulnerability directly maps to CWE-79, which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding, and aligns with ATT&CK technique T1203 for exploitation of web application vulnerabilities.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform session hijacking, deface web applications, steal sensitive user information, and potentially escalate privileges within the application. Users who interact with the vulnerable application may unknowingly execute malicious code that can capture their credentials, redirect them to phishing sites, or establish persistent backdoors. The attack vector is particularly concerning because it leverages the legitimate data: URL scheme, making it more difficult to detect through standard security monitoring systems and potentially bypassing certain security controls that might not account for base64-encoded content within URL parameters.
Mitigation strategies for CVE-2017-7188 require immediate implementation of comprehensive input validation and output encoding mechanisms. Organizations should ensure that all user-supplied input, particularly URL parameters, undergoes strict sanitization before processing, with special attention to base64-encoded content within data: URLs. The application should implement proper URL validation that rejects or properly encodes any content containing executable script elements. Additionally, security headers such as Content Security Policy should be enforced to prevent execution of unauthorized scripts. Regular security audits and input validation testing should be conducted to identify similar vulnerabilities in the application's codebase. This vulnerability highlights the critical importance of implementing defense-in-depth strategies and following secure coding practices that prevent the execution of untrusted code within web applications.