CVE-2020-13565 in phpGACL
Summary
by MITRE • 02/11/2021
An open redirect vulnerability exists in the return_page redirection functionality of phpGACL 3.3.7, OpenEMR 5.0.2 and OpenEMR development version 6.0.0 (commit babec93f600ff1394f91ccd512bcad85832eb6ce). A specially crafted HTTP request can redirect users to an arbitrary URL. An attacker can provide a crafted URL to trigger this vulnerability.
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Analysis
by VulDB Data Team • 02/27/2021
The vulnerability identified as CVE-2020-13565 represents a critical open redirect flaw within the phpGACL 3.3.7 framework and its integration with OpenEMR versions 5.0.2 and 6.0.0 development builds. This security weakness resides in the return_page redirection mechanism that is commonly employed in web applications for user navigation after authentication or form submissions. The flaw allows malicious actors to manipulate the redirection behavior by crafting specially formatted HTTP requests that can redirect users to arbitrary external URLs, potentially leading to phishing attacks or malicious payload delivery.
This vulnerability maps directly to CWE-601, which specifically addresses open redirect vulnerabilities where web applications redirect users to untrusted domains without proper validation. The technical implementation of this flaw occurs when the application fails to validate or sanitize the redirect parameter before processing the redirection logic. The affected systems process user-supplied input through the return_page parameter without adequate sanitization measures, creating a pathway for attackers to inject malicious URLs that will be executed during the subsequent redirect operation.
The operational impact of this vulnerability extends beyond simple redirection manipulation and creates significant security risks for organizations utilizing affected OpenEMR installations. Attackers can leverage this weakness to craft deceptive URLs that appear legitimate to users, potentially leading to credential theft, malware distribution, or further exploitation of the targeted system. The vulnerability is particularly dangerous in healthcare environments where OpenEMR systems store sensitive patient data, as it could enable attackers to bypass security controls and gain unauthorized access to protected health information. The open redirect condition creates a trust relationship manipulation scenario where users might be tricked into believing they are navigating within a trusted domain while actually being redirected to malicious external sites.
Mitigation strategies for CVE-2020-13565 should focus on implementing proper input validation and sanitization of redirect parameters within the application code. Security measures must include validating redirect URLs against a predefined whitelist of trusted domains, implementing strict URL format validation, and ensuring that all redirection logic incorporates proper security checks before executing any redirect operations. Organizations should also consider implementing web application firewalls with rule sets specifically designed to detect and block malicious redirect attempts. The remediation process requires thorough code review of the return_page functionality, implementation of proper parameter validation, and comprehensive testing to ensure that only legitimate internal redirects are processed while blocking external malicious URLs. Additionally, security awareness training for system administrators should emphasize the importance of keeping affected systems updated with patched versions and monitoring for suspicious redirect patterns in web application logs.