CVE-2018-20239 in Application Links
Summary
by MITRE
Application Links before version 5.0.11, from version 5.1.0 before 5.2.10, from version 5.3.0 before 5.3.6, from version 5.4.0 before 5.4.12, and from version 6.0.0 before 6.0.4 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in the applinkStartingUrl parameter.
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Analysis
by VulDB Data Team • 09/11/2023
The vulnerability identified as CVE-2018-20239 represents a critical cross site scripting flaw affecting the Application Links component across multiple version ranges. This vulnerability exists within the parameter validation mechanisms of the applinkStartingUrl component, which fails to properly sanitize user input before processing. The flaw allows remote attackers to inject malicious HTML or JavaScript code through carefully crafted input strings that are then executed in the context of other users' browsers. This type of vulnerability falls under the Common Weakness Enumeration category CWE-79, which specifically addresses Cross-Site Scripting vulnerabilities. The vulnerability affects a wide range of versions including 5.0.11 and below, 5.1.0 through 5.2.9, 5.3.0 through 5.3.5, 5.4.0 through 5.4.11, and 6.0.0 through 6.0.3, indicating a prolonged period during which the security flaw was present in the software ecosystem.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input containing HTML or JavaScript code and injects it into the applinkStartingUrl parameter. When the application processes this parameter without proper sanitization or encoding, the injected code becomes part of the web page served to legitimate users. This creates a persistent threat where any user who accesses a page containing the vulnerable parameter becomes a potential victim of the XSS attack. The impact extends beyond simple script execution to potentially enabling session hijacking, credential theft, and redirection to malicious websites. The vulnerability operates at the application layer and requires no special privileges to exploit, making it particularly dangerous in environments where users may interact with untrusted content.
From an operational perspective, this vulnerability creates significant security risks for organizations utilizing affected versions of the Application Links component. The remote nature of the attack means that threat actors can exploit the vulnerability from anywhere on the internet without requiring physical access to the target network. Successful exploitation could result in unauthorized access to user sessions, data exfiltration, and potential compromise of the entire application environment. The vulnerability's presence across multiple major version releases indicates a systemic issue in the input validation approach used by the application developers. Organizations may experience cascading effects where a single compromised user session can lead to broader access within the application ecosystem, particularly if the affected component is used for authentication or authorization processes.
Mitigation strategies for CVE-2018-20239 should prioritize immediate patching of affected versions to the latest available releases that contain the necessary security fixes. Organizations should implement comprehensive input validation and output encoding mechanisms to prevent similar vulnerabilities from occurring in other components. The implementation of Content Security Policy headers can provide additional defense in depth against XSS attacks by restricting the sources from which scripts can be loaded. Regular security testing including dynamic application security testing and manual penetration testing should be conducted to identify and remediate similar vulnerabilities. Organizations should also consider implementing web application firewalls to detect and block suspicious input patterns. The vulnerability's classification under ATT&CK technique T1059.007 for Scripting demonstrates the importance of preventing malicious script execution at multiple layers of the security architecture. Regular security awareness training for developers should emphasize secure coding practices, particularly around parameter validation and input sanitization, to prevent future occurrences of similar vulnerabilities.