CVE-2020-9740 in Experience Manager
Summary
by MITRE
AEM versions 6.5.5.0 (and below), 6.4.8.1 (and below), 6.3.3.8 (and below) and 6.2 SP1-CFP20 (and below) are affected by a stored XSS vulnerability that allows users with 'Author' privileges to store malicious scripts in fields associated with the Design Importer. These scripts may be executed in a victim’s browser when they open the page containing the vulnerable field.
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Analysis
by VulDB Data Team • 11/13/2020
The vulnerability identified as CVE-2020-9740 represents a critical stored cross-site scripting flaw within Adobe Experience Manager platforms. This security weakness affects multiple versions of AEM including 6.5.5.0 and earlier, 6.4.8.1 and earlier, 6.3.3.8 and earlier, and 6.2 SP1-CFP20 and earlier releases. The flaw specifically targets the Design Importer functionality within the authoring environment, creating a persistent threat vector that can compromise user sessions and execute malicious code within victim browsers. The vulnerability operates under the CWE-79 classification as a stored cross-site scripting attack, where malicious scripts are permanently stored and later executed during normal user interactions with the affected system.
The technical implementation of this vulnerability occurs when users with 'Author' privileges manipulate fields within the Design Importer component to inject malicious JavaScript code. This code becomes permanently stored within the AEM system's database or content repository, waiting for unsuspecting users to view pages containing these compromised fields. When victims access pages displaying the malicious content, their browsers execute the stored scripts within the context of their authenticated sessions, potentially leading to complete session hijacking, data exfiltration, or further exploitation. The attack vector leverages the trust relationship between the victim browser and the AEM application, making it particularly dangerous as it can bypass traditional security controls that rely on user behavior detection.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to manipulate user sessions and potentially escalate privileges within the AEM environment. Authors with limited permissions can leverage this flaw to gain unauthorized access to sensitive content, modify page designs, or extract confidential information from the system. The persistent nature of stored XSS means that the malicious code remains active until manually removed from the system, potentially affecting numerous users over extended periods. This vulnerability particularly impacts organizations relying on AEM for content management, as it can compromise the integrity of published content and user sessions across multiple pages and applications.
Security mitigation strategies for CVE-2020-9740 should prioritize immediate patching of affected AEM versions to the latest supported releases. Organizations must implement comprehensive input validation and output encoding mechanisms to prevent malicious script injection into design importer fields. The implementation of Content Security Policy headers can provide additional protection by restricting script execution within the browser context. Regular security audits and privilege reviews should be conducted to minimize the attack surface, ensuring that only authorized users possess the ability to modify design importer components. Network segmentation and monitoring solutions should be deployed to detect anomalous activities related to content modification. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, specifically focusing on JavaScript execution within web applications. Organizations should also consider implementing web application firewalls to detect and block suspicious payloads attempting to exploit this stored XSS vulnerability. The remediation process must include thorough testing of patched systems to ensure that security updates do not negatively impact legitimate business functionality while maintaining the integrity of the AEM content management platform.