CVE-2020-9743 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 an HTML injection vulnerability in the content editor component that allows unauthenticated users to craft an HTTP request that includes arbitrary HTML code in a parameter value. An attacker could then use the malicious GET request to lure victims to perform unsafe actions in the page (ex. phishing).
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Analysis
by VulDB Data Team • 11/13/2020
The vulnerability CVE-2020-9743 represents a critical HTML injection flaw within Adobe Experience Manager (AEM) content editor components affecting multiple version ranges including AEM 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. This vulnerability stems from insufficient input validation and output encoding mechanisms within the AEM content editor functionality, specifically when processing parameter values in HTTP requests. The flaw exists in the way the system handles user-supplied data that gets rendered within the content editor interface without proper sanitization or encoding, creating an avenue for malicious HTML code injection.
The technical exploitation of this vulnerability occurs through crafted HTTP GET requests that include arbitrary HTML code within parameter values. When these requests are processed by the vulnerable AEM components, the malicious code gets embedded into the page content and subsequently rendered to unsuspecting users who interact with the affected pages. This creates a persistent cross-site scripting (XSS) vector where attackers can inject malicious scripts that execute in the context of the victim's browser session. The vulnerability is particularly dangerous because it operates without authentication requirements, allowing any remote user to exploit it. The ATT&CK framework categorizes this under technique T1059.001 for command and scripting interpreter, specifically through web shell execution and T1566 for credential harvesting via phishing attacks.
The operational impact of CVE-2020-9743 extends beyond simple XSS exploitation to enable sophisticated social engineering campaigns and credential theft operations. Attackers can craft malicious links that, when clicked by victims, perform unauthorized actions such as redirecting users to phishing pages, stealing session cookies, or executing malicious JavaScript code that can harvest user credentials. The vulnerability effectively undermines the security boundaries of AEM installations, as it allows attackers to manipulate content that users trust and interact with regularly. This makes it particularly dangerous in enterprise environments where AEM is used for content management, digital marketing, and customer-facing applications where user trust is paramount. The CWE-79 classification for Cross-site Scripting (XSS) accurately describes this vulnerability's nature and impact on web application security.
Mitigation strategies for CVE-2020-9743 require immediate implementation of several defensive measures including upgrading to patched versions of AEM where available, implementing proper input validation and output encoding mechanisms, and deploying web application firewalls to filter malicious requests. Organizations should also consider implementing Content Security Policy (CSP) headers to limit the execution of inline scripts and restrict the sources from which scripts can be loaded. The vulnerability highlights the importance of secure coding practices in web applications and the necessity of proper parameter sanitization. Security teams should conduct thorough vulnerability assessments of all AEM installations and implement monitoring solutions to detect potential exploitation attempts. Additionally, user education and awareness programs should be enhanced to help identify and avoid suspicious links that may exploit this vulnerability. The remediation process should include comprehensive testing to ensure that the patch or mitigation does not introduce regressions in legitimate functionality while maintaining the security posture of the AEM environment.