CVE-2020-9740
📋 TL;DR
This stored cross-site scripting (XSS) vulnerability in Adobe Experience Manager allows users with 'Author' privileges to inject malicious scripts into Design Importer fields. When victims view pages containing these scripts, the code executes in their browsers, potentially compromising their sessions or systems. The vulnerability affects multiple AEM versions up to 6.5.5.0, 6.4.8.1, 6.3.3.8, and 6.2 SP1-CFP20.
💻 Affected Systems
- Adobe Experience Manager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers with author privileges could steal administrator credentials, perform actions as authenticated users, deface websites, or redirect users to malicious sites, potentially leading to complete system compromise.
Likely Case
Attackers with author access inject malicious scripts that steal session cookies or perform unauthorized actions when administrators or other users view affected pages.
If Mitigated
With proper input validation and output encoding, the risk is limited to users with author privileges misusing their legitimate access.
🎯 Exploit Status
Requires author-level access; exploitation is straightforward once access is obtained
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AEM 6.5.6.0, 6.4.9.0, 6.3.3.9, 6.2 SP1-CFP21
Vendor Advisory: https://helpx.adobe.com/security/products/experience-manager/apsb20-56.html
Restart Required: Yes
Instructions:
1. Download appropriate AEM service pack or cumulative fix pack from Adobe. 2. Backup your AEM instance. 3. Apply the patch following Adobe's installation instructions. 4. Restart AEM services. 5. Verify the patch was applied successfully.
🔧 Temporary Workarounds
Restrict Design Importer Access
allLimit access to Design Importer functionality to trusted administrators only
Modify AEM permissions to remove 'Author' access to /libs/cq/gui/components/authoring/dialog/dialogfieldset/designimporter
Implement Content Security Policy
allAdd CSP headers to prevent script execution from untrusted sources
Add 'Content-Security-Policy' header with appropriate directives to AEM dispatcher or web server configuration
🧯 If You Can't Patch
- Implement strict input validation and output encoding for all Design Importer fields
- Monitor and audit all author-level user activities, especially Design Importer usage
🔍 How to Verify
Check if Vulnerable:
Check AEM version via OSGi console or CRXDE; if version is 6.5.5.0 or below, 6.4.8.1 or below, 6.3.3.8 or below, or 6.2 SP1-CFP20 or below, the system is vulnerableCheck Version:
curl -u admin:password http://localhost:4502/system/console/status-productinfo | grep 'Adobe Experience Manager'Verify Fix Applied:
Verify AEM version is 6.5.6.0 or higher, 6.4.9.0 or higher, 6.3.3.9 or higher, or 6.2 SP1-CFP21 or higher📡 Detection & Monitoring
Log Indicators:
- Unusual Design Importer activity by author users
- Multiple failed script injection attempts in request logs
- Suspicious JavaScript payloads in content updates
Network Indicators:
- Unexpected JavaScript execution in browser responses
- Suspicious outbound connections from user browsers after viewing AEM pages
SIEM Query:
source="aem-access.log" AND ("designimporter" OR "script" OR "javascript") AND status=200