CVE-2020-21124
📋 TL;DR
CVE-2020-21124 is a critical access control vulnerability in UReport 2.2.9 that allows attackers to reach the designer page without authentication, leading to arbitrary code execution. This affects all organizations using the vulnerable version of UReport for reporting functionality. Attackers can compromise the entire application server through this flaw.
💻 Affected Systems
- UReport
📦 What is this software?
Ureport by Ureport Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with remote code execution leading to data theft, ransomware deployment, or creation of persistent backdoors.
Likely Case
Attackers gain shell access to the server, install malware, exfiltrate sensitive data, and pivot to other internal systems.
If Mitigated
With proper network segmentation and access controls, impact limited to the UReport application server only.
🎯 Exploit Status
The vulnerability is straightforward to exploit - attackers simply need to access the designer page URL without authentication. Public GitHub issues demonstrate the attack path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.2.10 or later
Vendor Advisory: https://github.com/youseries/ureport/issues/484
Restart Required: Yes
Instructions:
1. Backup current UReport configuration and data. 2. Download UReport 2.2.10 or later from official repository. 3. Replace the vulnerable JAR files with patched versions. 4. Restart the application server. 5. Verify the designer page now requires proper authentication.
🔧 Temporary Workarounds
Network Access Control
linuxRestrict access to UReport endpoints using firewall rules or network segmentation.
iptables -A INPUT -p tcp --dport [UREPORT_PORT] -s [TRUSTED_NETWORK] -j ACCEPT
iptables -A INPUT -p tcp --dport [UREPORT_PORT] -j DROP
Application Firewall Rules
allBlock access to designer page endpoints using web application firewall or reverse proxy rules.
# Nginx example: location ~* /designer { deny all; }
# Apache example: <Location /designer> Require all denied </Location>
🧯 If You Can't Patch
- Immediately isolate the UReport server from internet access and restrict to necessary internal networks only.
- Implement strict authentication requirements for all UReport endpoints using a reverse proxy or application gateway.
🔍 How to Verify
Check if Vulnerable:
Attempt to access http://[ureport-server]/ureport/designer without authentication. If page loads, system is vulnerable.Check Version:
Check UReport JAR file version or application startup logs for version information.Verify Fix Applied:
Attempt same access to designer page - should receive authentication prompt or access denied error.📡 Detection & Monitoring
Log Indicators:
- Unauthenticated access to /ureport/designer endpoints
- Unusual file uploads or system command execution from UReport context
Network Indicators:
- HTTP requests to designer endpoints from untrusted sources
- Outbound connections from UReport server to suspicious destinations
SIEM Query:
source="ureport.log" AND (uri_path="/designer" OR uri_path="/ureport/designer") AND http_status=200