CVE-2020-27998
📋 TL;DR
CVE-2020-27998 is a critical vulnerability in FastReport versions before 2020.4.0, where the lack of a ScriptSecurity feature allows attackers to execute arbitrary code by exploiting script functions like GetType, DllImport, and LoadLibrary. This affects any application using vulnerable FastReport libraries for report generation, potentially leading to full system compromise.
💻 Affected Systems
- FastReport
📦 What is this software?
Fastreport by Fast Report
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution (RCE) leading to complete system takeover, data theft, or deployment of ransomware.
Likely Case
RCE enabling attackers to run malicious scripts, steal sensitive data, or pivot to other systems.
If Mitigated
Limited impact if network segmentation and least privilege are enforced, but still poses a risk of data exposure.
🎯 Exploit Status
Exploitation is straightforward due to the lack of script security controls; public proof-of-concept details are available in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2020.4.0 or later
Vendor Advisory: https://opensource.fast-report.com/2020/09/report-script-security.html
Restart Required: Yes
Instructions:
1. Identify FastReport version in use. 2. Update to version 2020.4.0 or later via package manager or manual download. 3. Restart the application or service to apply changes.
🔧 Temporary Workarounds
Disable Script Execution
allConfigure FastReport to disable or restrict script execution features if possible, though this may limit functionality.
No standard commands; configure via application settings or code modifications.
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable systems from critical networks.
- Apply strict access controls and monitor for unusual script execution or network activity.
🔍 How to Verify
Check if Vulnerable:
Check the FastReport version in your application's dependencies or configuration files; if it's below 2020.4.0, it is vulnerable.Check Version:
For .NET applications, check the FastReport.dll version via PowerShell: [System.Reflection.Assembly]::LoadFile('path\to\FastReport.dll').GetName().VersionVerify Fix Applied:
After updating, verify the version is 2020.4.0 or later and test report generation to ensure script security features are active.📡 Detection & Monitoring
Log Indicators:
- Unusual script execution logs in FastReport or application logs, such as calls to GetType or DllImport.
Network Indicators:
- Outbound connections to unknown IPs or domains from the application process.
SIEM Query:
Example: 'source="FastReport" AND (event="ScriptExecution" OR event="DllImport")'🔗 References
- https://github.com/FastReports/FastReport/compare/v2020.3.0...v2020.4.0
- https://github.com/FastReports/FastReport/pull/206
- https://opensource.fast-report.com/2020/09/report-script-security.html
- https://securitylab.github.com/advisories/GHSL-2020-143-FastReportsInc-FastReports
- https://github.com/FastReports/FastReport/compare/v2020.3.0...v2020.4.0
- https://github.com/FastReports/FastReport/pull/206
- https://opensource.fast-report.com/2020/09/report-script-security.html
- https://securitylab.github.com/advisories/GHSL-2020-143-FastReportsInc-FastReports
