CVE-2020-15227
📋 TL;DR
CVE-2020-15227 is a code injection vulnerability in Nette PHP framework that allows attackers to execute arbitrary code by passing specially crafted parameters to URLs. This affects all Nette applications using vulnerable versions, potentially leading to remote code execution. The vulnerability stems from improper input validation in URL parameter handling.
💻 Affected Systems
- Nette Framework
- Nette Application
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Web application compromise allowing attackers to execute arbitrary PHP code, access sensitive data, and potentially pivot to other systems.
If Mitigated
Limited impact with proper input validation and WAF rules in place, potentially reduced to denial of service or information disclosure.
🎯 Exploit Status
Exploit details are publicly available in the advisory and require minimal technical skill to implement.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.19, 2.1.13, 2.2.10, 2.3.14, 2.4.16, or 3.0.6 depending on your version line
Vendor Advisory: https://github.com/nette/application/security/advisories/GHSA-8gv3-3j7f-wg94
Restart Required: No
Instructions:
1. Identify your Nette version. 2. Update composer.json to require the patched version. 3. Run 'composer update nette/application' or 'composer update nette/nette'. 4. Test application functionality.
🔧 Temporary Workarounds
Input Validation Filter
allImplement strict input validation for all URL parameters to filter malicious payloads.
WAF Rule Implementation
allDeploy web application firewall rules to block suspicious parameter patterns.
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all user-controlled parameters
- Deploy web application firewall with rules targeting PHP code injection patterns
🔍 How to Verify
Check if Vulnerable:
Check composer.json or composer.lock for Nette version numbers below the patched versions.Check Version:
composer show nette/application --format=json | grep versionVerify Fix Applied:
Verify that Nette version in composer.lock matches or exceeds the patched version for your branch.📡 Detection & Monitoring
Log Indicators:
- Unusual URL parameters containing PHP code patterns
- Multiple failed parameter validation attempts
- Unexpected process execution from web server
Network Indicators:
- HTTP requests with suspicious parameter values containing PHP code
- Unusual outbound connections from web server
SIEM Query:
web_access_logs WHERE url_parameters CONTAINS '<?php' OR url_parameters CONTAINS 'eval(' OR url_parameters CONTAINS 'system('🔗 References
- https://github.com/nette/application/security/advisories/GHSA-8gv3-3j7f-wg94
- https://lists.debian.org/debian-lts-announce/2021/04/msg00003.html
- https://packagist.org/packages/nette/application
- https://packagist.org/packages/nette/nette
- https://github.com/nette/application/security/advisories/GHSA-8gv3-3j7f-wg94
- https://lists.debian.org/debian-lts-announce/2021/04/msg00003.html
- https://packagist.org/packages/nette/application
- https://packagist.org/packages/nette/nette
