CVE-2020-29596
📋 TL;DR
CVE-2020-29596 is a buffer overflow vulnerability in MiniWeb HTTP server 0.8.19 that allows remote attackers to crash the server via a specially crafted POST request with an overly long parameter name. This affects anyone running the vulnerable version of MiniWeb HTTP server, potentially causing denial of service. The vulnerability stems from improper bounds checking when processing HTTP POST requests.
💻 Affected Systems
- MiniWeb HTTP Server
📦 What is this software?
Miniweb Http Server by Miniweb Http Server Project
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attackers could cause persistent denial of service by repeatedly crashing the web server, potentially leading to complete service unavailability.
Likely Case
Attackers will exploit this to cause temporary service disruption by crashing the web server process, requiring manual restart to restore service.
If Mitigated
With proper network segmentation and access controls, the impact is limited to denial of service only, with no data compromise or privilege escalation.
🎯 Exploit Status
Public exploit code is available and trivial to execute. The vulnerability requires no authentication and can be exploited with a single HTTP request.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://sourceforge.net/projects/miniweb/files/miniweb/
Restart Required: No
Instructions:
No official patch exists. The only secure remediation is to upgrade to a different HTTP server software as MiniWeb development appears abandoned.
🔧 Temporary Workarounds
Network Filtering
allImplement network filtering to block or limit POST requests with unusually long parameter names
Web Application Firewall
allDeploy WAF rules to detect and block POST requests with parameter names exceeding reasonable length
🧯 If You Can't Patch
- Replace MiniWeb with a maintained HTTP server like Apache, Nginx, or Lighttpd
- Implement strict network segmentation to limit access to MiniWeb instances
🔍 How to Verify
Check if Vulnerable:
Check if MiniWeb version 0.8.19 is running by examining process information or checking the server bannerCheck Version:
Check process name or server response headers for 'MiniWeb/0.8.19'Verify Fix Applied:
Verify that MiniWeb has been replaced with alternative HTTP server software📡 Detection & Monitoring
Log Indicators:
- Server crash logs
- Abnormal process termination
- POST requests with very long parameter names in access logs
Network Indicators:
- HTTP POST requests with parameter names exceeding 1000 characters
- Multiple connection attempts followed by service unavailability
SIEM Query:
source="web_server" AND (event="crash" OR event="terminated") AND process="miniweb"🔗 References
- https://packetstormsecurity.com/files/160470/MiniWeb-HTTP-Server-0.8.19-Buffer-Overflow.html
- https://securityforeveryone.com/blog/miniweb-http-server-vulnerability-0-day-cve-2020-29596
- https://sourceforge.net/projects/miniweb/files/miniweb/0.8/
- https://www.exploit-db.com/exploits/49247
- https://packetstormsecurity.com/files/160470/MiniWeb-HTTP-Server-0.8.19-Buffer-Overflow.html
- https://securityforeveryone.com/blog/miniweb-http-server-vulnerability-0-day-cve-2020-29596
- https://sourceforge.net/projects/miniweb/files/miniweb/0.8/
- https://www.exploit-db.com/exploits/49247
