CVE-2022-31533
📋 TL;DR
This vulnerability allows attackers to read arbitrary files on the server through absolute path traversal in the decentraminds/umbral repository. It affects any system running this software with the vulnerable Flask send_file implementation. Attackers can access sensitive files like configuration files, passwords, or source code.
💻 Affected Systems
- decentraminds/umbral
📦 What is this software?
Umbral by Umbral Project
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise through reading sensitive files like SSH keys, database credentials, or configuration files leading to data breach and system takeover.
Likely Case
Unauthorized access to sensitive files containing application secrets, user data, or system information that could enable further attacks.
If Mitigated
Limited impact with proper file system permissions, but still potential information disclosure from accessible files.
🎯 Exploit Status
Path traversal vulnerabilities are commonly exploited and require minimal technical skill.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2020-01-15
Vendor Advisory: https://github.com/github/securitylab/issues/669
Restart Required: Yes
Instructions:
1. Update to latest version of decentraminds/umbral repository
2. Verify the Flask send_file function is properly sanitizing file paths
3. Restart the application service
🔧 Temporary Workarounds
Input Validation Middleware
allAdd middleware to validate and sanitize file path inputs before they reach send_file function
# Python Flask middleware example
from flask import request, abort
import os
@app.before_request
def validate_paths():
if 'file' in request.args:
requested_path = request.args.get('file')
if os.path.isabs(requested_path) or '..' in requested_path:
abort(400)
File System Restrictions
linuxRun application with restricted file system permissions and jail/chroot environment
# Run with minimal privileges
sudo -u nobody python app.py
# Use chroot or container isolation
docker run --read-only -v /app:/app:ro your-image
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block path traversal patterns
- Restrict network access to only trusted sources using firewall rules
🔍 How to Verify
Check if Vulnerable:
Test if the application allows accessing files using absolute paths or directory traversal sequences (e.g., /etc/passwd or ../../etc/passwd)Check Version:
Check repository commit date or version metadata; vulnerable if from 2020-01-15 or earlierVerify Fix Applied:
Attempt the same path traversal attacks after patching; they should return 400/403 errors instead of file contents📡 Detection & Monitoring
Log Indicators:
- HTTP 200 responses for requests containing path traversal patterns
- Unusual file access patterns in application logs
- Requests for known sensitive files like /etc/passwd, /etc/shadow
Network Indicators:
- HTTP requests with ../ sequences or absolute paths in parameters
- Unusual file downloads from the application
SIEM Query:
source="web_logs" AND (uri="*../*" OR uri="*/etc/*" OR uri="*/root/*") AND response="200"