CVE-2022-29970
📋 TL;DR
This CVE describes a path traversal vulnerability in Sinatra web framework versions before 2.2.0. It allows attackers to bypass directory restrictions and access files outside the intended public directory when serving static files. This affects any application using vulnerable Sinatra versions with static file serving enabled.
💻 Affected Systems
- Sinatra
📦 What is this software?
Sinatra by Sinatrarb
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read sensitive files like configuration files, source code, or credentials stored outside the public directory, potentially leading to complete system compromise.
Likely Case
Unauthorized file disclosure of sensitive application files, configuration data, or other files accessible to the web server process.
If Mitigated
Limited impact if proper file permissions restrict web server access to sensitive directories and files.
🎯 Exploit Status
The vulnerability is straightforward to exploit by crafting malicious URLs with path traversal sequences.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.2.0 and later
Vendor Advisory: https://github.com/sinatra/sinatra/pull/1683/commits/462c3ca1db53ed3cfc394cf5948e9c948ad1c10e
Restart Required: Yes
Instructions:
1. Update Sinatra gem to version 2.2.0 or later using 'gem update sinatra'. 2. Restart your Sinatra application. 3. Verify the update with 'gem list sinatra'.
🔧 Temporary Workarounds
Disable static file serving
allDisable Sinatra's built-in static file serving and use a reverse proxy like nginx or Apache to serve static files
set :static, false in your Sinatra configuration
Implement custom static file handler
allReplace Sinatra's static file serving with a custom handler that validates paths
🧯 If You Can't Patch
- Implement strict file system permissions to limit web server process access to sensitive directories
- Use web application firewall (WAF) rules to block path traversal patterns in URLs
🔍 How to Verify
Check if Vulnerable:
Check your Gemfile.lock or run 'gem list sinatra' to see if version is below 2.2.0Check Version:
gem list sinatra | grep sinatraVerify Fix Applied:
After updating, verify version is 2.2.0 or higher with 'gem list sinatra' and test that path traversal attempts are blocked📡 Detection & Monitoring
Log Indicators:
- HTTP requests containing '../' sequences or attempts to access files outside expected paths
- Unusual file access patterns in web server logs
Network Indicators:
- HTTP requests with path traversal sequences in URLs
- Responses containing file contents that shouldn't be publicly accessible
SIEM Query:
web_access_logs WHERE url CONTAINS '../' OR url CONTAINS '..%2F' OR url CONTAINS '%2e%2e%2f'🔗 References
- https://github.com/sinatra/sinatra/pull/1683/commits/462c3ca1db53ed3cfc394cf5948e9c948ad1c10e
- https://lists.debian.org/debian-lts-announce/2022/10/msg00034.html
- https://github.com/sinatra/sinatra/pull/1683/commits/462c3ca1db53ed3cfc394cf5948e9c948ad1c10e
- https://lists.debian.org/debian-lts-announce/2022/10/msg00034.html
- https://lists.debian.org/debian-lts-announce/2024/09/msg00020.html
