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Scan Onion Services for Security Issues
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README.md

OnionScan

The purpose of this tool is to make you a better onion service provider. You owe it to yourself and your users to ensure that attackers cannot easily exploit and deanonymize.

Go Dependencies

  • h12.me/socks - For the Tor SOCKS Proxy connection.
  • github.com/xiam/exif - For EXIF data extraction.
  • github.com/mvdan/xurls - For some URL parsing.

OS Package Dependencies

  • libexif-dev on Debian based OS
  • libexif-devel on Fedora

Installing

Install OS dependencies

  • On Debian based operating systems: sudo apt-get install libexif-dev
  • On Fedora based operating systems: sudo dnf install libexif-devel

Grab with go get

go get github.com/s-rah/onionscan

Compile/Run from git cloned source

go install github.com/s-rah/onionscan and then run the program in ./bin/onionscan.

Or, you can just do go run github.com/s-rah/onionscan.go to execute without compiling.

Running

For a simple report detailing the high, medium and low risk areas found:

./bin/onionscan blahblahblah.onion

The most interesting output comes from the verbose option:

./bin/onionscan --verbose blahblahblah.onion

There is also a JSON output, if you want to integrate with something else:

./bin/onionscan --jsonReport blahblahblah.onion

If you would like to use a proxy server listening on something other that 127.0.0.1:9050, then you can use the --torProxyAddress flag:

./bin/onionscan --torProxyAddress=127.0.0.1:9150 blahblahblah.onion

Apache mod_status Protection

This should not be news, you should not have it enabled. If you do have it enabled, attacks can:

  • Build a better fingerprint of your server, including php and other software versions.
  • Determine client IP addresses if you are co-hosting a clearnet site.
  • Determine your IP address if your setup allows.
  • Determine other sites you are co-hosting.
  • Determine how active your site is.
  • Find secret or hidden areas of your site
  • and much, much more.

Seriously, don't even run the tool, go to your site and check if you have /server-status reachable. If you do, turn it off!

Open Directories

Basic web security 101, if you leave directories open then people are going to scan them, and find interesting things - old versions of images, temp files etc.

Many sites use common structures style/, images/ etc. The tool checks for common variations, and allows the user to submit others for testing.

EXIF Tags

Whether you create them yourself or allow users to upload images, you need to ensure the metadata associated with the image is stripped.

Many, many websites still do not properly sanitise image data, leaving themselves or their users at risk of deanonymization.

Server Fingerprint

Sometimes, even without mod_status we can determine if two sites are hosted on the same infrastructure. We can use the following attributes to make this distinction:

  • Server HTTP Header
  • Technology Stack (e.g. php, jquery version etc.)
  • Website folder layout e.g. do you use /style or /css or do you use wordpress.
  • Fingerprints of images
  • GPG Versions being used.
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