Secret Detectors

Secret Detectors have these two major functions:

1. Given some bytes, extract possible secrets, typically using a regex.
2. Validate the secrets against the target API, typically using a HTTP client.

The purpose of Secret Detectors is to discover secrets with exceptionally high signal. High rates of false positives are not accepted.

Table of Contents

• Secret Detectors
  • Table of Contents
  • Getting Started
    • Sourcing Guidelines
    • Development Guidelines
    • Development Dependencies
    • Creating a new Secret Detector
    • Testing the Detector
  • Addendum
    • Adding Protos in Windows

Getting Started

Sourcing Guidelines

We are interested in detectors for services that meet at least one of these criteria

• host data (they store any sort of data provided)
• have paid services (having a free or trial tier is okay though)

If you think that something should be included outside of these guidelines, please let us know.

Development Guidelines

• When reasonable, favor using the net/http library to make requests instead of bringing in another library.
• Use the common.SaneHttpClient for the http.Client whenever possible.

Development Dependencies

• Go 1.17+
• Make

Adding New Token Formats to an Existing Scanner

In some instances, services will update their token format, requiring a new regex to properly detect secrets in addition to supporting the previous token format. Accommodating this can be done without adding a net-new detector. We provide a Versioner interface that can be implemented.

1. Create two new directories v1 and v2. Move the existing detector and tests into v1, and add new files to v2. Ex: <packagename>/<old_files> -> <packagename>/v1/<old_files>, <packagename>/v2/<new_files>

Note: Be sure to update the tests to reference the new secret values in GSM, or the tests will fail.

2. Implement the Versioner interface. GitHub example implementation.)

3. Add a 'version' field in ExtraData for both existing and new detector versions.

4. Update the existing detector in DefaultDetectors in /pkg/engine/defaults/defaults.go

5. Proceed from step 3 of Creating a new Secret Scanner

Creating a new Secret Detector

1. Add a new Secret Detector enum to the DetectorType list here.

2. Run make protos to update the .pb files.

3. Generate the Secret Detector

   bashCopy

   go run hack/generate/generate.go detector <DetectorType enum name>
   example: go run hack/generate/generate.go detector SampleAPI
   

4. Add the Secret Detector to TruffleHog's Default Detectors

   Add the secret scanner to the pkg/engine/defaults/defaults.go file like github.com/trufflesecurity/trufflehog/v3/pkg/detectors/<detector_name> and <detector_name>.Scanner{}

5. Complete the Secret Detector.

   The previous step templated a boilerplate + some example code as a package in the pkg/detectors folder for you to work on. The Secret Detector can be completed with these general steps:

   1. Update the pattern regex and keywords. Try iterating with regex101.com.
   2. Update the verifier code to use a non-destructive API call that can determine whether the secret is valid or not.
      • Make sure you understand verification indeterminacy.
   3. Create a test for the detector.
   4. Add your new detector to DefaultDetectors in /pkg/engine/defaults/defaults.go.
   5. Create a pull request for review.

Testing the Detector

To ensure the quality of your PR, make sure your tests are passing with verified credentials.

1. Create a file called .env with this env file format:

   bashCopy

   SECRET_TYPE_ONE=value
   SECRET_TYPE_ONE_INACTIVE=v@lue
   

2. Export the TEST_SECRET_FILE variable, pointing to the env file:

   bashCopy

   export TEST_SECRET_FILE=".env"
   

   The .env file should be in the new detector's directory like this:

   Copy

   ├── tailscale
   │   ├── .env
   │   ├── tailscale.go
   │   └── tailscale_test.go
   

   Now that a .env file is present, the test file can load secrets locally.

3. Next, update the tests as necessary. A test file has already been generated by the go run hack/generate/generate.go command from earlier. There are 5 cases that have been generated:

   1. Found and verified (using a credential loaded from the .env file)
   2. Found and unverified (determinately, i.e. the secret is invalid)
   3. Found and unverified (indeterminately due to timeout)
   4. Found and unverified (indeterminately due to an unexpected API response)
   5. Not found

   Make any necessary updates to the tests. Note there might not be any changes required as the tests generated by the go run hack/generate/generate.go command are pretty good. Here is an exemplary test file for a detector which covers all 5 test cases.

4. Now run the tests and check to make sure they are passing ✔️!

   go test ./pkg/detectors/<detector> -tags=detectors

If the tests are passing, feel free to open a PR!

Addendum

Verification indeterminacy

There are two types of reasons that secret verification can fail:

• The candidate secret is not actually a valid secret.
• Something went wrong in the process unrelated to the candidate secret, such as a transient network error or an unexpected API response.

In TruffleHog parlance, the first type of verification response is called determinate and the second type is called indeterminate. Verification code should distinguish between the two by returning an error object in the result struct only for indeterminate failures. In general, a verifier should return an error (indicating an indeterminate failure) in all cases that haven't been explicitly identified as determinate failure states.

For example, consider a hypothetical authentication endpoint that returns 200 OK for valid credentials and 403 Forbidden for invalid credentials. The verifier for this endpoint could make an HTTP request and use the response status code to decide what to return:

• A 200 response would indicate that verification succeeded. (Or maybe any 2xx response.)
• A 403 response would indicate that verification failed determinately and no error object should be returned.
• Any other response would indicate that verification failed indeterminately and an error object should be returned.

Adding Protos in Windows

1. Install Ubuntu App in Microsoft Store https://www.microsoft.com/en-us/p/ubuntu/9nblggh4msv6.
2. Install Docker Desktop https://www.docker.com/products/docker-desktop. Enable WSL integration to Ubuntu. In Docker app, go to Settings->Resources->WSL INTEGRATION->enable Ubuntu.
3. Open Ubuntu cli and install dos2unix.
   bashCopy

   sudo apt install dos2unix
   

4. Identify the trufflehog local directory and convert scripts/gen_proto.sh file in Unix format.
   bashCopy

   dos2unix ./scripts/gen_proto.sh
   

5. Open /proto/detector_type.proto file and add new detectors then save it. Make sure Docker is running and run this in Ubuntu command line.
   bashCopy

   make protos