gitdetect

gitdetect

A Github scanning tool to help you find misplaced secrets in your source code repository files. gitdetect uses compound rules that combine regular expressions with an entropy threshold allowing a greatly reduced rate of false positive detections relative to other tools. gitdetect can also scan an arbitrary directory on the local filesystem.

Sample Configuration File

The following yaml configuration file may be used to find AWS secret keys

secret-detection-rules:
- target:
  - \"(?P<suspect>[A-Za-z0-9\/+]{40})\"
  - '''(?P<suspect>[A-Za-z0-9\/+]{40})'''
  except:
  - \"EXAMPLE([A-Za-z0-9\/+]{33})\"
  - '''EXAMPLE([A-Za-z0-9\/+]{33})'''
  entropy: 4.5
  tag: AWS_SEC
  exploitfn: AwsSTS

- target:
  - \"(?P<suspect>sec[A-Za-z0-9\/+]{37})\"
  - '''(?P<suspect>sec[A-Za-z0-9\/+]{37})'''
  entropy: 4.5
  tag: MY_OTHER_SEC_TYPE

Description

target: List of regular expressions where a match with any one of the expressions is required to continue evaluation.
except: Exclusion list of regular expressions where a match with any one of the expressions disqualifies a target match. If no match is made, evaluation of the compound rule continues.
entropy: Minimum threshold value as measured by the Shanon Entropy of the matched string.
tag: Descriptive text to afix to a reported match.
exploitfn: The name of the method to call when a secret is detected. This method must be defined in the secret/exploit package with the *Exploit. Any data set in Exploit.Output will be shown as . Gitdetect contains one such method called AwsSTS which is used to determine if a suspected AWS secret key is active.

For example, "wJalrXUtnFEMI/K7MDENG/bPxRfiCYKEYEXAMPLE" will be detected by the above rule because it matches the first regular expression listed under target, it does not match any of the regular expressions listed under except and it has a shanon entropy value greater or equal to 4.5.

Note each target expressions has a named capturing group suspect (?P<suspect>), an optional keyword recoginized by gitdetect. When used, gitdetect applies the entropy threshold to the named group only. In the above example if the suspect group name was not used the entropy threshold would be applied to the entire matched string which includes the surrounding quotes.

Usage of gitdetect:

  -access-token string
    	github access token.
  -github-hostname string
    	github url hostname (default "github.com")
  -last-modified-cutoff int
    	The repository will not be scanned unless it was modified in the last number of days specified here. 0 indicates scan always.
  -local-scan-dir string
    	The local directory path to scan.  When set, github related options are ignored.
  -output-dir string
    	working dir and report genaration dir.
  -repo-name string
    	Fully qualified repo name in the format <owner>/<name>/[<branch>] e.g. my-org/my-proj for the default branch or my-org/my-proj/my-feature-branch. Leave blank for a full github scan.
  -rule-config string
    	Full path name of the detection rule configuration file.

Example Usage

Scan the gitdetect repository under the ABC org:

./gitdetect -access-token 73f5921499a9191817640d5e94486b50c0916c67 -rule-config gitdetect.conf.yaml -output ./myoutput -repo-name ABC/gitdetect

Scan all public repositories on the XYZ enterprise Github:

./gitdetect -github-hostname xyz.github.com -access-token 73f5921499a9191817640d5e94486b50c0916c67 -rule-config gitdetect.conf.yaml -output ./myoutput

Scan the local directory /home/jsmith/myapp

./gitdetect -rule-config gitdetect.conf.yaml -output /home/jsmith -local-scan-dir /home/jsmith/myapp

Defect Report

When gitdetect finishes running it will create a report file in the output directory named defectReport.yaml. Following is a sample report created by gitdetect

repositories:
  ? id: 101287
    org: myorg
    name: gitdetect
    branch: master
    head: 1234556412345123451234512345123458912345
    last-push: "2019-10-17"
  : defects:
      ? filename: test/filerepo/TwoDistinctSecrets.txt
      : - lines:
          - 4
          tag: AWS_SEC
        - lines:
          - 5
          tag: AWS_SEC
      ? filename: test/filerepo/TwoIdenticalSecrets.txt
      : - lines:
          - 4
          - 5
          tag: AWS_SEC
      ? filename: test/filerepo/activeSecret.go
      : - lines:
          - 4
          tag: AWS_SEC
          additional-info: '{"Account":"testaccount","Arn":"testarn","UserId":"testuserid"}'
      ? filename: README.md
      : - lines:
          - 45
          tag: AWS_SEC
      ? filename: test/filerepo/OneSecret.txt
      : - lines:
          - 3
          tag: AWS_SEC
defectcount: 7

Noteworthy fields:

additional-info: When a secret is confirmed to be active as determined by the optional exploitfn, func (exploit *Exploit) AwsSTS() bool may set Exploit.Output with any relevant JSON formatted data. The data will be shown in this field.

Regular Expressions Syntax

gitdetect supports the golang RE2 subset of the PCRE syntax. This means that backtracing is not supported. For this reason the above example uses two separate expression, a single quote and a double quote version where a single expression would have been possible with PCRE backtracing. The upside is improved performance.

Contributions

gitdetect welcomes contributions from everyone. Please refer to the documentation under .github/CONTRIBUTING before submitting your pull request.