gitleaks: A Go repository from iCarossio

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░    gitleaks

Gitleaks is a SAST tool for detecting and preventing hardcoded secrets like passwords, api keys, and tokens in git repos. Gitleaks is an easy-to-use, all-in-one solution for detecting secrets, past or present, in your code.

Getting Started

Gitleaks can be installed using Homebrew, Docker, or Go. Gitleaks is also available in binary form for many popular platforms and OS types on the releases page. In addition, Gitleaks can be implemented as a pre-commit hook directly in your repo.

MacOS

brew install gitleaks

Docker

DockerHub

docker pull zricethezav/gitleaks:latest
docker run -v ${path_to_host_folder_to_scan}:/path zricethezav/gitleaks:latest [COMMAND] --source="/path" [OPTIONS]

ghrc.io

docker pull ghcr.io/zricethezav/gitleaks:latest
docker run -v ${path_to_host_folder_to_scan}:/path zricethezav/gitleaks:latest [COMMAND] --source="/path" [OPTIONS]

From Source

Download and install Go from https://golang.org/dl/
Clone the repo

git clone https://github.com/zricethezav/gitleaks.git

Build the binary

cd gitleaks
make build

Pre-Commit

Install pre-commit from https://pre-commit.com/#install
Create a .pre-commit-config.yaml file at the root of your repository with the following content:

repos:
  - repo: https://github.com/zricethezav/gitleaks
    rev: v8.2.0
    hooks:
      - id: gitleaks

Install with pre-commit install
Now you're all set!

➜ git commit -m "this commit contains a secret"
Detect hardcoded secrets.................................................Failed

Note: to disable the gitleaks pre-commit hook you can prepend SKIP=gitleaks to the commit command and it will skip running gitleaks

➜ SKIP=gitleaks git commit -m "skip gitleaks check"
Detect hardcoded secrets................................................Skipped

Usage

Usage:
  gitleaks [command]

Available Commands:
  completion  generate the autocompletion script for the specified shell
  detect      Detect secrets in code
  help        Help about any command
  protect     Protect secrets in code
  version     Display gitleaks version

Flags:
  -c, --config string          config file path
                               order of precedence:
                               1. --config/-c
                               2. env var GITLEAKS_CONFIG
                               3. (--source/-s)/.gitleaks.toml
                               If none of the three options are used, then gitleaks will use the default config
      --exit-code string       exit code when leaks have been encountered (default: 1)
  -h, --help                   help for gitleaks
  -l, --log-level string       log level (debug, info, warn, error, fatal) (default "info")
      --redact                 redact secrets from logs and stdout
  -f, --report-format string   output format (json, csv, sarif)
  -r, --report-path string     report file
  -s, --source string          path to source (git repo, directory, file)
  -v, --verbose                show verbose output from scan

Use "gitleaks [command] --help" for more information about a command.

Commands

There are two commands you will use to detect secrets; detect and protect.

Detect

The detect command is used to scan repos, directories, and files. This comand can be used on developer machines and in CI environments.

When running detect on a git repository, gitleaks will parse the output of a git log -p command (you can see how this executed here). git log -p generates patches which gitleaks will use to detect secrets. You can configure what commits git log will range over by using the --log-opts flag. --log-opts accepts any option for git log -p. For example, if you wanted to run gitleaks on a range of commits you could use the following command: gitleaks --source . --log-opts="--all commitA..commitB". See the git log documentation for more information.

You can scan files and directories by using the --no-git option.

Protect

The protect command is used to uncommitted changes in a git repo. This command should be used on developer machines in accordance with shifting left on security. When running protect on a git repository, gitleaks will parse the output of a git diff command (you can see how this executed here). You can set the --staged flag to check for changes in commits that have been git added. The --staged flag should be used when running Gitleaks as a pre-commit.

NOTE: the protect command can only be used on git repos, running protect on files or directories will result in an error message.

Verify Findings

You can verify a finding found by gitleaks using a git log command. Example output:

{
        "Description": "AWS",
        "StartLine": 37,
        "EndLine": 37,
        "StartColumn": 19,
        "EndColumn": 38,
        "Match": "\t\t\"aws_secret= \\\"AKIAIMNOJVGFDXXXE4OA\\\"\":          true,",
        "Secret": "AKIAIMNOJVGFDXXXE4OA",
        "File": "checks_test.go",
        "Commit": "ec2fc9d6cb0954fb3b57201cf6133c48d8ca0d29",
        "Entropy": 0,
        "Author": "zricethezav",
        "Email": "thisispublicanyways@gmail.com",
        "Date": "2018-01-28 17:39:00 -0500 -0500",
        "Message": "[update] entropy check",
        "Tags": [],
        "RuleID": "aws-access-token"
}

We can use the following format to verify the leak:

git log -L {StartLine,EndLine}:{File} {Commit}

So in this example it would look like:

git log -L 37,37:checks_test.go ec2fc9d6cb0954fb3b57201cf6133c48d8ca0d29

Which gives us:

commit ec2fc9d6cb0954fb3b57201cf6133c48d8ca0d29
Author: zricethezav <thisispublicanyways@gmail.com>
Date:   Sun Jan 28 17:39:00 2018 -0500

    [update] entropy check

diff --git a/checks_test.go b/checks_test.go
--- a/checks_test.go
+++ b/checks_test.go
@@ -28,0 +37,1 @@
+               "aws_secret= \"AKIAIMNOJVGFDXXXE4OA\"":          true,

Pre-Commit hook

You can run Gitleaks as a pre-commit hook by copying the example pre-commit.py script into your .git/hooks/ directory.

Configuration

Gitleaks offers a configuration format you can follow to write your own secret detection rules:

# Title for the gitleaks configuration file.
title = "Gitleaks title"

# An array of tables that contain information that define instructions
# on how to detect secrets
[[rules]]
# Unique identifier for this rule
id = "awesome-rule-1"
# Short human readable description of the rule.
description = "awsome rule 1"
# Golang regular expression used to detect secrets. Note Golang's regex engine
# does not support lookaheads.
regex = '''one-go-style-regex-for-this-rule'''
# Golang regular expression used to match paths. This can be used as a standalone rule or it can be used
# in conjunction with a valid `regex` entry.
path = '''a-file-path-regex'''
# Array of strings used for metadata and reporting purposes.
tags = ["tag","another tag"]
# Int used to extract secret from regex match and used as the group that will have
# its entropy checked if `entropy` is set.
secretGroup = 3
# Float representing the minimum shannon entropy a regex group must have to be considered a secret.
entropy = 3.5
# You can include an allowlist table for a single rule to reduce false positives or ignore commits
# with known/rotated secrets
[rules.allowlist]
description = "ignore commit A"
commits = [ "commit-A", "commit-B"]
paths = ['''one-file-path-regex''']
regexes = ['''one-regex-within-the-already-matched-regex''']

# This is a global allowlist which has a higher order of precendence than rule-specific allowlists.
# If a commit listed in the `commits` field below is encountered then that commit will be skipped and no
# secrets will be detected for said commit. The same logic applies for regexes and paths.
[allowlist]
description = "ignore commit A"
commits = [ "commit-A", "commit-B"]
paths = ['''one-file-path-regex''']
regexes = ['''one-regex-within-the-already-matched-regex''']

Refer to the default gitleaks config for examples and advice on writing regular expressions for secret detection.

Tips on Writing Regular Expressions

Gitleaks rules are defined by regular expressions and entropy ranges. Some secrets have unique signatures which make detecting those secrets easy. Examples of those secrets would be Gitlab Personal Access Tokens, AWS keys, and Github Access Tokens. All these examples have defined prefixes like glpat, AKIA, ghp_, etc.

Other secrets might just be a hash which means we need to write more complex rules to verify that what we are matching is a secret.

Here is an example of a semi-generic secret

discord_client_secret = "8dyfuiRyq=vVc3RRr_edRk-fK__JItpZ"

We can write a regular expression to capture the variable name (identifier), the assignment symbol (like '=' or ':='), and finally the actual secret. The structure of a rule to match this example secret is below:

                                                       Beginning string
                                                           quotation
                                                               │            End string quotation
                                                               │                      │
                                                               ▼                      ▼
(?i)(discord[a-z0-9_ .\-,]{0,25})(=|>|:=|\|\|:|<=|=>|:).{0,5}['\"]([a-z0-9=_\-]{32})['\"]

               ▲                              ▲                                ▲
               │                              │                                │
               │                              │                                │
          identifier                  assignment symbol
                                                                            Secret

A Note on Generic Secrets

Let's continue with the example discord_client_secret = "8dyfuiRyq=vVc3RRr_edRk-fK__JItpZ". This secret would match both the discord-client-secret rule and the generic-api-key rule in the default config.

[[rules]]
id = "discord-client-secret"
description = "Discord client secret"
regex = '''(?i)(discord[a-z0-9_ .\-,]{0,25})(=|>|:=|\|\|:|<=|=>|:).{0,5}['\"]([a-z0-9=_\-]{32})['\"]'''
secretGroup = 3

[[rules]]
id = "generic-api-key"
description = "Generic API Key"
regex = '''(?i)((key|api|token|secret|password)[a-z0-9_ .\-,]{0,25})(=|>|:=|\|\|:|<=|=>|:).{0,5}['\"]([0-9a-zA-Z\-_=]{8,64})['\"]'''
entropy = 3.7
secretGroup = 4

If gitleaks encountered discord_client_secret = "8dyfuiRyq=vVc3RRr_edRk-fK__JItpZ", only the discord rule would report a finding because the generic rule has the string generic somewhere in the rule's id. If a secret is encountered and both a generic and non-generic rule have discovered the same secret, the non-generic will be given precedence.

Sponsorships

Exit Codes

You can always set the exit code when leaks are encountered with the --exit-code flag. Default exit codes below:

0 - no leaks present
1 - leaks or error encountered
126 - unknown flag

iCarossio/gitleaks