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Semgrep Secrets overview

Semgrep Secrets scans code to detect exposed API keys, passwords, and other credentials. When exposed, these can be used by malicious actors to leak data or gain access to sensitive systems. Semgrep Secrets allows you to determine:

  • What secrets have been committed to your repository.
  • The validation status of the secret; for example, valid secrets are those that have been tested against a web service and confirmed to successfully grant resources or authentication. They are actively in use.
  • For GitHub repositories: if there are credentials in public or private repositories.

Semgrep saves security engineers time and effort by prioritizing valid leaked secrets and informs developers of valid secrets in their PRs and MRs by posting comments directly.

How Semgrep Secrets works​

To ensure that findings are high-signal, comprehensive, and easy for users to prioritize, a Semgrep Secrets scan performs the following:

  • Search using regex
  • Semantic analysis
  • Validation
  • Entropy analysis

The following sections explain how each step works.

Detect secrets through regex​

Semgrep Secrets uses a regex language detector to find secrets in various file types. This is done by detecting a commonly defined prefix and then searching for the secret using its expected length and format.

To reduce the number of false positives this process raises, Semgrep uses and combines as many of the following processes with its search using regex when possible:

  • Removal of results that are likely to be false positives
  • Validation
  • Entropy analysis

Detect secrets through semantic analysis​

Semantic analysis refers to Semgrep Secrets' ability to understand how data is used within your code. This differentiates Semgrep Secrets from regex-based detectors that simply define a pattern to match a piece of code.

Semgrep Secrets uses several mechanisms to perform semantic analysis. It uses data-flow analysis and constant propagation which means that it is able to track data, such as variables, and the flow of that data across files and functions in your codebase.

Performing semantic analysis is encapsulated in rules. By running these rules, Semgrep Secrets is able to detect if a variable is renamed, reassigned, or used in a function in such a way that a secret is exposed.

See the following rule and JavaScript test code for an example.


Validate secrets​

After scanning your codebase, Semgrep Secrets uses a proprietary validator to determine if a secret is actively being used or some other state if there is a validator defined in the rule used.

info

All validations, such as API calls, are done locally in your environment. No tokens are sent to Semgrep servers.

  1. The validator detects the service, such as Slack or AWS, that the secret is used for.
  2. If the validator doesn't support the service that the secret is used for, Semgrep notes that there is No validator finding for the secret.
  3. Semgrep Secrets performs an API call if the validator supports the service. The following outcomes can occur:
    1. Confirmed valid: Semgrep made an HTTP request using the secret, and it returned an HTTP status code of 200 or similar and some indication of valid access. For example, a service can include a "message": "ok" in the response body.
    2. Confirmed invalid: Semgrep made an HTTP request using the secret and it returned an HTTP status code of 401 or similar.
    3. Validation error: Semgrep made an HTTP request using the secret, but either the network request could not be made, a timeout occurred, or the HTTP status code returned a different HTTP status code. In this case, the Semgrep Team recommends manually reviewing the finding.
    4. No Validator: The rule does not have a validator.

By performing this validation check, you can prioritize and triage the most high-priority, active findings.

note
  • For a list of all supported detectors that Semgrep offers, see the Policies page in your deployment.
  • See Validators for syntax and examples.

Fine-tune findings through entropy analysis​

Entropy is the measure of a string's randomness. It's used to measure how likely a string is random. If a string is highly entropic, it's highly random. For certain types of secrets, such as API keys, randomness indicates that a string could be a secret. By performing entropy analysis, Semgrep Secrets can reduce false positives and produce more true positives.

Examples of high-entropy (random) strings:

VERZVs+/nd56Z+/Qxy1mzEqqBwUS1l9D4YbqmPoOß
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

Examples of low-entropy strings:

XXXXXX
txtPassword1

Next steps​

See Scan for secrets to learn how to:

  • Enable secrets scanning for your repositories
  • Manage your rules in your policy to have complete control over how
  • View and triage secrets-related findings
  • Receive notifications and post tickets whenever Semgrep Secrets identifies issues
  • Write custom rules with validators to find bespoke secrets

Not finding what you need in this doc? Ask questions in our Community Slack group, or see Support for other ways to get help.