javascript.browser.security.wildcard-postmessage-configuration.wildcard-postmessage-configuration

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LGPL Commons Clause
License

The target origin of the window.postMessage() API is set to "*". This could allow for information disclosure due to the possibility of any origin allowed to receive the message.

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Defintion

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rules:
  - id: wildcard-postmessage-configuration
    message: The target origin of the window.postMessage() API is set to "*". This
      could allow for information disclosure due to the possibility of any
      origin allowed to receive the message.
    metadata:
      owasp:
        - A08:2021 - Software and Data Integrity Failures
      cwe:
        - "CWE-345: Insufficient Verification of Data Authenticity"
      category: security
      technology:
        - browser
      subcategory:
        - audit
      likelihood: HIGH
      impact: MEDIUM
      confidence: MEDIUM
      references:
        - https://owasp.org/Top10/A08_2021-Software_and_Data_Integrity_Failures
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    languages:
      - javascript
      - typescript
    severity: WARNING
    pattern: $OBJECT.postMessage(...,'*')

Examples

wildcard-postmessage-configuration.js

let data={pName : "Bob", pAge: "35"};
var popup = window.open(/* popup details */);

//ruleid:wildcard-postmessage-configuration
popup.postMessage(data, '*');
//ruleid:wildcard-postmessage-configuration
popup.postMessage( JSON.stringify( data ), '*' );

//postMessage Safe Usage
popup.postMessage("hello there!", "http://domain.tld");
popup.postMessage( JSON.stringify( data ), 'semgrep.dev/editor');