Investigating Package Hunter Findings

List of Package Hunter Findings

Any Package Hunter related finding can be found on this dashboard (internal link).

Network Connection Findings

We’re going to use this finding as an example. In this finding, Package Hunter detected that a package opened a network connection.

02:24:56.163600570: Notice Disallowed outbound connection destination (command=node scripts/install.js connection=172.17.0.2:36884->52.217.109.44:443 user=root container_id=fb38d63ef02a container_name=some-container-eae8d3ec-a482-441b-8262-78198b46fdfb.tgz image=maldep)

Investigation

• We can look at the destination IP address and see if gives any interesting information
  • In this example, it’s a an AWS IP address but it gives us no information about what package might have contacted this IP
• Attention: This step requries to checkout the branch for which the finding was made. Please proceed with caution when analyzing potentially malicious code on your local computer. We recommend to checkout the code into a dedicated VM. If there are any questions or you require assistance, please reach out to @gitlab-com/gl-security/product-security/appsec.
  • We know that the package ran the command scripts/install.js so we can search for that file (be sure to execute yarn install before running the search)
  • Running find . -name install.js leads us to node_modules/node-sass/scripts/install.js
• We can inspect the package.json files to find the command that triggered the detection
  • We see in node_modules/node-sass/package.json that scripts/install.js is indeed called

Completing the investigation in the example, we see that the install.js script calls getBinaryURL(). This function is defined in node_modules/node-sass/lib/extensions.js:

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/**
 * Determine the URL to fetch binary file from.
 * By default fetch from the node-sass distribution
 * site on GitHub.
 */
function getBinaryUrl() {
  var site = getArgument('--sass-binary-site') ||
             process.env.SASS_BINARY_SITE  ||
             process.env.npm_config_sass_binary_site ||
             (pkg.nodeSassConfig && pkg.nodeSassConfig.binarySite) ||
             'https://github.com/sass/node-sass/releases/download';  return [site, 'v' + pkg.version, getBinaryName()].join('/');
}

We see from this file that node-sass is trying to download the binary from https://github.com/sass/node-sass/releases/download/VERSION/BINARY_NAME

Doing this locally we obtain:

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$ wget https://github.com/sass/node-sass/releases/download/v5.0.0/linux-x64-64_binding.node
...
Connecting to github-production-release-asset-2e65be.s3.amazonaws.com (github-production-release-asset-2e65be.s3.amazonaws.com)|52.216.204.107|:443... connected.
...

It’s resolving the URL to 52.216.204.107, which is not exactly the same IP from the Package Hunter finding, but IP address info is very similar and it’s normal that the request wouldn’t exactly be served by the same IP every time in this context. At this point we can be reasonably sure about the source of the alert and that there is no malicious intent.

Actions

• If we discover that the package was malicious all along (typosquatting for example), security on-call should be engaged for further investigation and an MR should be opened to replace the package with the legitimate one. Consider reporting the malicious package to the registry operator (NPM) or RubyGems)
• If we discover that a legitimate package was compromised, security on-call should be engaged for further investigation and an MR should be opened to roll back to a previous version of the package that is known to be secure. Consider reporting the malicious package to the registry operator (NPM or RubyGems) and to the maintainer of the package
• If we discover that the network connection is used to fetch a legitimate resource, we should look into the possibility of self-hosting the resource or verifying its integrity during the build process to protect against a potential compromise of the external resource

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