How to Scan ZIP files for Viruses, Malware, and Other Threats in Node.js

The distribution of malicious ZIP files is a common (and often quite effective attack) vector. ZIP files can easily hide compressed virus- or malware-infected files, and threat actors can also pack them with a high volume of gigantic files to crash systems and trigger Denial of Service attacks.

Thankfully, using a free API, we can easily dig into ZIP files and check the internal contents for virus and malware threats, as well as images, HTML, executables, and other potential threats. In our API response, we’ll also return a special value called “ContainsUnsafeArchive” which identifies overly large ZIP files (and other archive formats). We can use this secondary response to block ZIP files that may be intended to crash our system.

We can structure our API call in a few quick steps. First, we’ll want to get a free Cloudmersive API key; this will allow us to make up to 800 API calls per month with no commitments.

To install the SDK via NPM install, let’s run the following command:

npm install cloudmersive-virus-api-client --save

Alternatively, we can simply copy this snippet into our package.json:

  "dependencies": {
    "cloudmersive-virus-api-client": "^1.1.9"
  }

Finally, we can call the function using the remaining code examples. We can set custom threat rules in the API request body to our liking:

var CloudmersiveVirusApiClient = require('cloudmersive-virus-api-client');
var defaultClient = CloudmersiveVirusApiClient.ApiClient.instance;

// Configure API key authorization: Apikey
var Apikey = defaultClient.authentications['Apikey'];
Apikey.apiKey = 'YOUR API KEY';



var apiInstance = new CloudmersiveVirusApiClient.ScanApi();

var inputFile = Buffer.from(fs.readFileSync("C:\\temp\\inputfile").buffer); // File | Input file to perform the operation on.

var opts = { 
  'allowExecutables': true, // Boolean | Set to false to block executable files (program code) from being allowed in the input file.  Default is false (recommended).
  'allowInvalidFiles': true, // Boolean | Set to false to block invalid files, such as a PDF file that is not really a valid PDF file, or a Word Document that is not a valid Word Document.  Default is false (recommended).
  'allowScripts': true, // Boolean | Set to false to block script files, such as a PHP files, Python scripts, and other malicious content or security threats that can be embedded in the file.  Set to true to allow these file types.  Default is false (recommended).
  'allowPasswordProtectedFiles': true, // Boolean | Set to false to block password protected and encrypted files, such as encrypted zip and rar files, and other files that seek to circumvent scanning through passwords.  Set to true to allow these file types.  Default is false (recommended).
  'allowMacros': true, // Boolean | Set to false to block macros and other threats embedded in document files, such as Word, Excel and PowerPoint embedded Macros, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
  'allowXmlExternalEntities': true, // Boolean | Set to false to block XML External Entities and other threats embedded in XML files, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
  'allowInsecureDeserialization': true, // Boolean | Set to false to block Insecure Deserialization and other threats embedded in JSON and other object serialization files, and other files that contain embedded content threats.  Set to true to allow these file types.  Default is false (recommended).
  'allowHtml': true, // Boolean | Set to false to block HTML input in the top level file; HTML can contain XSS, scripts, local file accesses and other threats.  Set to true to allow these file types.  Default is false (recommended) [for API keys created prior to the release of this feature default is true for backward compatability].
  'restrictFileTypes': "restrictFileTypes_example" // String | Specify a restricted set of file formats to allow as clean as a comma-separated list of file formats, such as .pdf,.docx,.png would allow only PDF, PNG and Word document files.  All files must pass content verification against this list of file formats, if they do not, then the result will be returned as CleanResult=false.  Set restrictFileTypes parameter to null or empty string to disable; default is disabled.
};

var callback = function(error, data, response) {
  if (error) {
    console.error(error);
  } else {
    console.log('API called successfully. Returned data: ' + data);
  }
};
apiInstance.scanFileAdvanced(inputFile, opts, callback);

Now we can easily protect our Node.js forms from insecure ZIP uploads with just a few lines of code.