How to Check TAR Files for Threats in Node.js

TAR files are one of many archival formats capable of bypassing weakly configured security systems and triggering costly cyberattacks.

To mitigate attacks with TAR files, we need to dig deep into the compressed archive and look for a wide range of potential threats.

We don’t need to waste a ton of time coding to do that, however. Instead, we can call a free API capable of checking TAR files for viruses, malware, and other unsafe extraction outcomes (e.g., overly large files intended to crash a system; files with malicious macros, links, and other objects; etc.)

We can use code examples provided below to structure our API call. To authorize our requests, we’ll just need a free Cloudmersive API key, which will allow us a limit of 800 API calls per month with no additional commitments.

To install the SDK via NPM install, we run the following command:

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

We could also add the following snippet to our package.json instead:

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

To call the function, we can copy the below code examples into our file. We can set a few custom threat rules in our API request to specifically block generally threatening content types like executables, macros, scripts, html, and more:

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);

We’ll receive a “ContainsUnsafeArchive” item in our API response indicating (true/false) if our TAR file had an unsafe extraction outcome. This way, we can easily quarantine unsafe TAR files and avoid triggering a variety of common archive-based attacks.