How to Detect and Remove Scripts from a File Upload Process in Node.js

Common, everyday files like PDF can play host to malicious code embedded by client-side threat actors. Scripts — written in PHP, Python, or a variety of other programming languages — can be executed within our system if they’re left undetected, resulting in disastrous data loss or compromising control of our system entirely.

Setting the allowScripts Boolean to “false” in the Advanced Virus Scan API request body below allows you to block scripts detected within file uploads before they can reach a more sensitive layer of your system. As the name suggests, this API also checks file uploads for virus and malware threats, ultimately offering 360-degree content protection with full file verification policies.

To get up and running with Node.js code examples, start by installing the Node.js SDK with npm install:

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

Or — if you prefer — add this snippet to your package.json instead:

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

With installation out of the way, copy the below code examples to structure your API call. Provide a free-tier Cloudmersive API key to authenticate (this allows a limit of 800 API calls per month with no additional commitments) and set the allowScripts Boolean to “false”:

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 any files carrying viruses, malware OR scripts within their encoding will receive a CleanResult: False value in the API response body. This makes it easy to delete (or quarantine) dangerous files and thereby avert a significant security risk.