How to Check PowerPoint PPSX Files for Threats in Node.js

PowerPoint’s slideshow format — PPSX — has been used effectively in several malware attacks in the last decade. Like any other Office file format, PPSX can be manipulated in a variety of ways to breach our applications and systems.

As far back as 2017, for example, zero-day vulnerabilities were identified in PPSX object linking & embedding (OLE) capabilities that could lead to remote code execution attacks.

Attacks using common, innocuous formats like PPSX are only becoming more frequent and creative over time, and it’s important that we implement dynamic threat detection policies in response.

Thankfully, using the Node.js code examples provided below, we can call a free API that checks PPSX files (and all other major Office file formats, PDFs, and 100+ unique image formats) for OLE threats, Macro threats, viruses, malware, and a wide range of additional threatening content types.

To take advantage of this API, we can start by installing the client SDK. We can run the below command to install via NPM install:

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

Or we can add this snippet to our package.json:

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

To call the function, we can implement the below code examples into our file. We can use request variables to set custom threat rules against macros, scripts, invalid PPSX files, 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);

The last thing we’ll need is a free Cloudmersive API key. This will allow us to make up to 800 API calls per month with zero commitments (our total will reset the following month once we reach it).

We can now easily scan our PPSX files for a wide range of common threats with just a few lines of Node.js code.