How to Scan File Uploads for Threats in PHP

Virus and malware-infected files aren’t the only threats we’ll find uploaded to our servers. Disguised scripts and executables, Office documents with enabled macros, and PDFs containing JavaScript or HTML code are just a few examples of threats most antivirus software won’t detect.

Thankfully, using complementary, ready-to-run PHP code examples provided below, we can easily take advantage of a free API that scans files for viruses, malware, and a variety of non-malware content threats. The underlying threat-scanning sandbox will detect a wide range of potential threats (indicated in the example JSON response model below):

{
  "CleanResult": true,
  "ContainsExecutable": true,
  "ContainsInvalidFile": true,
  "ContainsScript": true,
  "ContainsPasswordProtectedFile": true,
  "ContainsRestrictedFileFormat": true,
  "ContainsMacros": true,
  "ContainsXmlExternalEntities": true,
  "ContainsInsecureDeserialization": true,
  "ContainsHtml": true,
  "ContainsUnsafeArchive": true,
  "ContainsOleEmbeddedObject": true,
  "VerifiedFileFormat": "string",
  "FoundViruses": [
    {
      "FileName": "string",
      "VirusName": "string"
    }
  ],
  "ContentInformation": {
    "ContainsJSON": true,
    "ContainsXML": true,
    "ContainsImage": true,
    "RelevantSubfileName": "string"
  }
}

We can configure corresponding threat rules in our API configuration to directly flag some of the above content types as threats.

If, for example, we wanted executable content to trigger a “CleanResult: false” response, we could set the $allow_executables variable to “false”. This means files containing executable content would be treated the same as files carrying viruses and malware.

To begin structuring our API call, let’s first install the PHP client using Composer. We can execute the following command from the command line:

composer require cloudmersive/cloudmersive_virusscan_api_client

Next, let’s turn our attention to authorization. We’ll need a free API key to authorize our requests — this will allow a limit of 800 API calls per month with no additional commitments (once we reach our limit, our total will reset the following month).

Finally, let’s use the below code examples to create an instance of the API and call the dynamic threat scanning function:

<?php
require_once(__DIR__ . '/vendor/autoload.php');

// Configure API key authorization: Apikey
$config = Swagger\Client\Configuration::getDefaultConfiguration()->setApiKey('Apikey', 'YOUR_API_KEY');



$apiInstance = new Swagger\Client\Api\ScanApi(
    
    
    new GuzzleHttp\Client(),
    $config
);
$input_file = "/path/to/inputfile"; // \SplFileObject | Input file to perform the operation on.
$allow_executables = true; // bool | Set to false to block executable files (program code) from being allowed in the input file.  Default is false (recommended).
$allow_invalid_files = true; // bool | 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).
$allow_scripts = true; // bool | 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).
$allow_password_protected_files = true; // bool | 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).
$allow_macros = true; // bool | 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).
$allow_xml_external_entities = true; // bool | 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).
$allow_insecure_deserialization = true; // bool | 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).
$allow_html = true; // bool | 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].
$restrict_file_types = "restrict_file_types_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.

try {
    $result = $apiInstance->scanFileAdvanced($input_file, $allow_executables, $allow_invalid_files, $allow_scripts, $allow_password_protected_files, $allow_macros, $allow_xml_external_entities, $allow_insecure_deserialization, $allow_html, $restrict_file_types);
    print_r($result);
} catch (Exception $e) {
    echo 'Exception when calling ScanApi->scanFileAdvanced: ', $e->getMessage(), PHP_EOL;
}
?>

Now we can perform advanced threat scans on file uploads using minimal code.