How to Scan Files for Malware and Embedded Scripts using Ruby

In today’s frantically evolving cybersecurity landscape, it’s not enough to protect your applications against viruses and malware alone. Threat actors are continually finding new vulnerabilities to exploit in an attempt to launch devastating cyber-attacks, and many of those vulnerabilities are found in poorly configured file upload processes which fail to recognize disguised content threats.

Script files (such as PHP or Python) can indicate a serious threat, and it’s best to block them entirely. You can do so using the free API provided below; this solution will first check files for millions of virus and malware signatures, and subsequently perform full content verification to identify scripts, macros, executables, and a variety of other threat types. You can set the allow_scripts parameter to “false” to categorically block script files from bypassing your upload process.

To take advantage of this API for free, you’ll need a free-tier API key, which you can get on the Cloudmersive website with no additional commitment. To structure your API call, you can start by adding the Ruby client to your Gemfile:

gem 'cloudmersive-virus-scan-api-client', '~> 2.0.3'

Then you can copy the remaining code:

# load the gem
require 'cloudmersive-virus-scan-api-client'
# setup authorization
CloudmersiveVirusScanApiClient.configure do |config|
  # Configure API key authorization: Apikey
  config.api_key['Apikey'] = 'YOUR API KEY'
  # Uncomment the following line to set a prefix for the API key, e.g. 'Bearer' (defaults to nil)
  #config.api_key_prefix['Apikey'] = 'Bearer'
end

api_instance = CloudmersiveVirusScanApiClient::ScanApi.new

input_file = File.new('/path/to/inputfile') # File | Input file to perform the operation on.

opts = { 
  allow_executables: true, # BOOLEAN | Set to false to block executable files (program code) from being allowed in the input file.  Default is false (recommended).
  allow_invalid_files: 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).
  allow_scripts: 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).
  allow_password_protected_files: 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).
  allow_macros: 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).
  allow_xml_external_entities: 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).
  allow_insecure_deserialization: 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).
  allow_html: 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].
  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.
}

begin
  #Advanced Scan a file for viruses
  result = api_instance.scan_file_advanced(input_file, opts)
  p result
rescue CloudmersiveVirusScanApiClient::ApiError => e
  puts "Exception when calling ScanApi->scan_file_advanced: #{e}"
end

That’s all there is to it — no more code required.