How to Restrict File Uploads using Ruby Code Examples

File upload restriction is common security practice these days, especially given the limited number of file types that are actually necessary to fulfill a user upload process. There are, for example, dozens of image file formats available to us, but we can instantly improve our social website’s file storage threat profile if we limit those uploads to common formats like JPG, PNG and GIF.

The below API request code examples (provided in Ruby) will allow you to scan files for millions of virus and malware threats, identify a variety of hidden content threats, and perform in-depth verification against a custom list of comma-separated file extensions. Files with contents that do NOT match the extensions on that list will be categorized as infected, returning a “CleanResult: False” value in the API response body.

You can easily structure your API call by first installing the SDK (add the below Ruby client to your Gemfile):

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

And subsequently coping the aforementioned code examples into your file:

# 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

You can authorize your request for free (with a limit of 800 API calls per month) by registering a free account on the Cloudmersive website & copying your free-tier API key into the appropriate configuration field.