How to Detect and Block Insecure Deserialization Attempts in File Uploads using Python

Insecure deserialization is most often associated with JSON files, but the reality is a variety of different frameworks can be used to exploit weakly configured data parsers in the deserialization process.

No matter what form it takes, blocking insecure deserialization threats starts with carefully evaluating and improving your data parser’s security policies. That can mean implementing specific detection services, or incorporating comprehensive, multi-faceted security solutions. The free-to-use API provided below simultaneously detects insecure deserialization attempts AND scans files for millions of virus and malware signatures, offering a significant value-add service for any file upload/data download workflow.

You can take advantage of this API in two easy steps. Start by running the below command to install the Python SDK with pip install:

pip install cloudmersive-virus-api-client

Then copy and paste the ready-to-run code examples below to structure your API call:

from __future__ import print_function
import time
import cloudmersive_virus_api_client
from cloudmersive_virus_api_client.rest import ApiException
from pprint import pprint

# Configure API key authorization: Apikey
configuration = cloudmersive_virus_api_client.Configuration()
configuration.api_key['Apikey'] = 'YOUR_API_KEY'



# create an instance of the API class
api_instance = cloudmersive_virus_api_client.ScanApi(cloudmersive_virus_api_client.ApiClient(configuration))
input_file = '/path/to/inputfile' # file | 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). (optional)
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). (optional)
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). (optional)
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). (optional)
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). (optional)
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). (optional)
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). (optional)
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]. (optional)
restrict_file_types = 'restrict_file_types_example' # str | 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. (optional)

try:
    # Advanced Scan a file for viruses
    api_response = api_instance.scan_file_advanced(input_file, allow_executables=allow_executables, allow_invalid_files=allow_invalid_files, allow_scripts=allow_scripts, allow_password_protected_files=allow_password_protected_files, allow_macros=allow_macros, allow_xml_external_entities=allow_xml_external_entities, allow_insecure_deserialization=allow_insecure_deserialization, allow_html=allow_html, restrict_file_types=restrict_file_types)
    pprint(api_response)
except ApiException as e:
    print("Exception when calling ScanApi->scan_file_advanced: %s\n" % e)

You can now set a custom policy against files containing insecure deserialization (and a vareity of other non-malware content threats) by setting the allowInsecureDeserialization boolean to “False” in the request body. To authorize your request, supply a free-tier Cloudmersive API key (this allows a limit of 800 API calls per month with no commitments).