Deserialization Cheat Sheet

Introduction

This article is focused on providing clear, simple, actionable guidance for safely deserializing untrusted data in your applications.

What is Deserialization?

Serialization is the process of turning some object into a data format that can be restored later. People often serialize objects in order to save them to storage, or to send as part of communications. Deserialization is the reverse of that process -- taking data structured from some format, and rebuilding it into an object. Today, the most popular data format for serializing data is JSON. Before that, it was XML.

Many programming languages offer a native capability for serializing their objects. These native formats usually offer more features than JSON or XML, including customizability of the serialization process. Unfortunately, the features of these native deserialization mechanisms can be repurposed for malicious effect when operating on untrusted data. Attacks against deserializers have been found to allow denial-of-service, access control, and remote code execution attacks.

The following cheatsheet attempts to dictate safe methodologies for deserializing data that can't be trusted.

References

• Deserialization of untrusted data

Authors and Primary Editors

Arshan Dabirsiaghi - arshan [at] contrastsecurity dot org

Other Cheatsheets

OWASP Cheat Sheets Project Homepage

• OWASP Cheat Sheet Series

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