What are serialisation and deserialisation attacks and how to prevent them?

Serialisation and deserialisation are important concepts in computer programming that involve converting data into a format that can be stored, transmitted, or processed. Serialisation refers to the process of converting objects or data structures into a binary or text format, while deserialisation is the process of reconstructing the original objects or data structures from the serialised data.

While serialisation and deserialisation are important techniques for data processing and communication, they can also introduce security risks if not implemented properly. In this blog, we will explore the security implications of serialisation and deserialisation and how to mitigate these risks.

Serialisation and Deserialisation Attacks

One of the most common security risks associated with serialisation and deserialisation is the possibility of a malicious actor exploiting these processes to execute arbitrary code or perform other unauthorised actions on the application or system. This can happen in a number of ways, including:

1. Injection Attacks: Attackers can exploit vulnerabilities in the serialisation or deserialisation process to inject malicious code into the application or system. This can allow them to execute arbitrary code, steal data, or perform other malicious actions.

2. Tampering Attacks: Attackers can modify the serialised data in transit to alter the behavior of the application or system. For example, an attacker could modify a serialised object to give themselves administrative privileges.

3. Denial of Service Attacks: Attackers can use serialisation and deserialisation to launch denial of service attacks by flooding the application or system with large amounts of data. This can overwhelm the system and cause it to crash or become unresponsive.

Preventing Serialisation and Deserialisation Attacks

To prevent serialisation and deserialisation attacks, there are several steps that application developers can take:

1. Validate Input: Validate all input data to ensure that it is properly formatted and does not contain any malicious code. This can help prevent injection attacks and tampering attacks.

2. Use Secure Serialisation Formats: Use secure serialisation formats that are less prone to vulnerabilities. For example, JSON and XML are less secure than binary serialisation formats like Protobuf or Thrift.

3. Implement Secure Deserialisation: Implement secure deserialisation by using libraries or frameworks that have built-in security features. For example, the Java Deserialisation Scanner can help detect potential vulnerabilities in Java applications.

4. Limit Data Size: Limit the size of data that can be deserialised to prevent denial of service attacks. This can be done by setting limits on the amount of data that can be deserialised or by using streaming deserialisation techniques.

5. Keep Libraries and Frameworks Up to Date: Keep all libraries and frameworks used in the application up to date to ensure that any security vulnerabilities are patched.

Conclusion

Serialisation and deserialisation are important techniques for data processing and communication in modern applications. However, they also introduce security risks that must be carefully managed. By implementing best practices for serialisation and deserialisation, such as validating input, using secure serialisation formats, and implementing secure deserialisation, application developers can help mitigate these risks and ensure the security of their applications.