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CWE
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Deserialization of Untrusted Data

ID: 502Date: (C)2012-05-14   (M)2017-11-10
Type: weaknessStatus: DRAFT
Abstraction Type: Variant





Description

The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.

Extended Description

It is often convenient to serialize objects for communication or to save them for later use. However, deserialized data or code can often be modified without using the provided accessor functions if it does not use cryptography to protect itself. Furthermore, any cryptography would still be client-side security -- which is a dangerous security assumption.

Data that is untrusted can not be trusted to be well-formed.

Likelihood of Exploit: Medium

Applicable Platforms
Language Class: All

Time Of Introduction

  • Architecture and Design
  • Implementation

Common Consequences

ScopeTechnical ImpactNotes
Availability
 
DoS: resource consumption (CPU)
 
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
 
Authorization
Other
 
Other
 
Code could potentially make the assumption that information in the deserialized object is valid. Functions which make this dangerous assumption could be exploited.
 

Detection Methods
None

Potential Mitigations

PhaseStrategyDescriptionEffectivenessNotes
Requirements
 
 A deserialization library could be used which provides a cryptographic framework to seal serialized data.
 
  
Implementation
 
 Use the signing features of a language to assure that deserialized data has not been tainted.
 
  
Implementation
 
 When deserializing data populate a new object rather than just deserializing, the result is that the data flows through safe input validation and that the functions are safe.
 
  
Implementation
 
 Explicitly define final readObject() to prevent deserialization. An example of this is:

 
  
Architecture and Design
Implementation
 
 Make fields transient to protect them from deserialization.
An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
 
  

Relationships

Related CWETypeViewChain
CWE-502 ChildOf CWE-896 Category CWE-888  

Demonstrative Examples   (Details)

  1. This code snippet deserializes an object from a file and uses it as a UI button:

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings

TaxynomyIdNameFit
CLASP  Deserialization of untrusted data
 
 
CERT Java Secure Coding SER01-J
 
Do not deviate from the proper signatures of serialization methods
 
 
CERT Java Secure Coding SER03-J
 
Do not serialize unencrypted, sensitive data
 
 
CERT Java Secure Coding SER06-J
 
Make defensive copies of private mutable components during deserialization
 
 
CERT Java Secure Coding SER08-J
 
Do not use the default serialized form for implementation defined invariants
 
 

References:
None

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