COMMON WEAKNESS ENUMERATIONIncomplete

CWE-649

Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking

The product uses obfuscation or encryption of inputs that should not be mutable by an external actor, but the product does not use integrity checks to detect if those inputs have been modified.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

High

Understand the problem

What is the problem?

The product uses obfuscation or encryption of inputs that should not be mutable by an external actor, but the product does not use integrity checks to detect if those inputs have been modified.

Extended description

When an application relies on obfuscation or incorrectly applied / weak encryption to protect client-controllable tokens or parameters, that may have an effect on the user state, system state, or some decision made on the server. Without protecting the tokens/parameters for integrity, the application is vulnerable to an attack where an adversary traverses the space of possible values of the said token/parameter in order to attempt to gain an advantage. The goal of the attacker is to find another admissible value that will somehow elevate their privileges in the system, disclose information or change the behavior of the system in some way beneficial to the attacker. If the application does not protect these critical tokens/parameters for integrity, it will not be able to determine that these values have been tampered with. Measures that are used to protect data for confidentiality should not be relied upon to provide the integrity service.

Root cause

How and when does the problem arise?

Lifecycle phase

Architecture and Design

OMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.

Lifecycle phase

Implementation

Risk

What does successful exploitation lead to?

Unexpected State

Affected security scopes: Integrity

The inputs could be modified without detection, causing the product to have unexpected system state or make incorrect security decisions.

Defence

How is it prevented and fixed?

Architecture and Design

Architecture and design approach

Detail
Protect important client controllable tokens/parameters for integrity using PKI methods (i.e. digital signatures) or other means, and checks for integrity on the server side.

Architecture and Design

Architecture and design approach

Detail
Repeated requests from a particular user that include invalid values of tokens/parameters (those that should not be changed manually by users) should result in the user account lockout.

Architecture and Design

Architecture and design approach

Detail
Client side tokens/parameters should not be such that it would be easy/predictable to guess another valid state.

Architecture and Design

Architecture and design approach

Detail
Obfuscation should not be relied upon. If encryption is used, it needs to be properly applied (i.e. proven algorithm and implementation, use padding, use random initialization vector, user proper encryption mode). Even with proper encryption where the ciphertext does not leak information about the plaintext or reveal its structure, compromising integrity is possible (although less likely) without the provision of the integrity service.