COMMON WEAKNESS ENUMERATIONDraft

CWE-471

Modification of Assumed-Immutable Data (MAID)

The product does not properly protect an assumed-immutable element from being modified by an attacker.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product does not properly protect an assumed-immutable element from being modified by an attacker.

Extended description

This occurs when a particular input is critical enough to the functioning of the application that it should not be modifiable at all, but it is. Certain resources are often assumed to be immutable when they are not, such as hidden form fields in web applications, cookies, and reverse DNS lookups.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Lifecycle phase

Architecture and Design

Risk

What does successful exploitation lead to?

Modify Application Data

Affected security scopes: Integrity

Common data types that are attacked are environment variables, web application parameters, and HTTP headers.
Unexpected State

Affected security scopes: Integrity

Defence

How is it prevented and fixed?

Architecture and Design · Operation · Implementation

Defence to apply across several lifecycle phases

Detail
When the data is stored or transmitted through untrusted sources that could modify the data, implement integrity checks to detect unauthorized modification, or store/transmit the data in a trusted location that is free from external influence.