Modification of Assumed-Immutable Data (MAID)
Draft Base
Structure: Simple
Description
The product does not properly protect an assumed-immutable element from being modified by an attacker.
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.
Common Consequences 2
Scope: Integrity
Impact: Modify Application Data
Common data types that are attacked are environment variables, web application parameters, and HTTP headers.
Scope: Integrity
Impact: Unexpected State
Potential Mitigations 1
Phase: Architecture and DesignOperationImplementation
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.
Demonstrative Examples 1
In the code excerpt below, an array returned by a Java method is modified despite the fact that arrays are mutable.
Code Example:
Bad
Java
javaObserved Examples 2
CVE-2002-1757Relies on $PHP_SELF variable for authentication.
CVE-2005-1905Gain privileges by modifying assumed-immutable code addresses that are accessed by a driver.
Applicable Platforms
Languages:
Not Language-Specific : Undetermined
Modes of Introduction
Implementation
Architecture and Design
Related Attack Patterns
Related Weaknesses
Taxonomy Mapping
- PLOVER
Notes
RelationshipMAID issues can be primary to many other weaknesses, and they are a major factor in languages that provide easy access to internal program constructs, such as PHP's register_globals and similar features. However, MAID issues can also be resultant from weaknesses that modify internal state; for example, a program might validate some data and store it in memory, but a buffer overflow could overwrite that validated data, leading to a change in program logic.
TheoreticalThere are many examples where the MUTABILITY property is a major factor in a vulnerability.