Trust Boundary Violation
Weakness ID: 501 (Weakness Base)Status: Draft
+ Description

Description Summary

The product mixes trusted and untrusted data in the same data structure or structured message.

Extended Description

By combining trusted and untrusted data in the same data structure, it becomes easier for programmers to mistakenly trust unvalidated data.

+ Time of Introduction
  • Architecture and Design
+ Applicable Platforms



+ Demonstrative Examples

Example 1

The following code accepts an HTTP request and stores the username parameter in the HTTP session object before checking to ensure that the user has been authenticated.

(Bad Code)
Example Language: Java 
usrname = request.getParameter("usrname");
if (session.getAttribute(ATTR_USR) == null) {
session.setAttribute(ATTR_USR, usrname);
(Bad Code)
Example Language: C# 
usrname = request.Item("usrname");
if (session.Item(ATTR_USR) == null) {
session.Add(ATTR_USR, usrname);

Without well-established and maintained trust boundaries, programmers will inevitably lose track of which pieces of data have been validated and which have not. This confusion will eventually allow some data to be used without first being validated.

+ Other Notes

A trust boundary can be thought of as line drawn through a program. On one side of the line, data is untrusted. On the other side of the line, data is assumed to be trustworthy. The purpose of validation logic is to allow data to safely cross the trust boundary--to move from untrusted to trusted. A trust boundary violation occurs when a program blurs the line between what is trusted and what is untrusted. The most common way to make this mistake is to allow trusted and untrusted data to commingle in the same data structure.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class485Insufficient Encapsulation
Development Concepts (primary)699
Seven Pernicious Kingdoms (primary)700
Research Concepts (primary)1000
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsTrust Boundary Violation
+ Content History
Submission DateSubmitterOrganizationSource
7 Pernicious KingdomsExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Demonstrative Example, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Description, Relationships, Other Notes, Taxonomy Mappings