CWE-863: Incorrect Authorization

Abstraction	Structure	Status
None	Simple	Incomplete

Description

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Alternate Terms

AuthZ: “AuthZ” is typically used as an abbreviation of “authorization” within the web application security community. It is distinct from “AuthN” (or, sometimes, “AuthC”) which is an abbreviation of “authentication.” The use of “Auth” as an abbreviation is discouraged, since it could be used for either authentication or authorization.

Nature	ID	View ID	Name
ChildOf	CWE-285	1000	Improper Authorization
ChildOf	CWE-284	1340	Improper Access Control

Background Details

An access control list (ACL) represents who/what has permissions to a given object. Different operating systems implement (ACLs) in different ways. In UNIX, there are three types of permissions: read, write, and execute. Users are divided into three classes for file access: owner, group owner, and all other users where each class has a separate set of rights. In Windows NT, there are four basic types of permissions for files: “No access”, “Read access”, “Change access”, and “Full control”. Windows NT extends the concept of three types of users in UNIX to include a list of users and groups along with their associated permissions. A user can create an object (file) and assign specified permissions to that object.

Modes of Introduction

Phase	Note
Architecture and Design	Authorization weaknesses may arise when a single-user application is ported to a multi-user environment.
Implementation

|Operation| -

Applicable Platforms

Languages

Class: Not Language-Specific

Technologies

Class: None Class: None Class: Not Technology-Specific

Likelihood Of Exploit

High

Common Consequences

Scope	Impact	Note
Confidentiality	Read Application Data, Read Files or Directories	An attacker could bypass intended access restrictions to read sensitive data, either by reading the data directly from a data store that is not correctly restricted, or by accessing insufficiently-protected, privileged functionality to read the data.
Integrity	Modify Application Data, Modify Files or Directories	An attacker could bypass intended access restrictions to modify sensitive data, either by writing the data directly to a data store that is not correctly restricted, or by accessing insufficiently-protected, privileged functionality to write the data.
Access Control	Gain Privileges or Assume Identity, Bypass Protection Mechanism	An attacker could bypass intended access restrictions to gain privileges by modifying or reading critical data directly, or by accessing privileged functionality.
Confidentiality, Integrity, Availability	Execute Unauthorized Code or Commands	An attacker could use elevated privileges to execute unauthorized commands or code.
Availability	DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory), DoS: Resource Consumption (Other)	An attacker could gain unauthorized access to resources on the system and excessively consume those resources, leading to a denial of service.

Detection Methods

Automated Static Analysis

Automated static analysis is useful for detecting commonly-used idioms for authorization. A tool may be able to analyze related configuration files, such as .htaccess in Apache web servers, or detect the usage of commonly-used authorization libraries.

Generally, automated static analysis tools have difficulty detecting custom authorization schemes. Even if they can be customized to recognize these schemes, they might not be able to tell whether the scheme correctly performs the authorization in a way that cannot be bypassed or subverted by an attacker.

Effectiveness: Limited

Automated Dynamic Analysis

Automated dynamic analysis may not be able to find interfaces that are protected by authorization checks, even if those checks contain weaknesses.

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Specifically, manual static analysis is useful for evaluating the correctness of custom authorization mechanisms.

Effectiveness: Moderate

Note: These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules. However, manual efforts might not achieve desired code coverage within limited time constraints.