CWE-285: Improper Authorization

Abstraction	Structure	Status
None	Simple	Draft

Description

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.

Extended Description

Assuming a user with a given identity, authorization is the process of determining whether that user can access a given resource, based on the user’s privileges and any permissions or other access-control specifications that apply to the resource.

When access control checks are not applied consistently - or not at all - users are able to access data or perform actions that they should not be allowed to perform. This can lead to a wide range of problems, including information exposures, denial of service, and arbitrary code execution.

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-284	1000	Improper Access Control
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
Implementation

|Architecture and Design|

|Operation| -

Applicable Platforms

Languages

Class: Not Language-Specific

Technologies

Class: None Class: None

Likelihood Of Exploit

High

Common Consequences

Scope	Impact	Note
Confidentiality	Read Application Data, Read Files or Directories	An attacker could read sensitive data, either by reading the data directly from a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to read the data.
Integrity	Modify Application Data, Modify Files or Directories	An attacker could modify sensitive data, either by writing the data directly to a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to write the data.
Access Control	Gain Privileges or Assume Identity	An attacker could gain privileges by modifying or reading critical data directly, or by accessing insufficiently-protected, privileged functionality.

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. In addition, the software’s design may include some functionality that is accessible to any user and does not require an authorization check; an automated technique that detects the absence of authorization may report false positives.

Effectiveness: Limited

Automated Dynamic Analysis

Automated dynamic analysis may find many or all possible interfaces that do not require authorization, but manual analysis is required to determine if the lack of authorization violates business logic

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.