CWE

Trusting HTTP Permission Methods on the Server Side

ID: 650		Date: (C)2012-05-14   (M)2022-10-10
Type: weakness		Status: INCOMPLETE
Abstraction Type: Variant

Description

The server contains a protection mechanism that assumes that any URI that is accessed using HTTP GET will not cause a state change to the associated resource. This might allow attackers to bypass intended access restrictions and conduct resource modification and deletion attacks, since some applications allow GET to modify state.

Extended Description

An application may disallow the HTTP requests to perform DELETE, PUT and POST operations on the resource representation, believing that it will be enough to prevent unintended resource alterations. Even though the HTTP GET specification requires that GET requests should not have side effects, there is nothing in the HTTP protocol itself that prevents the HTTP GET method from performing more than just query of the data. For instance, it is a common practice with REST based Web Services to have HTTP GET requests modifying resources on the server side. Whenever that happens however, the access control needs to be properly enforced in the application. No assumptions should be made that only HTTP DELETE, PUT, and POST methods have the power to alter the representation of the resource being accessed in the request.

Enabling Factors for Exploitation
The application allows HTTP access to resources.
The application is not properly configured to enforce access controls around the resources accessible via HTTP.

Likelihood of Exploit: High

Applicable Platforms
Language Class: All

Time Of Introduction

• Architecture and Design
• Implementation
• Operation

Common Consequences

Scope	Technical Impact	Notes
Access_Control	Gain privileges / assume identity	An attacker could escalate privileges.
Integrity	Modify application data	An attacker could modify resources.
Confidentiality	Read application data	An attacker could obtain sensitive information.

Detection Methods
None

Potential Mitigations

Phase	Strategy	Description	Effectiveness	Notes
System Configuration		Configure ACLs on the server side to ensure that proper level of access control is defined for each accessible resource representation.

Relationships

Related CWE	Type	View	Chain
CWE-650 ChildOf CWE-899	Category	CWE-888

Demonstrative Examples
None

Observed Examples

1. : The HTTP GET method is designed to retrieve resources and not to alter the state of the application or resources on the server side. However, developers can easily code programs that accept a HTTP GET request that do in fact create, update or delete data on the server. Both Flickr (http://www.flickr.com/services/api/flickr.photosets.delete.html) and del.icio.us (http://del.icio.us/api/posts/delete) have implemented delete operations using standard HTTP GET requests. These HTTP GET methods do delete data on the server side, despite being called from GET, which is not supposed to alter state.

For more examples, refer to CVE relations in the bottom box.

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings
None

References:
None