This charter has been superseded as a result of Advisory Committee Review; please see the revised charter.

Web Application Security Working Group Charter

The mission of the Web Application Security Working Group, part of the Security Activity, is to develop security and policy mechanisms to improve the security of Web Applications, and enable secure cross-site communication.

Join the Web Application Security Working Group.

End date 31 March 2015
Confidentiality Proceedings are public
Chairs Brad Hill, Dan Veditz
Team Contacts
(FTE %: 10)
Wendy Seltzer
Usual Meeting Schedule Teleconferences: Weekly
Face-to-face: 1-2 annually


Modern Web Applications may be governed by numerous security policies which are documented in a number of specifications, including HTML5 and XMLHttpRequest. Unfortunately, these policies are not implemented uniformly across major web browsers and plugins, and are inadequate for certain use cases. Because there is no standard, shared mechanism for declaring and enforcing policies it is not possible for sites to selectively declare the need to escape from some restrictions or to request enforcement of additional restrictions.

These issues are especially relevant for the many web applications which incorporate other web application resources (mashups). That is, they comprise multiple origins (i.e., security principals).

Areas of scope for this working group include:

Attack Surface Reduction

The WG will design mechanisms to allow applications to restrict or forbid potentially dangerous features which they do not intend to use, thus limiting the attack surface.

Secure Mashups

Several mechanisms for secure resource sharing and messaging across origins exist or are being specified, but several common and desirable use cases are not covered by existing work, such as: allowing child IFRAMEs to protect themselves from "clickjacking" or specify what characteristics a parent window must allow. The WG will design mechanisms and coordinate with existing and ongoing work in other forums to allow secure mashups.


The coarse-grained nature of security principals (origins) in web application security policies, (e.g. the Same Origin Policy) means that a security weakness in any origin's web application resources may create vulnerabilities for all web application resources of that origin, as well as for any other origins whose web applications interact with it. Mechanisms which require individual declaration at every resource or element are impractical for large scale sites, and also unsuitable for legacy applications not under active maintenance. Web application administrators should have available a small number of uniform policy control points from which to manage these risks.

The Web Application Security (WebAppSec) Working Group will develop a policy mechanism providing web application administrators a standardized means for security policy declaration, based on the existing Content Security Policy specification.

The WebAppSec Working Group also will develop a recommendation to enable secure, cross-origin applications, as joint work with the Web Applications Working Group, based on the current Cross Origin Resource Sharing specification.

The Web Application Security Working Group may provide review of specifications from other Working Groups, in particular as these specifications touch on chartered deliverables of this group (in particular CSP), or the Web Security model.

Success Criteria

To advance to Proposed Recommendation, each specification is expected to have two independent implementations of each feature described in the specification.


All of the following deliverables are on the Recommendation Track:

Content Security Policy 1.0 (CR)
Content Security Policy 1.1 (WD)

A policy language intended to enable web designers or server administrators to declare web application content security policy. The goal of this specification is to reduce attack surface by specifying overall rules for what content may or may not do, thus preventing violation of security assumptions by attackers who are able to partially manipulate that content.

Cross-Origin Resource Sharing (CR)

Advance existing recommendation-track documents specifying mechanisms necessary for secure mash-up applications, based on the existing CORS specification. Such recommendations will be published as joint work with the Web Applications Working Group.

Secure Cross-Domain Framing: User Interface Security Directives for Content Security Policy (WD)

Create and advance existing recommendations specifying bi- directional parent/child policies to enable secure mash-up applications built around cross-domain framing. To express necessary constraints and demands, this deliverable will re-use and extend the policy language of the Content Security Policy deliverable with the goal of creating uniform semantics for requirements currently disjoint in expression and implementation across the CSP, the HTML5 IFRAME sandbox, and the X-Frame-Options HTTP header. This work will be closely coordinated with the IETF websec WG and other frame policy related work in the IETF in order to avoid overlapping or conflicting specifications.

Secure Mixed Content

Create and advance recommendation(s) for dealing with resources loaded over insecure channels in a secure web application. Use cases include:

  • Adding integrity protections to sub-resource loads from HTML documents. This mechanism would have the goals of allowing resource authors to specify the exact hash value of cross- origin sub-resources and/or to allow optimistic loading of such resources in a cache-friendly manner over insecure transports. This work would be coordinated with and possibly be a joint deliverable with the HTML WG.
  • Standard behaviors for user agents to follow when encountering insecure resource loads in a secure context. This might include definitions of “active” and “passive” content that must be blocked or can be loaded with a warning, and possibly ways for secure applications to consume insecure but non-sensitive resources (such as a weather feed).
Lightweight Isolated / Safe Content

Create and advance recommendation(s) for lightweight isolation and safety mechanisms for composed web applications. An iframe used with postMessage can provide a strong isolation barrier, but, for some scenarios, requires too many resources on the client and presents an unfriendly API to developers. The deliverable(s) will describe mechanisms to compose applications from imported components while isolating the application from malicious impacts of those components. Possible mechanisms include sandboxing and/or safe sub-setting of ECMAScript or HTML.


Note: The group will document significant changes from this initial schedule on the group home page.
Specification FPWD LC CR PR Rec
Content Security Policy

October 2013
December 2013
CSP 1.1
October 2013 December 2013 February 2014 April 2014
Secure Cross-Domain Resource Sharing (CORS)
September 2013 December 2013
UI Security Directives for CSP
October 2013 December 2013 February 2014 April 2014
Secure Mixed Content
October 2013 January 2014 March 2014 May 2014 July 2014
Lightweight Isolated Content
October 2013 January 2014 March 2014 May 2014 July 2014

Dependencies and Liaisons

W3C Groups

Web Applications Working Group
This Working Group will develop its secure cross-site resource sharing deliverable as joint work with the Web Applications Working Group.
HTML Working Group
The HTML5 specification defines many of the security policies that apply in the current browser environment.
Device API Working Group
The Device API Working Group's deliverables include an API for requesting and managing user permissions to use device features.

Outside Groups

IETF WebSec Working Group
The IETF Web Security WG is chartered to provide a Web Security problem statement and standardize a limited number of selected specifications. This Working Group is expected to liaise and collaborate closely with the WebSec Working Group. Coordination is, in particular, expected with respect to the secure cross-domain framing deliverable proposed in this charter, and ongoing work to document the X-Frame-Options mechanism within the IETF.
ECMA Technical Committee 39 (TC39)
This is the group responsible for ECMAScript standardization, and related ECMAScript features like E4X.


To be successful, the Web Application Security Working Group is expected to have 10 active participants for its duration. Effective participation to Web Application Security Working Group is expected to consume one day per week for chairs and editors. The Web Application Security Working Group will allocate also the necessary resources for building Test Suites for each specification.


This group primarily conducts its work on the public mailing list public-webappsec@w3.org (archive).

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the Web Application Security Working Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

About this Charter

This charter for the Web Application Security Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

Please also see the previous charter for this group.


Brad Hill, Dan Veditz, Wendy Seltzer <wseltzer@w3.org>

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