View source for Caja project

{{Short description|Google project for sanitizing third party HTML, CSS and JavaScript}}
'''Caja''' (pronounced {{IPAc-en|ˈ|k|ɑː|h|ɑː}} {{respell|KAH|hah}})<ref>{{cite web |last1=Mark |first1=Miller |title=Caja discussion on the Caplet Group |url=http://www.eros-os.org/pipermail/e-lang/2007-October/012283.html |website=[cap-talk] |publisher=[e-lang] |archive-url=https://web.archive.org/web/20080517202947/http://www.eros-os.org/pipermail/e-lang/2007-October/012283.html |archive-date=17 May 2008 |url-status=dead}}</ref> was a [[Company:Google|Google]] project for [[HTML sanitization|sanitizing third party HTML]], CSS and JavaScript. On January 31, 2021, Google archived the project due to known vulnerabilities and lack of maintenance to keep up with the latest web security research, recommending instead the [[Software:Google Closure Tools|Closure toolkit]].<ref>{{cite web |title=Introduction - Caja |url=https://developers.google.com/caja/ |website=Google Developers |archive-url=https://web.archive.org/web/20210122083321/https://developers.google.com/caja/ |archive-date=22 January 2021 |language=en |url-status=live}}</ref>

The Caja project was led by Jasvir Nagra with the JavaScript portion designed by Google research scientist [[Biography:Mark S. Miller|Mark S. Miller]] in 2008<ref>{{cite web |last1=Miller |first1=Mark S. |last2=Samuel |first2=M |last3=Laurie |first3=B |last4=Awad |first4=I |last5=Stay |first5=M |title=Safe active content in sanitized JavaScript |url=https://scholar.google.com/scholar?oi=bibs&hl=en&cluster=6783323080761183331 |website=[[Google Scholar]] |date=7 June 2008}}</ref><ref>{{cite web |last1=Synodinos |first1=Dio |title=ECMAScript 5, Caja and Retrofitting Security, with Mark S. Miller |url=https://www.infoq.com/interviews/ecmascript-5-caja-retrofitting-security/ |website=InfoQ |language=en |date=25 February 2011}}</ref> as a JavaScript implementation for "virtual iframes" based on the principles of [[Object-capability model|object-capabilities]]. It would take [[JavaScript]] (technically, ECMAScript 5 strict mode code), [[HTML]], and [[CSS]] input and rewrite it into a safe subset of HTML and CSS, plus a single JavaScript function with no free variables.  That means the only way such a function could modify an object, was if it was given a [[Reference (computer science)|reference]] to the object by the host page.  Instead of giving direct references to DOM objects, the host page typically gives references to wrappers that sanitize HTML, proxy [[URL]]s, and prevent redirecting the page; this allowed Caja to prevent certain [[Phishing|phishing]] and [[Cross-site scripting|cross-site scripting]] attacks, and prevent downloading [[Malware|malware]].  Also, since all rewritten programs ran in the same frame, the host page could allow one program to export an object reference to another program; then inter-frame communication was simply method invocation.

The word "caja" is Spanish for "box" or "safe" (as in a bank), the idea being that Caja could safely contain JavaScript programs as well as being a '''ca'''pabilities-based '''Ja'''vaScript.

Caja was used by [[Company:Google|Google]] in its [[Software:Google Apps Script|Google Apps Script]]<ref>{{cite web |title=Html Service: Caja Sanitization |url=https://developers.google.com/apps-script/guides/html-service-caja |website=Google Developers |archive-url=https://web.archive.org/web/20130826134554/https://developers.google.com/apps-script/guides/html-service-caja |archive-date=26 August 2013 |url-status=dead}}</ref> products. In 2008 MySpace<ref>{{cite web |title=MySpace: Caja JavaScript scrubbing ready for prime time |url=http://blogs.zdnet.com/security/?p=847 |archive-url=https://web.archive.org/web/20081001192140/http://blogs.zdnet.com/security/?p=847 |archive-date=1 October 2008 |date=4 February 2008}}</ref><ref>{{cite web |title=Web 2.0 Investors: Pay Attention To Caja |url=https://due-diligence.typepad.com/blog/2008/04/web-20-investor.html |website=Tim Oren's Due Diligence |date=11 April 2008}}</ref> and [[Company:Yahoo!|Yahoo!]]<ref>{{cite web |last1=Pullara |first1=Sam |title=OpenSocial API Blog: Launched: Yahoo!'s First Implementation of OpenSocial Support |url=http://opensocialapis.blogspot.com/2008/10/launched-yahoos-first-implementation-of.html |publisher=[[Software:OpenSocial|OpenSocial]] |archive-url=https://web.archive.org/web/20081216015012/http://opensocialapis.blogspot.com/2008/10/launched-yahoos-first-implementation-of.html |archive-date=16 December 2008 |date=28 October 2008 |url-status=dead}}</ref> had both deployed a very early version of Caja.

== See also ==
* [[Joe-E]], an object-capability subset of [[Java (programming language)|Java]]
* [[E (programming language)|E]]

== References ==
{{Reflist|30em}}

== External links ==
* [http://developers.google.com/caja/ Caja project home page]
* [http://code.google.com/p/google-caja/ Caja project source code]
* [https://web.archive.org/web/20100301172309/http://caja.appspot.com/ Caja playground]
* [https://web.archive.org/web/20080827170042/http://google-caja.googlecode.com/files/caja-spec-2008-06-07.pdf Caja draft specification]: "Safe active content in sanitized JavaScript", [[Biography:Mark S. Miller|Mark S. Miller]], Mike Samuel, Ben Laurie, Ihab Awad, Mike Stay
* [http://www.metablocks.com/blog/2009/06/29/yahoogoogle-caja-javascript-sandbox Yahoo!/Google Caja Javascript Sandbox]

{{Object-capability security}}
{{ECMAScript}}

{{DEFAULTSORT:Caja Project}}
[[Category:Capability systems]]
[[Category:Transformation languages]]

{{Sourceattribution|Caja project}}