RIA and Ajax Security Workshop – Web 2.0 Expo Berlin

A very interesting and informative talk dealing with the new types of attacks that affect web 2.0 applications and RIA in particular.

The session was divided in 2 parts, the first about AJAX and the last about Rich Internet Applications.

The slides of this talk are available on slideshare and are impressive for their completeness. Not only they provide detailed examples for every case illustrated, but they link to a series of articles and web resources.

The main problem of this talk is that it’s quite impossible to be able to be specific enough and, at the same time, don’t get too much into details. This resulted in some hard-to-understand parts.

AJAX

In general attacking an AJAX application is more difficult compared to a web 1.0 site. But on the other hand is more difficult to protect an AJAX application because there are more ways to exploit it and new ways are discovered every day.

  • Not all “web 2.0” sites use new technologies (such as Youtube and MySpace)
  • A single page in Myspace has a lots of includes.
  • Also Google Maps has a lot of includes, but ofJavascript code. Google code can be potentially insecure

Why care about web 2.0 security

  • People changed how they interact with web sites (they erase privacy barriers and they don’t feel the distance. The are the new generations)
  • Technologies spread from innovators to traditionalists (today AJAX in financial institutions, health care, government) – mainstream
  • Bugs are affecting people now

Discovery and method manipulation

  • Playing with parameters is still an excellent web attack (asking application to do the work for you). As business logic gets more complex, so do parameters vulnerabilities
  • Figuring out web apps is tough part of pen-test

Two types of Ajax apps

  • client-server proxy (equivalent to SOAP, client hides javascript)
  • client-side rendering (we can see the javascript and know what it does)

Cross Site Scripting

  • Downstream communication methods are much more complicated
  • User controlled data might be contained in arguments in dynamically created javascript, contained in Javascript arrays, etc. As a result, attack and defence is more difficult

Four bugs

  • downstream JS Arrays. Dangerous characters
  • XSS payload can be tucked into many places
  • XSS might already be in the dom (document.url, document.location, document.referer).
  • AJAX uses “backend” requests never expected to be seen directly in browser

RIA

Is ill-defined. Many contain many terms, AJAX, Flash, offline mode, decoupling from the browser. There is a huge disparity in features and security design.

Why use RIA

  • to increase responsiveness
  • desktop integration
  • to write full desktop apps

RIA Frameworks

No one framework is without limits and security problems. The worst seems Adobe Air because it shows all the limits of the very old ActiveX model.

The frameworks:

  • Adobe AIR
  • Microsoft Silverlight
  • Google Gears
  • Mozilla Prism

Adobe Air

  • Full-featured
  • Cross-browser, cross-platform
  • Created with Flex, Flash
  • Can be invoked by browser with arguments, like ActiveX or Flash
  • Air is best thought as ActiveX than Flash ++ (code runs with full privileges and can install malware)
  • SWF files can import functionalities that allows them to interact with AIR applications
  • SWF files can check install status and version
  • By default, code included in AIR application has full rights
  • There is not a “code access security” model such as in Java or .Net
  • AIR has many ways of loading executable content to run, such as HTML/JS and SWF
  • AIR applications can be bundled as binaries
  • Problems: allowing users to install signed applets is dangerous. Allowing self-signed is terrifying
  • Some suggestions to adobe: change default action, disable unsigned install prompts

Silverlight

Lot of sensibility toward security

  • Is the Microsoft Flash equivalent
  • Cross browser and cross platform
  • Subnet of the .NET frameworks
  • The security model is based on .NET
  • Calling system primitives the system will fail. You need to isolate it
  • What could go wrong (threading, DoS attacks against local system)

Google Gears

  • Has SQLite embedded
  • Uses an homegrown API for synchronizing data
  • Has a LocalServer
  • Works offline via SQL database, local assets and a local app server
  • Uses some origin to restrict access to site databases and LocalServer resource capture
  • Provides for parametrized SQL
  • Unfortunately they allows personalization of opt-in screen

Yahoo! Browserplus

  • A very bad idea
  • Runs as a browser plugin, with a separate helper process
  • It’s very similar to ActiveX concepts
  • Use old version or Ruby. Perfectly safe as long as you don’t use strings and arrays

Mozilla Prism

  • Wraps webapps to appears as desktop apps
  • Standalone browser instance
  • Problem: the Javascript included with webapps has full XPCOM privileges (but no content scripting privileges)
  • Problem: the sandbox isn’t real

HTML 5

HTML introduces some new concepts related to storage of informations.

  • Introduces DOM storage (sessionStorage, localStorage, database storage)
  • The major goals are more storage space and real persistence, because cookies are considered too small and users delete cookies or won’t accept them
  • This method bypasses pesky users, that however can use a specific about:config directive

Browser based SQL Databases

  • Injection becomes far more damaging (because of lot of privileges)

Checklist

  • prevent predictability named data stores
  • parametrize sql statements

Summary

  • RIA frameworks widely vary in their security models
  • It is highly likely that web developers will introduce interesting flaws into their desktop applications
Alex Stamos is a Founding Partner of iSEC Partners, Inc, a strategic digital security organization. Alex is an experienced security engineer and consultant specializing in application security and securing large infrastructures, and has taught multiple classes in network and application security. He is a leading researcher in the field of web application and web services security and has been a featured speaker at top industry conferences such as Black Hat, CanSecWest, DefCon, SyScan, Microsoft BlueHat and OWASP App Sec. He is a contributing author of “Hacking Exposed: Web 2.0” and holds a BSEE from the University of California, Berkeley.

Dion Almaer (ajaxian.com)- Hot to take your app offline

Dion parla di Google Gears, la tecnologia che permette di portare offline dati e applicazioni web.

Parte dalla considerazione che in Palo alto si perde la connettività molto spesso. Portare l’applicazione offline può eliminare delle barriere, ma non solo. Portare le elaborazioni offline permette anche di aumentare la performance per l’online.

A Google si sono chiesti come portare le applicazioni offline senza risovere semplicemente i problemi di Google stessa; per questo Google Gears è stato rilasciato come open source (new bsd).

La filosofia su cui si basa può essere così sintetizzata:

  • usare lo stesso URL per applicazione online e offline
  • la transizione la versione online e offline dell’applicazione deve essere trasparente
  • dev’essere possibile usare dati locali anche se si è online
  • dev’essere disponibile a tutti su tutte le piattaforme

Google Gears è qualcosa di più rispetto a Ajax, ma i concessi sono tra loro simili: si tratta di fare per le applicazioni offline quello che XMLHttpRequest fa le per applicazioni web (per questo è simile, come concezione, a Ajax).

I componenti:

  1. LocalServer: che gira nel browser
  2. Database: un database relazionale “fully-searchable”, non file di testo
  3. WorkerPool: possibilità di gestire thread indipendenti dal browser

Database

Il database è creato usando SQLite. Su questa base sono stati aggiunti dei livelli di astrazione successivi.

GearsORM: gestire relazione tra oggetti del database come fosse Hibernate.

GearShift: gestire la migrazione di tanti database negli utenti quando si fanno cambiamenti: db migration come il rails.

Local Server

E’ semplicemente un mini server web che ascolta sulla porta 200 e 304.

Worker Pool

Risponde alla necessità di avere diversi thread di processo separati dal browser, e sicuri. In questo modo il Javascript gira in background, non nel contesto del browser.

Altro

E’ stata scritta un’estensione per criptare i dati salvati nel client. E’ stato aggiunta la ricerca full-text.

Questo intervento è stato scritto in live blogging dalla conferenza Future of Web Apps di Londra, il 3 e 4 Ottobre 2007. Leggi tutti gli interventi di Fucinaweb dal FOWA