2012/11/30

OWASP BeNeLux 2012: Secure Web Integration Patterns in the Era of HTML5 - John Wilander

Old / classic web integration patterns to avoid same-origin restrictions: do NOT use it anymore (security / manageability issues)
  • crafted <img /> tag
  • JSONP (Json "Padding")
    • JS wiring of 2 domains with callback
    • JQuery calls JSONP "Crossdamain
    • blind trustassociation
    • check the origin
  • document.domain
    • change in both script providers to same common part
New HTML5 web integration patterns:
  • CORS: Cross Origin Resource Sharing
    • Ajax + header: Access-Control-Allow-Origin: allowed.domain.com
    • explicit cookie sharing with xhr.withCredentials = true
    • special headers:
      • setRequestHeader
      • ! check "origin" header on servers (whitelist based)!
  • Sandboxed iframe
    • iframe tag +  sandbox
    • optional & explicit features: allow-same-origin, allow-scripts, allow-forms
    • ideal to isolate legacy web apps, even served from the same domain
  • postMessage:
    • textbased message channels between 2 domains
    • whitelist checks
    • keep handle of windows -> communiction between windows (tabs...)
    • combine postMessage + sandboxed IFrames to integrate legacy webapps with new HTML5 apps: limits risks to iframe.
Demo's: OWASP One-Liners
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