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The Bank Job Utilizing XSS Vulnerabilities

The Bank Job Utilizing XSS Vulnerabilities. Adi Sharabani IBM Rational Application Security Research Group Manager. OWASP IL. Agenda. Theoretical part: Same Origin Policy 101 Cross-Site Scripting 101 HTTP sessions Practical part: Trivial robbery Advanced robbery.

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The Bank Job Utilizing XSS Vulnerabilities

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  1. The Bank JobUtilizing XSS Vulnerabilities Adi Sharabani IBM Rational Application SecurityResearch Group Manager OWASP IL

  2. Agenda • Theoretical part: • Same Origin Policy 101 • Cross-Site Scripting 101 • HTTP sessions • Practical part: • Trivial robbery • Advanced robbery

  3. Browser Scripting Capabilities • What can scripts do: • Scripts can perform user interactions with the site • Scripts can seamlessly interact with the web site • Can perform any action that is related to the site • Can launch signed and safe ActiveX control

  4. Scripting Restrictions – Same Origin Policy • What scripts can not do: • Scripts can only interact with the domain they came from • Scripts can see send and receive responses only from their domain • Scripts can access other browser’s frames only from same domain • Scripts can issue requests to other domains (but not view the corresponding responses)

  5. XSS 101 • XSS occurs when user input (JavaScript) is returned by the web application: String data = request.getParameter(“param”); out.println(data) • Simple exploit: • http://www.thebank.site/action?param=<payload> • XSS breaks Same-Origin Policy • Vulnerable domain may now return arbitrary JavaScripts.

  6. 1 Link to bank.com sent to user via E-mail or HTTP User sends script embedded as data 2 3 Script returned, executed by browser Cross Site Scripting – The Exploit Process Evil.org User TheBank.site

  7. The session cookie • HTTP is stateless • Session id makes your application stateful • Session id = your identification • Should not be guessable • JavaScript access: document.cookie

  8. Evil.org uses stolen session information to impersonate user Script sends user’s cookie and session information without the user’s consent or knowledge 1 Link to bank.com sent to user via E-mail or HTTP 5 4 User sends script embedded as data 2 3 Script returned, executed by browser Cross Site Scripting – The Exploit Process Evil.org User TheBank.site

  9. Trivial Robbery Demo

  10. Demo • Build payload • Send malicious link to victim • Retrieve the cookie and extract the session id • Manually add session cookie to local browser • Make a transaction

  11. Advanced Robbery Demo

  12. Problems: The session id cookie is not enough • HTTPOnly • Set-Cookie: <name>=<value>[; <name>=<value>] [; expires=<date>][; domain=<domain_name>] [; path=<some_path>][; secure][; HttpOnly] • Pre-logon XSS

  13. Problems: Key-logging is not enough • Second factor authentication • Dongles • Client certificates • Challenge on transaction • Security questions: “What is your mom’s maiden name?” • Time-based challenge

  14. ? http://blog.watchfire.com

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