XSS- an application security vulnerability
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One of the most typical web application security vulnerabilities Cross-Site Scripting (XSS). What does it mean to Developer? How they are important? What should we keep in mind? How could we prevent this to some extend as Developer? How Attackers proceed? Many mores..
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XSS- an application security vulnerability
- 1. XSS (Cross-Site Scripting) - An application security vulnerability from Developers point of view Soumyasanto Sen, #sitMUC @soumyasanto
- 2. Wikipedia says "XSS enables attackers to inject client-side script into web pages viewed by other users". OWASP(the free and open software security community) says "Cross-Site Scripting attacks are a type of injection problem, in which malicious scripts are injected into the otherwise benign and trusted web sites." "An XSS attack occurs when a script from an untrusted source is executed in rendering a page" #sitMUC Definition
- 3. #sitMUC What is XSS? Client side vulnerability but can Server side one. Based on injection through JavaScript, VBScript, Flash, HTML, JSON, ActiveX etc. Due to insufficient validation and sanitization. Attacker’s Paradise Stealing Credentials, Private Info. Execute commands (CSRF), malicious scripts Redirection to malicious site Port Scanning, Phishing, Keylogging etc.
- 5. #sitMUC According to latest White-hat Security report, 47% of web applications have XSS vulnerability Why XSS?
- 6. #sitMUC According to Google Vulnerability Reward Program's Statistics, XSS is the most reported issue Why XSS?
- 7. #sitMUC According to "Open Sourced Vulnerability Database" XSS is at #1 Why XSS?
- 8. #sitMUC TrustWave Global Security Report says XSS is again the highest Why XSS?
- 9. #sitMUC No Monkey Testing Example: Based on Testing
- 10. Injection Points: Through which the Attacker can enter or injects scripts Insert /Edit Text Insert/Edit Image Insert/Edit URL Set Attributes Insert/Upload File Insert/Upload Video What is Context? Context is an environment where user-supplied input or input from other application(s) eventually ends-up or starts living. “Context Is King for All Areas of IT Security” #sitMUC Example: Based on Testing (Definitions)
- 11. #sitMUC http://www.ea.com/search?q=“XYZ Example: Based on Testing (Contexts)
- 12. #sitMUC http://www.ea.com/search?q=“JUNK Example: Based on Testing (Contexts)
- 13. #sitMUC http://search.health.com/results.html?Ntt=xxxxxxxxxx Single Quotes Case Double Quotes Case Example: Based on Testing (Contexts)
- 14. #sitMUC https://www.froala.com/wysiwyg-editor Example: Based on Testing (Contexts)
- 15. #sitMUC Example: Based on Testing (Contexts)
- 16. #sitMUC Example: Based on Testing (Summary of Contexts)
- 17. #sitMUC ATTACK METHODOLOGY • Systematic in nature • Easy to understand • Context-Specific • Attack methodology is `complete` and one can guarantee that there is an XSS or no XSS in a particular injection point. • With the help of attack methodology, one can make a secure per-context XSS sanitizer • Can be applied to other server-side languages Example: Based on Testing (Attack Methodology)
- 18. #sitMUC SCRIPT CONTEXT ATTACK METHODOLOGY Example: Based on Testing (Attack Methodology) Demo http://jsfiddle.net/4eqK4/5/
- 19. #sitMUC ATTRIBUTE CONTEXT ATTACK METHODOLOGY Example: Based on Testing (Attack Methodology) Demo http://www.drudgereportarc hives.com/dsp/search.htm http://jsfiddle.net/9t8UM/3/
- 20. #sitMUC STYLE CONTEXT ATTACK METHODOLOGY Example: Based on Testing (Attack Methodology)
- 21. #sitMUC URL CONTEXT ATTACK METHODOLOGY Example: Based on Testing (Attack Methodology)
- 22. #sitMUC <a href="url">link text</a> <a href=javascript:alert(1)>link text</a> <img src="pic_mountain.jpg"> <img src=javascript:while(1){}> Example: Based on Testing (Attack Methodology)
- 23. #sitMUC Encoding will not help in breaking the script context unless developers are doing some sort of explicit decoding. Example: Based on Testing (Attack Methodology)
- 24. #sitMUC Two arrays of black-listed keywords Other names filterXSS and noXSS Example: Based on Testing (Customized XSS Solutions)
- 25. #sitMUC Two arrays of black-listed keywords Example: Based on Testing (Customized XSS Solutions) Bypass: <img src=x id=confirm(1) onerror=eval(id)
- 26. #sitMUC The goal of this function is to stop JavaScript execution via style. Example: Based on Testing (Customized XSS Solutions) Bypass: width:expression(al ert(1))
- 27. #sitMUC Example: Based on Testing (Customized XSS Solutions) Another popular customized XSS protection solution
- 28. #sitMUC Example: Based on Testing (Summary of Bypasses)
- 29. #sitMUC Example: Based on Testing (Real Solutions)
- 30. #sitMUC Example: Based on Testing (Real Solutions) Protection against JavaScript execution via `url` e.g., img'ssrc and/or anchor's href attribute Implementation of `urlContextCleaner()`
- 31. #sitMUC Example: Based on Testing (Solutions -Make it Simple) WYSIWYG What You See Is What You Get · Forum Post · Private Messaging · Wiki Post · Support Ticket · Signature Creation · Comments
- 32. #sitMUC Example: Based on Testing (Solutions -Make it Simple) WYSIWYG What You See Is What You Get
- 33. #sitMUC Example : Based on Real (Bypassing) ABAP Case Study:
- 34. #sitMUC Demo: Based on Games (Bypassing) https://xss-game.appspot.com/ http://xssplaygroundforfunandlearn.netai.net/series1.html https://html5sec.org/innerhtml/ (Mario Heiderich's Utility)
- 36. XSS (Cross Site Scripting) Prevention Cheat Sheet from OWASP (HTML5 Security Clean Sheet) Validation on XSS Input. Use White-Listing, Escaping and sanitization method. (Use Sanitizers) “Do not trust anything ever, specially when it comes to user input” Understanding common browser behaviors that lead to XSS Learning the best practices for your technology #sitMUC Preventions
- 37. #sitMUC Latest News Salesforce plugs silly website XSS hole, hopes nobody spotted it (Mid August) Critical PayPal XSS vulnerability left accounts open to attack (Late August) eBay Fixes XSS Flaw in Subdomain (Early September) Netflix Sleepy Puppy Awakens XSS Vulnerabilities in Secondary Applications (Early September) Attackers exploit vulnerabilities in two WordPress plugins (Early May)
- 38. #sitMUC Latest News 0-day XSS vulnerability on SAP website put customers’ data at risk of theft by hackers (Early May) SAP HANA Databases Vulnerable to XSS and SQL Injections (Late June) Overall: Almost ALL websites have serious security vulnerabilities, study shows
- 39. Lack enough Pen. Test ( 92% of the respondents perform penetration testing. 21% perform it annually, 26% perform it quarterly and 8% never perform penetration testing.) Taking responsibility from the Developers Unawareness of XSS vulnerability Not taking seriously #sitMUC Challenges
- 40. XSS is unavoidable at least nowadays ! Now its your job to raise the bar for attacker. “XSS is Everywhere” (Short and Simple) Use Prevention, Go for Solutions in the forms of layers, Keep Updated & Do regular Penetration Testing #sitMUC Conclusion
- 41. #sitMUC Learning
- 42. Thank You Soumyasanto Sen @soumyasantoDr. Ashar Javed : http://slides.com/mscasharjaved/