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Unleashing Fuzzing: Strategies and Techniques for Security Testing

Join Iñaki Rodríguez, a seasoned security manager, as he dives deep into the world of fuzzing. Learn how to make applications and networks fail by feeding them various inputs, exploring real vulnerabilities and common issues. Discover the tools and methodologies needed for effective fuzz testing, from unpackers and debugging utilities to automation and data inventory. Understand the importance of a security development lifecycle (SDL) and grasp the significance of responsible disclosure in security practices. Equip yourself with knowledge to protect your software better.

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Unleashing Fuzzing: Strategies and Techniques for Security Testing

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Presentation Transcript

  1. Show me your Kung Fuzz No Con Name2011 @virtualminds_es / irodriguez at virtualminds.es

  2. Whoisthisguy? • Iñaki Rodríguez • CISSP, CEH • Security Manager at Ackstorm S.L.

  3. Aboutfuzzing • Attempting to cause a program or network to fail by feeding it randomly (or not so) generated data. • Generate a lot of craptocrashanapplication.

  4. Targets • Understandthemostbasicconcepts of fuzzing • Complexity vs Knoweldge • Notyourbussines • Real vulnerabilities • Commonissues

  5. WhyweFuzz • Wedon’t trust our software • Wedon’t trust ourproviders software • $$$ or €€€ • CorporateImage

  6. SDL (securitydevelopmentlifecycle)

  7. THE lab (I) • Virtual Servers • Lot of memory • Fasthard disk (SSD) • Snapshotshelpstorevert

  8. THE lab (II) • Physical Servers • Old Hardware • More isbetter • Youlostsnapshots • Butyouhavedeepfreezeand fssnapshots

  9. Software • Unpackers (upx, aspack, *lordpe, *importRec, PeID …) • (Un)Compressors (7zip) • Sysinternal suite • Api Monitor • InterpretedLanguages (perl y python) • Debuggers(gdb, radare, ImmunityDebugger, Olly, …) • Decompilers (Ida Free, Ida Pro $$$ y theother)

  10. Some FUZZERS

  11. process

  12. Choosingtheapplication

  13. inventory • CMDB • Nmap (-sV) • OcsInventory • Repositories

  14. Automatinginventory • Database • CPE Normalization • Stats (use, vulnerabilities, …) • Informationfromoutside (securitylists, osvdb, nvd, …) • Scripting isyourfriend

  15. Clasificationcriteria • Qualitative • Vulnerabilitiesimpact • Complexity • Widelyused • Personal preferences • Cuantitative • Number of installations • Number of knownvulnerabilities • Assetvalue • Visibility (local, remote) • Number of threats (none, few, many)

  16. modeling

  17. FuzzingModels • Mutation (Dumbfuzzing) • Generation (Smart fuzzing)

  18. Mutationmodel

  19. Generationmodel

  20. Generationmodel

  21. Knowyourenemy • Whatkind of applicationis? • Network Services • Web Applications • Libraries • ActiveX • Whatkind of inputs? • Command Line • Files • Network • Forms • Environment Variables • Url • …

  22. Files (I) • Ifwe are lucky, previouslydocumented • www.wotsit.org • www.fileformat.info • 010 Editor / Hexedit / Others. • Ifnotdocumented • Throughvalid files repository • Google – ext:svg • Bing – type:svg • Reverse engineering

  23. Files (II) • SomeinterestingAPIs • CreateFile / CloseHandle / open / close • Lseek • WriteFile / ReadFile / write / read

  24. Files (III) eax=00000000 cmpwordptr [eax+edx*2],0ffffh

  25. Network services (I) • Open protocols (RFC) • Sniffingtrafficbetweenclient and server • Whataboutclients? • Frompcaptomodel

  26. Network services (II)

  27. DEMO I – Network Services • ACTFAX FTP SERVER • Video: http://www.youtube.com/watch?v=yOKVIgZso4M • Python • Sulley • Paimei

  28. Libraries (I) • Probablywelldocumented • “Hidden” api • Exported symbols • Argumentsguessing

  29. Libraries (II)

  30. DEMO II – LIBRARY • ASPEMAIL • Video: http://www.youtube.com/watch?v=7DxXiChy_Oc • Perl • Vbscript • Do ityourself • Windbg

  31. Active x (I) • Probablywelldocumented • Internet Explorer only • ActiveX Interfaces • AxMan / Comraider

  32. Active X (II)

  33. Web applications (I) • Lot of documentation • Notonlyurl (Headers, cookies, methods,…) • Ajax / Javascript / Apptesting • OWASP

  34. Web applications (II)

  35. Commonproblems • Encryption • Checksum • Unknownformat/protocol/whatever • Relations • Conditions • Codecoverage

  36. Testing

  37. fuzzingstages

  38. AND nowwhat? • Responsibledisclosure • Sellit • Exploit • Patch (binaryorsource) • Full disclosure • IDS signature

  39. Improvements • Parallelprocessing • Modifiedapplication • In-memoryfuzzing • Reversingskillsneeded • Codecoverage

  40. In memoryfuzzing Breakpoint sub_0xC0FF33 Takesnapshot Change input Input interaction Exception? Jumptosnapshot Restoresnapshot End sub Jumptosnapshot

  41. QUESTIONS?

  42. Thanks (ackstormteam) Juan Carlos Fer Joan Carles Me Joan Pau Xavi Jordi Gonzalo Toni Victor

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