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Proof-Of-Concept: Signature Based Malware Detection for Websites and Domain Administrators

Proof-Of-Concept: Signature Based Malware Detection for Websites and Domain Administrators. - Anant Kochhar. Malware /`mæl.weə(ɹ)/ Software developed for the purpose of causing harm to a computer system and its users. Back Door, Key Logger, Botnet Zombie. Know them, “Trust” them.

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Proof-Of-Concept: Signature Based Malware Detection for Websites and Domain Administrators

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  1. Proof-Of-Concept: Signature Based Malware Detection for Websites and Domain Administrators - Anant Kochhar

  2. Malware /`mæl.weə(ɹ)/ Software developed for the purpose of causing harm to a computer system and its users. Back Door, Key Logger, Botnet Zombie

  3. Know them, “Trust” them

  4. Drive-By Downloads AKAIFRAME and Script Injections

  5. First Wave: Mass SQL Injection • First noticed in late 2007. • Tool based. • Identified vulnerable pages across the internet using search engines. • Sprayed them with SQL injection payloads- • Inserted script injections indiscriminately in all database columns • Infected data was reflected in dynamic pages

  6. Payload Source: http://www.f-secure.com/weblog/archives/00001427.html

  7. Affected Page With Rubbish Data

  8. Source: http://www.scmagazineus.com/mass-sql-injection-attack-compromises-70000-websites/article/100497/ Source: http://www.scmagazineus.com/sql-attack-hits-125000-sites/article/159445/

  9. Bulk of the spread: Self Propagation • Inserts IFrame/ Script injections in all web pages in the victim’s machine • If victim = website admin, all his websites will be updated with infected pages. • Or steals FTP passwords from victims’ computer and updates the pages directly on the web server.

  10. PC Based Security for Malwares Source: http://www.cyveillance.com/web/docs/WP_CyberIntel_H1_2009.pdf

  11. Prevention… • “Process”. • Use linux-based dedicated machines for website administration. But even the best process cannot be 100% effective because…

  12. Indirect Risks:The Legitimate can also becomes Dangerous A B Site B Iframe Injection All internal and external users of the “clean” site A are also at risk now.

  13. Accept the risk… the Alternative: Fast Detection and Quick Remedy • Contain the spread of infection. • Protect reputation of the website.

  14. Detection Part 1: Detect ALL External Sites Linking from your websites

  15. Internal Scans- Scanners that reside in the web server and scan all web pages for external links. External Scans- Crawlers, not residing in the web server, that will scan all pages from the internet. 2 Methods

  16. Internal Scans • Pros • Will be exhaustive and will scan pages behind authentication. • Cons • Will affect web server performance and can even crash the server.

  17. External Scans • Pros • Can be run as often as possible. • Has virtually no affect on the web server. • Cons • Will depend on network conditions. • Breadth and the Depth of the scan may not be exhaustive.

  18. The Scanner Must: • Detect and list all external sites in a website. • Ideally NOT visit any external websites • Because it may put the system at risk.

  19. Detection Part 2: Detecting malware spreading sites in the list of external sites.

  20. Behavior Analysis Detection Model • Visit the external site • Download suspected malware • Analyze it • And determine if it is malware or not.

  21. efg.xyz Iframe redirection Malware fashion. abc.xyz Dynamic Scan Legitimate

  22. Behavior Analysis • Expensive- requires a dedicated setup. • Slow- takes time to analyze all codes downloaded from external websites. • Newer malwares are designed to fool it- delayed activation etc. • Will not detect infected ‘site B’

  23. Signature Based Detection Model • Downloads signatures of malware infected sites. • Compares the list of external sites to the signatures.

  24. Multi Sourced Signatures Positive Matches List of external sites.

  25. Signature Based • Cheap- can be done on any machine. • Several “freely” available sources of signatures. • Fast- comparison takes a fraction of the time. • Safe- malware is not downloaded on the machine. • Will detect infected ‘site B’.

  26. Final Model • External Scanner/ crawler that will continuously scan the entire domain for external sites. • At least 2 sources of signatures. Update as frequently as possible.

  27. Ideally… • Crawl time > Signature update time. • On every signature update, the list of external site from (n-1)th crawl should be used for full comparison.

  28. On A Positive Match • Immediately remove the malware site link from the infected page. • Run AV and malware detection scans on the affected server. • Or quarantine suspected computers… • Change FTP password.

  29. Multi Sourced Signatures Positive Matches Continuous Crawl List of external sites. Compare

  30. Thank you anant.kochhar@secureyes.net

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