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

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

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4 Know them, “Trust” them

5 Drive-By Downloads AKA IFRAME and Script Injections

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9 First Wave: Mass SQL Injection First noticed in late 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

10 Payload Source:

11 Affected Page With Rubbish Data

12 Source: compromises websites/article/100497/ Source: sites/article/159445/

13 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.

14.abc.xyz SportsFashionCollegeMovies

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16 PC Based Security for Malwares Source:

17.abc.xyz SportsFashionCollegeMovies

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

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

22 Accept the risk… the Alternative: Fast Detection and Quick Remedy 1.Contain the spread of infection. 2.Protect reputation of the website.

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

24 2 Methods 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.

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

26 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.

27 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.

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

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

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

31 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’

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

33 Multi Sourced Signatures List of external sites. Positive Matches

34 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’.

35 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.

36 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.

37 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.

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

39 Thank you