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Exploiting the Testing System

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International Antivirus Testing Conference. Viorel Canja, Head of BitDefender Labs, Bitdefender.

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Exploiting the Testing System

  1. 1. Exploiting the testing system Viorel Canja,Head of BitDefender Labs
  2. 2. Contents <ul><li>What does the title mean ? </li></ul><ul><li>Testing detection on wildcore </li></ul><ul><li>Testing detection on zoo collections </li></ul><ul><li>Retrospective detection tests </li></ul><ul><li>Examples </li></ul><ul><li>Feedback from the industry </li></ul><ul><li>Q&A </li></ul>
  3. 3. What does the title mean ? <ul><li>Purpose of tests: </li></ul><ul><li>to define metrics and measure the performance of AV products </li></ul><ul><li>to find am approximation for the real world performance of AV products </li></ul><ul><li>to give feedback to AV researchers about their products </li></ul><ul><li>to allow the users to make an informed decision </li></ul>
  4. 4. What does the title mean ? <ul><li>“ Define:exploit” </li></ul><ul><li>use or manipulate to one's advantage </li></ul><ul><li>draw from; make good use of </li></ul><ul><li>overwork: work excessively hard </li></ul>
  5. 5. What does the title mean ? <ul><li>To use the limitations of the testing procedure to one’s advantage. </li></ul><ul><li>The focus is on those actions which have questionable benefits for the user. </li></ul>
  6. 6. Types of tests <ul><li>detection tests on wildcore </li></ul><ul><li>detection tests on zoo collections </li></ul><ul><li>retrospective detection tests </li></ul>
  7. 7. Testing detection on wildcore <ul><li>What is wildcore ? </li></ul><ul><li>“ WildCore is a set of replicated virus samples that represents the real threat to computer users.” </li></ul><ul><li>“ When a virus is reported to us by two or more Reporters, it's a pretty good indication that the virus is out there, spreading, causing real problems to users. We consider such a virus to be 'In the Wild'.” </li></ul>
  8. 8. Testing detection on wildcore <ul><li>The Wildcore samples are known to all AV companies as soon as wildcore is published. </li></ul><ul><li>Tests are likely to be performed on exactly the same samples. This is always the case with samples of malware which does not replicate. </li></ul>
  9. 9. Testing detection on wildcore <ul><li>Quick hack: just sign all the samples with dumb ( aka automatic ) signatures. </li></ul><ul><li>Disable heuristics to avoid false positives ( if the testbed is already known there is no need for technology that detects previously unknown threats ) </li></ul>
  10. 10. Testing detection on zoo collections <ul><li>Zoo should contain a large number of files so that the statistics are as accurate as possible </li></ul><ul><li>Threats should be replicated ( where applicable ) or large numbers of samples should be used for polymorphic malware or malware that is re-generated on the server </li></ul><ul><li>The zoo should not contain garbage </li></ul>
  11. 11. Testing detection on zoo collections <ul><li>Hacks: </li></ul><ul><li>use customized settings for the test. Heuristics should be set to paranoid mode. Automatically sign all previously missed samples and white-list all previously reported false positives. </li></ul><ul><li>automatically sign all samples detected by at least one AV product just to be on the “safe” side </li></ul>
  12. 12. Testing detection on zoo collections <ul><li>Hacks (2): </li></ul><ul><li>- add detection routines for garbage that is usually found in collections. This includes detecting known false positives of other products, detecting damaged executables, detecting files produced by different analysis tools. </li></ul>
  13. 13. Retrospective detection tests <ul><li>Signature databases are frozen at a certain moment </li></ul><ul><li>Detection is tested against samples received after that moment </li></ul><ul><li>Testing should be done with default settings because most of the products are marketed as “install and forget” and the majority of users will not change the settings </li></ul>
  14. 14. Retrospective detection tests <ul><li>Has the disadvantage that it will not take into account proactive detections introduced by generic routines created for malware families that appear after the signatures are frozen </li></ul><ul><li>These routines ( or signatures ) will detect proactively subsequent variants of the same family </li></ul><ul><li>Favors aggressive heuristics if not correlated with false positive tests </li></ul>
  15. 15. Examples <ul><li>Automatic signing: </li></ul><ul><li>Av01 (1 st pair) : TR/Zapchast.CP </li></ul><ul><li>Av02 : Collected.Z </li></ul><ul><li>Av03: W32/KillAV.3B84!tr </li></ul><ul><li>Av04: Trojan.Downloader.Asks </li></ul><ul><li>Av05: Program:Win32/SpySheriff (threat-c) </li></ul><ul><li>Av06: Trojan.Gen </li></ul><ul><li>Av07 : Win32:Trojan-gen. {Other} </li></ul><ul><li>Av08: Win32/Dewnuttin.B </li></ul><ul><li>Av09: W32/Tofger.CD </li></ul><ul><li>Av10: Application/KillApp.A </li></ul><ul><li>Av11: (2 nd pair) TROJ_PROCKILL.DJ </li></ul><ul><li>Av12: Trojan.Xtssksastsm </li></ul><ul><li>Av13: (1 st pair) Trojan.Win32.Zapchast.cp </li></ul><ul><li>Av14: (2 nd pair) application ProcKill-DJ </li></ul><ul><li>Av15: Win32/ProcKill.1hj!Trojan </li></ul><ul><li>Av16: Trojan.Zapchast.CT </li></ul>
  16. 16. Examples <ul><li>Detecting other products’ false positives: </li></ul><ul><li>Av01: Backdoor.X </li></ul><ul><li>Av02: FalseAlarm.Av01.Backdoor.X </li></ul>
  17. 17. Feedback from the industry <ul><li>Automatic sample processing … </li></ul><ul><li>is a must given the number of samples received </li></ul>
  18. 18. Feedback from the industry <ul><li>… and adding detection based on the output of other AVs </li></ul><ul><li>illegal, immoral, plain wrong </li></ul><ul><li>bad idea </li></ul><ul><li>it’s common practice </li></ul><ul><li>it probably started as an attempt to have common names </li></ul><ul><li>there is no other way </li></ul>
  19. 19. Feedback from the industry <ul><li>Reporting packed files </li></ul><ul><li>if they are not malicious we should not detect them </li></ul><ul><li>some of the packers should be blacklisted while others are too widely used so must be allowed </li></ul><ul><li>an unfortunate necessity </li></ul><ul><li>professional companies do not need to use dodgy packers </li></ul>
  20. 20. Feedback from the industry <ul><li>White-listing clean apps instead of black-listing malware </li></ul><ul><li>it’s not possible </li></ul><ul><li>does not scale </li></ul><ul><li>it’s ok in controlled environments </li></ul><ul><li>better and better idea as time passes </li></ul>
  21. 21. The end … <ul><li>Q&A </li></ul>

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