1 Botnets A Multifaceted Approach to Understanding the Botnet Phenomenon (Rajab/Zarfoss/Monrose/Terzis) Ryan Hannan Rohit Bhat Alan Mui Irfan Siddiqui

2 Statistical Significance What did they examine? –800,000 DNS domains examined –85,000 servers botnet-infected (11%) –65 IRC server domain names Is above data statistically significant? –Over 97,000,000 domain names exist –73,500,000.com domains (1% probed)

3 Statistical Significance Ignored non-IRC based bots –40% of bot traffic has been completely ignored –Only reviewed C&C (command and control) channels – , web, P2P, other methods were not examined

4 What was the focus of the testing? Type I bots (17% of total analysis) – Type I bots are “worm-like botnets that continuously scan…” Type-II bots (83% of total analysis) – Type II bots are: “botnets with variable scanning behavior” and “only scan after receiving a command…”

5 What was the focus of the testing? Type-I bots (17% of total analysis) – Type I bots are “worm-like botnets that continuously scan…” Type-II bots (83% of total analysis) – Type II bots are: “botnets with variable scanning behavior” and “only scan after receiving a command…” Since most of the analysis was conducted on Type-II bots, how much traffic was missed while waiting for commands to be initiated?

6 Study Duration Study lasted 3 months –Is this enough time to get an accurate set of sample data? –Do we know this 3-month stretch was indicative of “normal” traffic? –Do we know if anything happened during this 3- month period that could account for exceptionally high or low amounts of traffic?

7 Tracking Inaccuracies? Consistent inconsistency? Traffic changes frequently! *Data from

8 Tracking Inaccuracies? What if the tracking was done April – June? How about Nov. – Jan.? Skewed Results? *Data from

9 How do they know what they saw? Don’t want to be found –Botmasters intentionally use stealth techniques to remain anonymous –Bots, like all technologies, are constantly changing and evolving with time…new evolutions could already exist that they were unaware of –Encryption is being used instead of passing commands as clear-text