Anirudh Ramachandran and Nick Feamster, Georgia Institute
of Technology

We study the network-level behavior of spammers, including: IP address
ranges that send the most spam, common spamming modes (e.g., BGP route
hijacking, bots), how persistent (in time) each spamming host is, botnet
spamming characteristics, and techniques for harvesting email addresses.
This presentation studies these questions by analyzing an 18-month trace
of over 10 million spam messages collected at one Internet "spam
sinkhole," and by correlating these messages with the results of IP-based
blacklist lookups, passive TCP fingerprinting information, routing
information, and botnet "command and control" traces.
We find that a small, yet non-negligible, amount of spam is received from
IP addresses that correspond to short-lived BGP routes, typically for
hijacked addresses. Most spam was received from a few regions of IP
address space. Spammers appear to make use of transient "bots" that send
only a few pieces of email over the course of a few minutes at most. These
patterns suggest that developing algorithms to identify botnet membership,
filtering email messages based on network-level properties (which are less
variable than an email's contents), and improving the security of the
Internet routing infrastructure may be prove extremely effective for
combating spam.
Link to the presentation
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