Inferring Internet Denial-of-Service Activity

David Moore, Geoffrey M Voelker, Stefan Savage

Presented by Yuemin Yu – CS290F – Winter 2005

Outline

Motivation Attack types Backscatter analysis Results Conclusion

Motivation

“How to prevalent are DOS attacks today on the internet?”

Nature of the current treats Longer term analyses of trends and recurring

patterns of attacks Publish quantitative data about attacks

Attack Types

Logic attacks Exploit software vulnerabilities Software patches

Flooding attacks Distributed DoS Spoof source IP address randomly Exhaust system resources

Backscatter

Attacker uses randomly selected source IP address

Victim reply to spoofed source IP Results in unsolicited response from victim to

third party IP addresses

Backscatter

Backscatter Analysis m attack packets sent n distinct IP address

monitored Expectation of

observing an attack:

R’ Actual rate of attack: R extrapolated attack

rate

Analysis Assumptions

Address uniformity Spoof at random Uniformly distributed

Reliable delivery Attack and backscatter traffic delivered reliably

Backscatter hypothesis Unsolicited packets observed represent

backscatter

Attack classifications

Flow-based Based on target IP address and protocol Fixed time frame (Within 5mins of most recent

packet) Event-based

Based on target IP address only Fixed time frame

Data collection

/8 network 2^24 IP 1/256 of internet address space

Data collections

Collect data extract following information TCP flags ICMP payload Address uniformity Port settings DNS information Routing information

Response/Used Protocols

Rate of attack

Victims by ports

Attack Duration Cumulative - Probability

Cumulative probability density

Top level domain

Victims by Hostnames

Autonomous System

Repeated Attacks

Conclusion

Observed 12,000 attacks against more than 5,000 distinct targets.

Distributed over many different domains and ISP

Small # long attacks with large % of attack volume

An unexpected amount of attacks targeting home, foreign, specific ISP

Thanks

Questions?