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Disabling Worms With Honeypots and Active Immunization Excerpts from "A Virtual
Honeypot Framework", Niels Provos, 13th USENIX Security Symposium, San
Diego, CA, August 2004.
Honeypots are ideally suited to intercept traffic from
adversaries that randomly scan the network. This is especially true
for Internet worms that use some form of random scanning for new
targets, e.g. Blaster or Nimda.
We fight Internet worms using the Honeyd framework and actively
counter worm propagation by immunizing infected hosts that contact
our virtual honeypots. Analogous to Moore et al., we can model the
effect of immunization on worm propagation by using the classic SIR
epidemic model. The model states that the number of newly infected
hosts increases linearly with the product of infected hosts,
fraction of susceptible hosts and contact rate. The immunization is
represented by a decrease in new infections that is linear in the
number of infected hosts.
The figure on the right shows a simulated example that tracks the
change in the susceptible, infected and immunized populations.
Our findings are going to be made available as research paper in
the near future. For questions, please contact Niels Provos.
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For example, if we assume 360,000 susceptible machines in a
32-bit address space, set the initial worm seed to 150 infected
machines and each worm launches 50 probes per second. The simulation
measures the effectiveness of using active immunization by virtual
honeypots. The honeypots start working after a time delay. The time
delay represents the time that is required to detect the worm and
install the immunization code. We expect that immunization code can
be prepared before a vulnerability is actively exploited. The two
figure on the right show the worm propagation resulting from a
varying number of instrumented honeypots. The top graph shows the
results if the honeypots are brought online an hour after the worm
started spreading. The bottom graph shows the results if the
honeypots can be activated within 20 minutes. If we wait for an
hour, all vulnerable machines on the Internet will be infected. Our
chances are better if we start the honeypots after 20 minutes. In
that case, a deployment of about 262,000 honeypots is capable of
stopping the worm from spreading.
Alternatively, it would be possible to scan the Internet for
vulnerable systems and remotely patch them. For ethical reasons,
this is probably unfeasible. However, if we can reliably detect an
infected machine with our virtual honeypot framework, then active
immunization might be an appropriate response. For the Blaster worm,
this idea has been realized by Oudot.
References
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SupportIf you have suggestions on this research or would like to
make resources available, please let me know. |
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