Stressing and stretching
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Stressing and Stretching. John A Clark with acknowledgements to Peter Laurens, Simon Poulding, Chetan Padia, Rob Alexander and Mark Harman. Smarter Stress. Server. The Usual Denial of Service Attack. Smarter DoS: Low Rate Attack. Server.

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Stressing and Stretching

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Stressing and stretching

Stressing and Stretching

John A Clark

with acknowledgements to Peter Laurens, Simon Poulding, Chetan Padia, Rob Alexander and Mark Harman


Smarter stress

Smarter Stress

Server

The Usual Denial of Service Attack


Smarter dos low rate attack

Smarter DoS: Low Rate Attack

Server

Need only fill up buffer and then feed the server as it dispatches


Smarter dos low rate attack1

Smarter DoS: Low Rate Attack

Server

Need only fill up buffer and then feed the server as it dispatches


Stressing and stretching

Goal

  • Example basically shows that you can cause a lot of stress with little effort.

  • Usually just want to find test data inputs to stress system.

  • Question: can we devise a smart stressing language in which we can evolve interaction strategies.

    • Can the low rate DoS attack be discovered?

  • Have some preliminary results for stressing a system based on notion of music: notes/bars emphasis etc.


Other input strategy

Other Input Strategy

  • Perhaps one of the simplest “strategies” for choice of successive inputs is to specify a distribution.

    • For Boolean inputs – perhaps biased coin tossing

  • But more subtle input vectors can be created if we get rid of the usual independence assumption and embrace correlation of inputs.

  • Can evolve distributions to target specified achievement goals.

    • Motivated initially by Thevenod-Fosse et al work on “statistical testing”

      • Maximise the probability of the least covered element being covered.

      • Biut could test with an “inverted coverage criterion” – so that risky but little used or difficult to reach parts of the system state can be covered more.

  • In short, possibilities of evolving an input distribution for achieving some specified effect.


Warping systems 1

Warping Systems 1

  • Is it possible to throw die and get forty sixes in a row?

  • 666666666……66666666

  • But the chances of doing this experimentally are very small.

  • But if we allow the probabilities of each results to vary then a witness becomes more likely

    • p1=p2=p3=p4=p5=0.001 and p6=0.995

    • So why not evolve the probabilities (the system) to give the best chances of answering the question you want.

  • Possibility (hazard identification) and reliability/likelihood are different things.


Warping systems ii a

Warping Systems II-a

Want test datum for hard to reach part if the system


Warping systems ii b

Warping Systems II-b

Find test datum for stretched system


Warping systems ii c

Warping Systems II-c

Now collapse back to original system and “drag” the test data back with you.


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