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From: Frank Knobbe (fknobbe_at_knobbeits.com)
Date: Sat Feb 08 2003 - 18:32:13 CST

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    On Sat, 2003-02-08 at 15:50, andre wrote:
    > What about blocking only a few certain attacks, that could not be easily
    > spoofed. Such like HTTP vulnerabilities and others that need a complete
    > handshake to work.

    Thank you for bringing this up. I'm a bit angered by all-or-nothing
    attitude. As you correctly said, active response doesn't need to happen
    to any and all signatures, or rule violations.

    Active response (of any kind) have their risks, but they can be
    implemented in such a fashion that the risk are bearable, and at a point
    were they are worthwhile implementing. White-lists are one approach,
    another is adding 'intelligence' so that the active response can stop by
    itself. I have tried to implement that in SnortSam by implementation of
    simple thresholds. Once a threshold (of responses) exceeds a certain
    level, SnortSam will undo the last blocks (it modifies firewalls and
    routers) and then fall silent, or passive, until the level of requests
    falls below threshold level, and then some (additional time).

    It's all a matter of checks'n'balances. Imho, programs _can_ be written
    to avoid race conditions or situation where they might get a locked in a
    loop (like responding to the response of other IDSs.... that was a nice
    example).

    The idea of implementing safety measures and self-destruct levers seems
    to fall short in the race to market with fancy software these days...

    Regards,
    Frank

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