RE: Intrusion Risk Assessment

From: Robert Buckley (
Date: 01/07/03

  • Next message: Joseph M Hoffman: "RE: IDS Common Criteria"
    From: Robert Buckley <>
    To: 'Rob Shein' <>,,
    Date: Tue, 7 Jan 2003 12:32:20 -0500 

    Many people like to use this equation:

    Scale from -10 through +10
    (lethality + criticality) - (net_defense + host_defense) = attack success
    where lethality is the level of compromise the attack offers
    criticality defines the systems purpose, is it a core device or someone's
    workstation etc.
    net + host defense are self explanatory.

    Core Cisco router being attacked on the http port (There is a well known
    vulnerability here)
    (5 + 5) - ( 0 + 0 ) = 10
    The probability of a successful attack is 10.
    It was a lethal attack, on a core device, where I had no net defense, nor
    any host defense.
    Let change the view...

    (5 + 5) - (5 + 5) = 0
    The probability of a successful attack is 0.
    It was a lethal attack, on a core device, but I have acl's denying port 80
    to this device, and
    the host doesn't run http services at all.

    One more example:
    netbios name mangling attack against a workstation
    (2 + 1) - (0 + 5) = -2
    lethality is a denial of service, criticality is low because its a
    I have no net defense but up to date on the patch that prevents the attack.
    The probability of success on this attack is -2

    Of course, its up to the individual to put values on the parameters, so one
    analyst may have a
    different result than the next.

    Hope this helps you.

    -----Original Message-----
    From: Rob Shein []
    Sent: Monday, January 06, 2003 7:36 PM
    Subject: RE: Intrusion Risk Assessment

    The problem with this is, define "damage." IDS systems are not aware of
    the nature of what they defend. An IIS exploit might be utterly useless
    against an apache web server, but the IDS is not intrinically aware of
    which servers are apache and which are IIS. Add to that the fact that
    such severity levels as "minor damage" or "minimal access to recover,"
    are dependent upon the information stored on a machine (which no current
    IDS could ever be cognizant of) as well as the role of that machine.

    > -----Original Message-----
    > From: []
    > Sent: Monday, January 06, 2003 12:54 PM
    > To:
    > Subject: Intrusion Risk Assessment
    > Anyone know of any IDS risk assessment matrixes out there?
    > I'm looking for something like the following:
    > Rating Severity
    > 1 No Damage a. Not possible to exploit (or)
    > b. No damage (or)
    > c. Hoax
    > 2 Harassment a. Possible damage,
    > unconfirmed (or)
    > b. Temporarily shuts down
    > services and/or temporarily prevents access to information
    > 3 Minor Damage a. Short-term impact (or)
    > b. Exploit allows access
    > to view files (or)
    > c. Minimal effort required
    > to recover
    > 4 Moderate Damage a. The exploit is easy to
    > perform (or)
    > b. Important systems can
    > be effected with administrative compromise (or)
    > c. Exploit allows full
    > access to files (or)
    > d. Long-term effects,
    > significant effort may be required to recover
    > 5 Heavy Damage a. The exploit is easy to
    > perform (and)
    > b. An exploit will cause
    > severe damage to multiple computers (and/or)
    > c. Requires reinstallation
    > or recovery from backup
    > Robert Huber
    > Bank One Information Security
    > Phone: 302-282-2234
    > Pager: 888-646-3502
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