Full Disclosure mailing list archives
Re: ROSI
From: Jonathan Leffler <jleffler () us ibm com>
Date: Thu, 8 Apr 2004 10:16:25 -0700
"Curt Purdy" <purdy () tecman com> wrote:
ROSI [...] Annual Loss Expectancy (ALE) was figured. ALE is an attack's
damage
multiplied by frequency. Determining cost-benefit (R-E) + T = ALE R-ALE = ROSI R = the cost per year to recover from an intrusion E = the savings gained by stopping the intrusion T = the cost of the intrusion detection tool ALE = the Annual Loss Expectancy ROSI = Return On Security Investment
That formula appears to reduce to ROSI = E - T, though the units of the terms in the equations (dimensional analysis) make me suspicious that the formula is incomplete or the definitions of the terms are too loose (R in $/y; E in $; T in $, ALE in $/y; ROSI units unclear).
www.csds.uidaho.edu/director/costbenefit.pdf
That URL does not appear to be working this morning. -- Jonathan Leffler (jleffler () us ibm com) STSM, Informix Database Engineering, IBM Data Management 4100 Bohannon Drive, Menlo Park, CA 94025 Tel: +1 650-926-6921 Tie-Line: 630-6921 "I don't suffer from insanity; I enjoy every minute of it!" _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
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