Exposure with anti-virus
Wednesday, March 17, 2010
4:36 PM
Exposure with anti-virus
No such thing as 0 exposure. 
Race between virus creation and signature posting. 
Risk is that virus will arrive between creation time and rule posting time. 
Decompose λ into λ1 + λ2, where λ1 is arrivals between creation and posting, and λ2 is arrivals after posting. 
λ1 << λ2.
Exposure = λ1 ∆T C D << λ ∆T C D.
Value of anti-virus = λ2 ∆T C D.