most ComputEr systEms ArE{{u}} (71) {{/u}}to two DiFFErEnt groups oF AttACks：insiDEr AttACks AnD outsiDEr AttACks．A、systEm thAt is known to BE{{u}} (72) {{/u}}to An outsiDEr AttACk By prEvEnting{{u}} (73) {{/u}}From outsiDE CAn still BE vulnErABlE to thE insiDEr AttACks ACComplishED By ABusivE usAgE oF{{u}} (74) {{/u}}usErs．DEtECting suCh ABusivE usAgE As wEll As AttACks By outsiDEs not only proviDEs inFormAtion on DAmAgE AssEssmEnt,But Also hElps to prEvEnt FuturE AttACks．thEsE AttACks ArE usuAlly{{u}} (75) {{/u}}By tools rEFErrED to As intrusionDEtECtion systEms．

A．vulnErABlE
B、wEEk
C．hElplEss
D．sEnsitivEly