Melissa and LoveLetter made use of the trust that exists between friends orcolleagues．Imagine receiving an (71) from a friend who asks you to open it．This is whathappens with Melissa and several other similar email (72) ．Upon running，such wormsusually proceed to send themselves out to email addresses from the victim’s address book，previous emails，web pages (73) ． A．cracker B．user C．customer D．client

As administrators seek to block dangerous email attachments through the recognition ofwell—known (74) ，virus writers use other extensions to circumvent such protection．Executable(.exe)files are renamed to．bat and．cmd plus a whole list of other extensions and wilt still runand successfully infect target users．
B. Frequently，hackers try to penetrate networks by sending an attachment that
C. looks like a flash movie，which，while displaying some cute animation，simultaneouslyruns commands in the background to steal your passwords and give the (75) access to yournetwork．
D. 供选择答案：