Computer Virus
Dialogue
摘要：[对话训练]
Dialogue 1
A: Do you have virus protection software on your PC?
B:No, I'm always installing new software, and getting rid of old programs.
Virus protectionsoftware usually makes that more of a hassle.
A:But what will you do if you get a virus?
B: I guess I'll just reformat my hard drive and start over.
Dialogue 2
A: Computer prices are really coming down.
B: Not for me they're not.
A:What do you mean?
B:I mean my wife has discovered how to shop on the web!
Dialogue 3
This is a mouse,With the mouse we can move the cursor very quickly.
Look at thescreen, See the little line that blinks?
That's thecursor.
You can begin totype there.
B: But I don't want to type there.
A: Then move the cursor.
Watch, I'll holdthe mouse in my hand.
Now I'll move itacross the table.
See the cursormove?
Dialogue 4
A: I tried to copy a letter to another disk.
But I pressedthe wrong key.
I erased my mostimportant letter.
B: That's all right.
We always have abackup copy.
A:I don't know .I deleted the backup. too.
B: Well, we still have a hard copy.
It's in the filecabinet.
Professional Terms
passage
摘要：文章训练
Vocabularies
employee n.
essential a.
favorite a.
hire vt.
integrity n.
intentionallyad.
intervention n.
motive n.
pervasiveness n.
replicate vt.
subsequently ad.
subtly ad.
unaffected ad.
uninfected a.
virus a.
whatever n.
Passages
What is acomputer virus?
A computer virusis one kind of threat to the security and integrity of computer systems.
Like other threats,a computer virus can cause the loss or alteration of programs or data.
Unlike manyother threats,a computer virus can be spread from program to program and fromsystem to system without direct human intervention.
notes
He was coveredwith snow from head to foot.
He stuck to hispost from beginning to end.
The essential component of a virus is aset of instructions which
when executed,spreads itself to other ,previously unaffected, programs or files.
First , itcopies itself into previously uninfected programs or files.
Second (perhapsafter a specific number of executions, or on a specific date) it executeswhatever other instructions the virus author included in it.
Depending on themotives of the virus author, these instructions can do anything at all.
includingdisplaying a message ,erasing files or subtly altering stored data.
In some cases ,avirus may contain no intentionally harmful or disruptive instructions at all.
Instead , it maycause damage by replicating itself and taking up scarce resources, such as diskspace, CPU time ,or network connections.
Let us nowexamine a particular sequence of events by which virus could enter anorganization and spread within it .
Suppose that theorganization hires an outside person to come in and perform some work.
Part of thatperson's work involves working on one of the organization's personal computers.
The personbrings in a few programs to aid in this work, such as a favorite text editor.
Without theperson having realized it ,the text editor may be infected with a virus.
Notes
摘要：文章训练
Using thateditor on one of the organization's machines causes the virus to spread fromthe editor to one of the progarams stored on the organization's machine,perhapsto a spreadsheet program.
When an employeeuses that spreadsheet subsequently, the virus can be spread to another progarm.
perhaps to adirectory listing progam that the employee keeps on the same floppy disk as thespreadsheet data files.
The listingprogram is then infected.
and theinfection can be spread to other computers to which this floppy disk is taken.
If theemployee's computer is connected to the organization's network.
the employee maysend the listing program to another user over the network.
In either case,the virus can spread to more users, and more machines, via floppy disks ornetworks.
Each copy of thevirus can make multiple copies of itself and can infect any program to which ithas access.
As a result ,the virus may be able to spread throughout the organization in a relativelyshort time.
Each of theinfected programs in each of the infected machines can execute whatever otherinstructions the virus author intended.
If theseinstructions are harmful or disruptive ,the pervasivences of the virus maycause widespread harm
Traditionalsecurity measures have attempted to limit the number of security incidents toan acceptable level.
A singleincident of lost files in a year may be acceptable loss, for instance.
While this isimportant it only addresses partial,because single virus is able to spreadthroughout an organization.
the damage thatit could cause may be much greater than what could be caused by any individualcomputer user.
Limiting thenumber of initial vital infections of an organization is important,but it isoften not feasible to prevent them entirely.
As a result ,itis important to be able to deal with them when they occur ,and to take actionsto erase them.
