每日一练：考研考研英语每日一练(2019/6/5)
【分析解答题】Text 2
SoBig.F was the more visible of the two recent waves of infection because it propagated itself by e-mail, meaning that victims noticed what was going on. SoBig.F was so effective that it caused substantial disruption even to those protected by anti-virus software. That was because so many copies of the virus spread (some 500,000 computers were infected) that many machines were overwhelmed by messages from their own anti-virus software. On top of that, one common counter-measure backfired, increasing traffic still further.Anti-virus software often bounces a warning back to the sender of an infected e-mail, saying that the e-mail in question cannot be delivered because it contains a virus. SoBig.F was able to spoof this system by “harvesting” e-mail addresses from the hard disks of infected computers. Some of these addresses were then sent infected e-mails that had been doctored to look as though they had come from other harvested addresses. The latter were thus sent warnings, even though their machines may not have been infecteD、
Kevin Haley of Symantec, a firm that makes anti-virus software, thinks that one reason SoBig.F was so much more effective than other viruses that work this way is because it was better at searching hard-drives for addresses.Brian King, ofCERT, an internet-security centre atCarnegie-Mellon University in Pittsburgh, notes that, unlike its precursors, SoBig.F was capable of “multi-threading”: it could send multiple e-mails simultaneously, allowing it to dispatch thousands in minutes.
Blaster worked by creating a “buffer overrun in the remote procedure call”. InEnglish, that means it attacked a piece of software used by Microsoft's Windows operating system to allow one computer to control another. It did so by causing that software to use too much memory.
Most worms work by exploiting weaknesses in an operating system, but whoever wroteBlaster had a particularly refined sense of humour, since the website under attack was the one from which users could obtain a program to fix the very weakness in Windows that the worm itself was exploiting.
One way to deal with a wicked worm likeBlaster is to design a fairy godmother worm that goes around repairing vulnerable machines automatically. In the case ofBlaster someone seems to have tried exactly that with a program called Welchi. However, according to Mr Haley, Welchi has caused almost as many problems asBlaster itself, by overwhelming networks with “pings”—signals that checked for the presence of other computers.
Though both of these programs fell short of the apparent objectives of their authors, they still caused damage. For instance, they forced the shutdown of a number of computer networks, including the one used by the New York Times newsroom, and the one organising trains operated byCSX, a freight company onAmerica's east coast.
Computer scientists expect that it is only a matter of time before a truly devastating virus is unleasheD、
26. SoBig.F damaged computer programs mainly by ____.
[A] sending them an overpowering number of messages
[B] harvesting the addresses stored in the computers
[C] infecting the computers with an invisible virus
[D] destroying the anti-virus software of the computers
27. Which of the following best defines the word “ doctored” (line , parA、1) ?
[A] falsified [B] cured
[C] deceived [D] diagnosed
28.Compared with SoBig.F,Blaster was a virus that was _____.
[A] more destructive
[B] more humorous
[C] less vulnerable
[D] less noticeable
29. From the text we learn that Welchi ____.
[A] is a wicked worm causing as many damages asBlaster did
[B] is a program designed by Haley to detect worms likeBlaster
[C] is a program intended to fix the infected machines
[D] is a worm meant to defeat the virus with “ pings”
30. The tone of the text can best described as _____.
[A] optimistic and humorous
[B] analytical but concerned
[C] passionate but pessimistic
[D] scholarly and cautious
在下面提交答题后即可查看答案与试题解析
发布评论 查看全部评论