考研考试

根据网考网考试中心的统计分析，以下试题在2016-1-19日考研习题练习中，答错率较高，为：83%
【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, of CERT, an internet-security centre at Carnegie-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”. In English, 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 wrote Blaster 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 like Blaster is to design a fairy godmother worm that goes around repairing vulnerable machines automatically. In the case of Blaster someone seems to have tried exactly that with a program called Welchi. However, according to Mr Haley, Welchi has caused almost as many problems as Blaster 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 by CSX, a freight company on America'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 as Blaster did
[B] is a program designed by Haley to detect worms like Blaster
[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

，答错率：83%
试题解析：
26. 【答案】A 【解析】这是一道细节题。根据第一段的内容，巨无霸破坏的主要手段是用大量的邮件，显然答案为A。 27. 【答案】A 【解析】这是一道词义题。根据首段末尾几句，“doctor”一词意为“伪造”，上下句语义才能连贯，而“falsify”正是这个意思，故为答案。 28. 【答案】D 【解析】这是一道细节题。本文介绍了两种病毒，文...查看试题解析出处>>