计算机病毒中英文对照外文翻译文献

中英文翻译

COMPUTER VIRUSES

What are computer viruses?

According to Fred Cohen?s well-known definition, a computer virus is a computer program that can infect other computer programs by modifying them in such a way as to include a (possibly evolved) copy of itself. Note that a program does not have to perform outright damage (such as deleting or corrupting files) in order to be called a “virus”. However, Cohen uses the terms within his definition (e.g. “program” and “modify”) a bit differently from the wa y most anti-virus researchers use them, and classifies as viruses some things which most of us would not consider viruses.

Computer viruses are bits of code that damage or erase information, files, or software programs in your computer, much like viruses that infect humans, computer viruses can spread, and your computer can catch a virus when you download an infected file from the Internet or copy an infected file from a diskette. Once the viruses is embedded into your computer?s files, it can immediat ely start to damage or destroy information, or it can wait for a particular date or event to trigger its activity. What are the main types of viruses?

Generally, there are two main classes of viruses. The first class consists of the file Infectors which attach themselves to ordinary program files. These usually infect arbitrary .COM and/or .EXE programs, though some can infect any program for which execution is requested, such as .SYS,.OVL,.PRG,&.MNU files.

File infectors can be either direct action or resident. A direct-action virus selects one or more other programs to infect each other time the program which contains it is executed ,and thereafter infects other programs when “they” are executed (as in the case of the Jerusalem) or when certain other conditions are fulfilled. The Vienna is an example of a direct-action virus. Most other viruses are resident.

The second class is system or boot-record infectors: those viruses, which infect executable code, found in certain system areas on a disk that are not ordinary files. On DOS systems, there are ordinary boot-sector viruses, which infect only the DOS boot sector on diskettes. Examples include Brain, Stoned, Empire, Azusa, and Michelangelo. Such viruses are always resident viruses.

Finally, a few viruses are able to infect both (the Tequila virus is one example). There are often called “multipartite” viruses, though there has been criticism of this name; another name is “boot-and -file” virus.

File system or cluster viruses (e.g. Dir-II) are those that modify directory table entries so that the virus is loaded and executed before the desired program is. Note that the program itself is not physically altered; only the directory entry is. Some consider these infectors to be a third category of viruses, while others consider them to be a sub-category of the file infectors.

What are macro viruses?

Many applications provide the functionality to create macros. A macro is a series of commands to perform some application-specific task. Macros are designed to make life easier, for example, to perform some everyday tasks like text-formatting or spreadsheet calculations.

Macros can be saved as a series of keystrokes (the application record what keys you press); or they can be written in special macro languages (usually based on real programming languages like C and BASIC). Modern applications combine both approaches; and their advanced macro languages are as complex as general purpose programming languages. When the macro language allows files to be modified, it becomes possible to create macros that copy themselves from one file to another. Such self-replicating macros are called macro viruses.

Most macro viruses run under Word for Windows. Since this is a very popular word processor, it provides an effective means for viruses to spread. Most macro viruses are written using the macro language WordBasic. WordBasic is based on the good old BASIC programming language. However, it has many (hundreds of) extensions (for example, to deal with documents: edit, replace string, obtain the name of the current document, open new window, move cursor, etc.).

What is a Trojan horse program?

A type of program that is often confused with viruses is a …Trojan horse? program. This is not a virus, but simply a program (often harmful) that pretends to be something else.

For example, you might download what you think is a new game; but when you run it, it deletes files on your hard drive. Or the third time you start the game, the program E-mail your saved passwords to another person.

Note: simpl y download a file to your computer won?t activate a virus or Trojan horse; you have to execute the code in the file to trigger it. This could mean running a program file, or opening a Word/Excel document in a program (such as Word or Excel) that can execute any macros in the document.

What kind of files can spread viruses?

Viruses have the potential to infect any type of executable code, not just the files that are commonly called “program files”. For example, some viruses infect executable code in the boot sector of floppy disk or in system areas of hard drives. Another type of virus, known as a “macro” virus, can infect word processing and spreadsheet documents that use macros. And it?s possible for HTML documents containing JavaScript or other types of executable code to spread viruses or other malicious code.

Since viruses code must be executed to have any effect, files that the computer treats as pure data are safe. This includes graphics and sound files such as .gif, .jpg, .mp3, .wav, .etc., as well as plain text in .txt files. For example, just viewing picture files won?t infect your computer with a virus. The virus code has to be in a form, such as an .exe program file or a Word .doc file which the computer will

actually try to execute.

How do viruses spread?

The methodology of virus infection was pretty straightforward when first computer viruses such as Lehigh and Jerusalem started appearing. A virus is a small piece of computer code, usually form several bytes to a few tens of bytes, that can do, well, something unexpected. Such viruses attach themselves to executable files—programs, so that the infected program, before proceeding with whatever tasks it is supposed to do, calls the virus code. One of the simplest ways to accomplish that is to append the virus code to the end of the file, and insert a command to the beginning of the program file that would jump right to the beginning of the virus code. After the virus is finished, it jumps back to the point of origination in the program. Such viruses were very popular in the late eighties. The earlier ones only knew how to attach themselves to .Com files, since structure of a .COM file is much simpler than that of an .EXE file—yet another executable file format invented for MS-DOS operating system. The first virus to be closely studied was the Lehigh virus. It attached itself to the file that was loaded by the system at boot time—https://www.360docs.net/doc/fe6542587.html,. the virus did a lot of damage to its host, so after three-four replications it was no longer usable. For that reason, the virus never managed to escape the university network.

When you execute program code that?s infected by a virus, the virus code will also run and try to infect other programs, either on the same computer or on other computers connected to it over a network. And the newly infected programs will try to infect yet more programs.

When you share a copy of an infected file with other computer users, running the file may also infect their computer; and files from those computers may spread the infection to yet more computers.

If your computer if infected with a boot sector virus, the virus tries to write copies of itself to the system areas of floppy disks and hard disks. Then the infected floppy disks may infect other computers that boot from them, and the virus copy on the hard disk will try to infect still more floppies.

Some viruses, known as …multipartite? viruses, and spread both by infecting files

and by infecting the boot areas of floppy disks.

What do viruses do to computers?

Viruses are software programs, and they can do the same things as any other program running on a computer. The accrual effect of any particular virus depends on how it was programmed by the person who wrote the virus.

Some viruses are deliberately designed to damage files or otherwise interfere with your computer?s operation, while other don?t do anything but try to spread themselves around. But even the ones that just spread themselves are harmful, since they damage files and may cause other problems in the process of spreading.

Note that viruses can?t do any damage to hardware: they won?t melt down your CPU, burn out your hard drive, cause your monitor to explode, etc. warnings about viruses that will physically destroy your computer are usually hoaxes, not legitimate virus warnings.

Modern viruses can exist on any system form MS DOS and Window 3.1 to MacOS, UNIX, OS/2, Windows NT. Some are harmless, though hard to catch. They can play a jingle on Christmas or reboot your computer occasionally. Other are more dangerous. They can delete or corrupt your files, format hard drives, or do something of that sort. There are some deadly ones that can spread over networks with or without a host, transmit sensitive information over the network to a third party, or even mess with financial data on-line.

What?s the story on viruses and E-mail?

You can?t get a virus just by reading a plain-text E-mail message or Usenet post. What you have to watch out for are encoded message containing embedded executable code (i.e., JavaScript in HTML message) or message that include an executable file attachment (i.e., an encoded program file or a Word document containing macros).

In order to activate a virus or Trojan horse program, you computer has to execute some type of code .This could be a program attached to an E-mail, a Word document you downloaded from the Internet, or something received on a floppy disk. There?s no special hazard in files attached to Usenet posts or E-mail messages: they?re no more

dangerous than any other file.

What can I do to reduce the chance of getting viruses from E-mail？

Treat any file attachments that might contain executable code as carefully as you would any other new files: save the attachment to disk and then check it with an up-to-date virus scanner before opening the file.

If you E-mail or news software has the ability to automatically execute JavaScript, Word macros, or other executable code contained in or attached to a message, I strongly recommend that you disable this feature.

My personal feeling is that if an executable file shows up unexpectedly attached to an E-mail, you should delete it unless you can positively verify what it is, Who it came from, and why it was sent to you.

The recent outbreak of the Melissa virus was a vivid demonstration of the need to be extremely careful when you receive E-mail with attached files or documents. Just because an E-mail appears to come from someone you trust, this does NOT mean the file is safe or that the supposed sender had anything to do with it.

Some General Tips on Avoiding Virus Infections

1.Install anti-virus software from a well-known, reputable company. UPDATE

it regularly, and USE it regularly.

New viruses come out every single day; an a-v program that hasn?t been

updated for several months will not provide much protection against current

viruses.

2.In addition to scanning for viruses on a regular basis, install an …on access?

scanner (included in most good a-v software packages) and configure it to

start automatically each time you boot your system. This will protect your

system by checking for viruses each time your computer accesses an

executable file.

3.Virus scans any new programs or other files that may contain executable

code before you run or open them, no matter where they come from. There

have been cases of commercially distributed floppy disks and CD-ROMs

spreading virus infections.

4.Anti-virus programs aren?t very good at detecting Trojan horse programs, so

be extremely careful about opening binary files and Word/Excel documents

from unknown or …dubious? sources. This includes posts in binary

newsgroups, downloads from web/ftp sites that aren?t well-known or don?t

have a good reputation, and executable files unexpectedly received as

attachments to E-mail.

5.Be extremely careful about accepting programs or other flies during on-line

chat sessions: this seems to be one of the more common means that people

wind up with virus or Trojan horse problems. And if any other family

members (especially younger ones) use the computer, make sure they know

not to accept any files while using chat.

6.Do regular backups. Some viruses and Trojan horse programs will erase or

corrupt files on your hard drive and a recent backup may be the only way to

recover your data.

Ideally, you should back up your entire system on a regular basis. If this i sn?t practical, at least backup files you can?t afford to lose or that would be difficult to replace: documents, bookmark files, address books, important E-mail, etc.

Dealing with Virus Infections

First, keep in mind “Nick?s First Law of Computer Virus Complaints”:

“Just because your computer is acting strangely or one of your programs doesn?t work right, this does not mean that your computer has a virus.”

1.If you haven?t used a good, up-to-date anti-virus program on your computer,

do that first. Many problems blamed on viruses are actually caused by

software configuration errors or other problems that have nothing to do with

a virus.

2.If you do get infected by a virus, follow the direction in your anti-virus

program for cleaning it. If you have backup copies of the infected files, use

those to restore the files. Check the files you restore to make sure your

backups weren?t infected.

3.for assistance, check the web site and support service for your anti-virus

software.

Note: in general, drastic measures such as formatting your hard drive or using FDISK should be avoided. They are frequently useless at cleaning a virus infection, and may do more harm than good unless you? re very knowledgeable about the effects of the particular virus you?re dealing with.

计算机病毒

什么是计算机病毒？

按照Fred Cohen的广为流传的定义，计算机病毒是一种侵入其他计算机程序中的计算机程序，他通过修改其他的程序从而将（也可能是自身的变形）的复制品嵌入其中。注意一个程序之所以成为“病毒”，并非一定要起彻底的破坏作用（如删除或毁坏文件）。然而，Cohen在他的定义（即“程序”和“修改”）中使用的“病毒”这个术语与大多数反病毒研究人员使用的“病毒”术语有些差别，他把一些我们多数人认为不是病毒的东西也归类为病毒。

计算机病毒是一些能破坏或删除计算机中的信息、文件或程序的代码。正如感染人体的病毒一样，计算机病毒能够扩散。当你的计算机从互联网上下载一个被感染的文件，或者从磁盘上复制一个被感染的文件时，你的计算机就会染上病毒。而一旦病毒进入到你的计算机文件中，它就能马上破坏或摧毁其中的信息，或者等到某个特殊的日期或事件来临时才触发其破坏活动。

个人计算机病毒主要有哪些类型？

一般来说，主要存在着两类计算机病毒。第一类由文件感染型病毒组成，他们将自身依附在普通的程序文件上。这些病毒通常感染任意的.COM和/或EXE文件，尽管有些也感染具有执行功能的文件，如.SYS，.OVL，.PRG和.MNU文件.

文件感染型病毒又可分为“立即执行型”和“驻留型”。立即执行型病毒在含有它的程序每次执行是都对其他的一个或多个文件进行感染，而驻留型病毒在被感染的程序第一次执行时先将自己隐藏在内存中的某个地方，以后当其他程序执行或当某些其他程序特定条件满足时就对它们进行感染（就像耶路撒冷病毒一样）。维也纳病毒是立即执行型病毒的一个例子，大多数其他病毒则是驻留型病毒。

第二类病毒是系统病毒或引导区记录感染型病毒，这些感染可执行代码的病毒出现在磁盘的某些系统区中，而不是普通文件中。在DOS系统中，常见的引导扇区病毒和主引导记录病毒，前者只感染DOS引导扇区，后者感染硬盘的主引导记录和软盘的DOS引导扇区。第二类病毒的例子包括大脑病毒、大麻病毒、帝国病毒、Azusa以及米开郎基罗病毒等，此类病毒通常为驻留型病毒。

另外，有些病毒能感染上述两种对象（如蒸馏酒病毒就是一个例子），这些

病毒常称为“多成分”病毒（尽管这个名字曾遭到过批评），它们的另一个名字是“引导区和文件型”病毒。

文件系统型病毒或“簇”病毒（如Dir-II病毒）是那种修改文件目录表项并且在文件装入、执行前就被装入和执行的病毒。注意，程序本身实际上并没有被修改，只是目录项被修改。有些人把这种感染型病毒看作是第三类病毒，而另一些人把它看作是文件感染型病毒的子类。

什么是宏病毒？

许多应用程序都提供了创建宏的功能。宏是一个完成特定应用任务的命令序列。设计宏的目的是使诸如文本格式化或电子表格计算这样的日常工作更为简单。

宏可以保存成一系列击键（即应用程序记录你按了哪些键），或者它们能够用某些特殊的宏语言像通用程序设计语言一样复杂。当宏语言允许文件被修改时，就有可能建立能将自身从一个文件复制到另一个文件上的宏。这种具有自复制功能的宏称作宏病毒。

大多数的宏病毒都是在Windows的Word软件中运行的，因为Word是一种流行的字处理器，它为病毒的扩散提供了有效的途径。大部分的宏病毒是用WordBasic宏语言编写的。WordBasic基于以前的性能良好的BASIC编程语言，然而它有很多（几百种）扩展功能（如下列文件处理功能：编辑、替换字符串、获取当前文档的名字、打开一个新的窗口、移动光标等）。

什么是特洛伊木马程序?

通常与病毒想混淆的一种程序是特洛伊木马程序.。它不是病毒，仅仅是扮作其他东西的程序（常常是有害的）。

例如，你可能下载了你认为是新游戏的东西，但当你运行它时，它删除了你硬盘上的文件。或者当你第三次运行该游戏时，该程序把你保存了的密码发送给其他人。

注意：仅仅把一个文件下载到你计算机不会激活病毒或特洛伊木马程序。你必须执行文件中的代码才能出触发它。这意味着运行一个程序文件或打开一个可以执行文档中的宏的程序（如Word或Excel）中的Word/Excel文档。

哪些文件可以传播计算机病毒？

计算机病毒有感染任何可执行代码的潜力，不仅仅是通常叫做“程序文件”