计算机病毒

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文章出处：Sybil P. Parker, Computer Science Source. McGraw-Hill, Inc., 2004

计算机病毒

计算机病毒是能改变或破坏存在计算机中的数据的程序，而且它能在操作过程中不断自我复制，从而造成损害。
1987年，计算机病毒在美国四处蔓延，而且第一种计算机病毒“小球”在当年年底传播到我国。从那以后，已经发现进口和国内的病毒。迄今为止，计算机病毒已经增加到20,000多种；其中90％以上能攻击微型计算机。
计算机病毒的特征
（1）基本特征
(a)传染：计算机病毒作为一个程序，能自我复制到其他正常程序或者系统的某些部件上，例如磁盘的引导部分。这是病毒程序的基本特征。随着网络日益广泛发展，计算机病毒能够在短时间内通过网络广泛传播。
(b)潜伏：隐藏在受感染系统内的病毒并不立即发作；相反，在它发作前，需要一定时间或具备某些条件。在潜伏期内，它并不表现出任何扰乱行动，因此很难发现病毒并且病毒能够继续传播。一旦病毒发作，它能造成严重破坏。
(c)可触发性：一旦具备某些条件，病毒便开始攻击。这一特征称作可触发性。利用这一特征，我们能控制其传染范围和攻击频率。触发病毒的条件可能是预设的日期、时间、文件种类或计算机启动次数等。

Computer Virus

Computer virus is a procedure that can change or damage data stored in computers, and it can constantly duplicate itself during its operation and thus cause damage.
Computer virus widely spread in the United States in 1987, and the first computer virus "Small Ball" spread to our country by the end of that year. Since then, imported and domestic virus has been discovered. By now, computer virus has multiplied to more than 20, 000varieties; over 90% of them can attack microcomputers.
1. Features of Computer Virus
(1) Basic features
(a) Infection. Computer virus as a procedure can duplicate itself to other normal procedures or on some components of the system, for example, leading portion of disk. This is the basic feature of virus procedure. As computer network develops increasingly and extensively, computer virus can spread extensively through Internet within short time.