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Chapter 13 Security Technologies

By Marjorie Watkins,2014-06-30 09:08
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Chapter 13 Security Technologies

Chapter 13 Security Technologies

    13.1 Computer Security

    13.1.1 . Threats to Computer Security

    Threats to computer security are computer crime (including Viruses and electronic break-ins) and natural and other hazards.

     A computer crime is an illegal action in which the perpetrator uses special knowledge of computer technology. Computer crime can take various forms, including:

    Damage——disgruntled employees sometimes attempt to destroy computers, programs, or files. In recent years, computer viruses have gained wide notoriety. Viruses are programs that migrate through networks and operating systems and attach themselves to different programs and databases.

    Theft——theft can take many formsof hardware, of software, of data, of computer time.

    Thieves steal equipment, of course, but there are also white-collar crimes. Thieves steal data in

    the form of confidential information such as preferred client lists. They also use (steal) their companys computer time to run another business.

    Manipulation——finding entry into someones computer network and leaving a pranksters

    message may seen like fun, which is why hackers do it. It is still against the law. Moreover, even if the manipulation seems harmless, it may cause a great deal of anxiety and wasted time among network users.

    There are plenty of other hazards to computer systems and data besides criminals. They include the following

    Natural Hazards——fires, floods, wind, hurricanes, tornadoes, and earthquakes. Even home computer users should store backup disks of programs and data in safe location in case of fire or storm damage.

    Civil Strife and Terrorism——wars, riots, and other forms of political unrest are real risks in some parts of the world. Even people in developed countries, however, must be mindful that acts of sabotage are possible.

    Technological Failures——hardware and software dont always do what they are supposed to

    do. For instance, too little electricity, caused by a brownout or blackout, may cause the loss of data in primary storage.

    Human Errors——human mistakes are inevitable. Data-entry errors are probably the most commonplace. Programmer errors also occur frequently. Some mistakes may result from faulty design, as when a software manufacturer makes a deletion command closely resembling anther command.

    13.1.2. Measures to Protect Computer Security

    In recent years, Internet changes our life a lot. We use E-mail and Internet phone to talk with our friends, we get up-to-date information through web and we do shopping in the cyber-market.

Internet has many advantages over traditional communication channels, e.g. It’s cost effective, it

    delivers information fast and it is not restricted by time and place. The more people use Internet, the more concerns about Internet security.

    1. Encryption techniques

    Encryption is the way to solve the data security problem. There are two kinds of encryption techniquessymmetric key encryption and asymmetric key encryption.

    For symmetric key encryption, both parties should have a consensus about a secret encryption key. When A wants to send a message to B, A uses the secret key to encrypt the message. After receiving the encrypted message, B uses the same (or derived) secret key to decrypt the message. The advantage of using symmetric key encryption lies in its fast encryption and decryption processes (when compared with asymmetric key encryption at the same security level).

    For asymmetric key encryption, there is a pair of keys for each party: a public key and a private key. The public key is freely available to the public, but only the key owner gets hold of the private key. Messages encrypted by a pubic key can only be decrypted by its corresponding private key, and vice versa. When A sends message to B, A first gets Bs public key to encrypt the

    message and sends it to A. After receiving the message, B uses his private key to decrypt the message. The advantage comes in the public key freely available to the public, hence free from any key exchange problem.

    2.Digital certificate

    Digital certificate is an identity card counterpart in the computer society. When a person wants to get a digital certificate, he generates his own key pair, gives the pubic key as well as some proof of his identification to the Certificate Authority (CA). CA will check the persons

    identification to assure the identity of the applicant. If the applicant is really the onewho claims

    to be, CA will issue a digital certificate, with the applicants name, E-mail address and the

    applicants pubic key, which is also signed digitally with the CAs private key. When A wants to

    send B a message, instead of getting Bs pubic key, A now has to get Bs digital certificate. A first

    checks the certificate authoritys signature with CAs public key to male sure its a trustworthy

    certificate. Then A obtains Bs pubic key from the certificate, and uses it to encrypt message and sends to B.

    3. Authentication

    Authentication is an important part of everyday life. The lack of strong authentication has inhibited the development commerce. It is still necessary for contracts, legal documents and official to be produced on paper. Strong authentication is then, a key requirement if the Internet is to be used for electronic commerce. Strong authentication is generally based on modern equivalents of the one time pad. For example tokens are used in place of one-time pads and are stored on smart cards or disks.

    13.2 Computer Viruses

    13.2.1. Whats a Virus?

    Computer viruses are called viruses because they share some of the traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from

    person to person. Computer viruses are just one example of what is commonly referred to as malicious code or malicious programs. Malicious programs are created to perform a series of harmful actions on a computer system. Examples of some actions include file deletion, file corruption, data theft, and the less harmful but equally annoying practical joke. These programs often remain dormant and hidden until an activation event occurs. Once an infected programs is executed or an infected operating system performs a task, the virus is activated. The virus will first determine whether it should be executed. In the event that it should not be executed, it will attempt to locate and identify other susceptible programs, disks, or systems. Any such item will then be infected. After determining that all susceptible items carry a copy of the virus, the virus will stop and allow normal operations to proceed. If the virus meets all of its internal conditions to execute, it will do so. Upon completion of execution, the virus may either reset its conditions or remove itself. The virus will complete and allow normal computation to continue. While this process may seem time consuming and obvious to the user, it is not. Computers operate so quickly nowadays that this process may go easily unnoticed, and often does.

    13.2.2. What Kinds of Virus are There

    There are four main types of viruses: shell, intrusive, operating system, and source code. Shell viruses wrap themselves around a host and do not modify the original program. Shell program are easy to write, which is why about half of all viruses are of this type. Intrusive viruses invade an existing program and actually insert a portion of themselves into the host program. Intrusive viruses are hard to write and difficult to remove without damaging the host file. Shell and intrusive viruses most commonly attack executable program file-those with COM or .EXE extension-although data are also at some risk. Operating system viruses work by replacing parts of operating system with their own logic. Very difficult to write, these viruses have the ability, once booted up, to take total control of your system. Source code viruses are intrusive programs that are inserted into a source program such as those written in Pascal prior to the program being compiled.

    13.2.3. Effects of Computer Virus

    The effects of computer virus to the society could be divided into several parts: individuals, companies, Networks/linked enterprises/universities and to the whole Society. Computer Viruses can create much fuss to an individual user, wiping off his data inside the hard disk, least effects may include deletion of programs such as games, or some files which could be easily recovered, or taking up hard drive spaces. Computer Viruses can be a great threat to a company. A company may lose important documents which may mean the lost of capital. This will trigger chain reactions such that time will also be spent, so as monkey. Companies have to bear a great cost to recover fully. Similar to the threats to companies, Network enterprises do not only cause harm to the company, but also spread viruses to different locations. As a fact, global networks are big channels for viruses to spread. Linked Universities are likely to spread viruses, causing fuss to the students, while linked banks may even cause system breakdowns which may directly threaten the operation of the banks, etc. One step further, the operation breakdown of companies causes prelims to the societys normal operation. Since time means money, a great loss of money is likely to occur. Flights be delayed, money cannot be withdrawn, servers stop operation etc.

    13.2.4How can We Prevent Virus Attacks

    New computer viruses are written all the time, and its important to understand how your

    system can be exposed to them and what can do to protect your computer. Follow the suggestions listed below to substantially decrease the danger of infecting your computer system with a potentially dangerous computer virus.

    ? Be very cautions about inserting disks from unknown sources into your computer.

    ? Always scan the disks files before operating any of them.

    ? Only download Internet files from reputable sites.

    ? Do not open e-mail attachments (especially executable files) from strangers

    ? Purchase, install, and use an anti-virus software program. The program you choose must provide three functions: Detection, Prevention, Removal.

    ? As new viruses are created everyday, upgrade your anti-virus software regularly. Anti-virus has been carefully designed to help you reduce the risk of a virus infecting your computer. Anti-virus examines your system for characteristics of specific viruses or classic viruses. When it detects something with one of these characteristics, it warns you and tries to clean (remove) the virus. No program can entirely eliminate the risk of viruses, but there are a few simple things you can do to make sure the risk is reduced.

    If you are truly worried about traditional (as opposed to e-mail) viruses, you should be running a more secure operating system like UNIX. If you are using an unsecured operating system, then buying virus protection software is a nice safeguard. If you simply avoid programs from unknown sources (like the Internet), and instead stick with commercial software purchased on CDs, you eliminate almost all of the risk from traditional viruses. In addition, you should disable floppy disk bootingmost computers now allow you to do this, and that will eliminate the risk of a boot sector virus coming in from a floppy disk accidentally left in the drive. You can

    prevent many viruses by only opening e-mail attachments when you know where the e-mail came from and what the attachment is. You should never double-click on an attachment that contains an executable file. Attachments that come in as Word files (.DOC), spreadsheets (.XLS), images (.GIF and .JPG), etc., are data files and they can do no damage. A file with an extension like EXE, COM or VBS is an executable, and the executable can do any sort of damage it wants. Once you run it, you have given it permission to do anything on your machine.

    13.3 Computer Hackers

    13.3.1. Introduction

    In computer programming, hacker is a person who is an exceptionally skilled computer programmer, and programs computers for recreation or as hobby. In computer virus, hacker is a person who “breaks into” computers without authorization, either for malicious reasons or just to

    prove it can be done. In data security, hacker is an unauthorized user who tries to gain entry to a computer network by defeating the system's access controls.

    13.3.2. Motivations behind Hacking

    The motivations behind hacking are an issue that is discussed heavily due to the importance of understanding the hacker’s psychology and the fuel that encourages him/her to perform such illegal activities, also because hackers view about what they are doing is far different from our

    views as victims. Hacking is motivated by the desire of imposing power and improving knowledge, searching for convenience rather than making money. It’s a matter of self convenience and satisfaction so that’s why motivations differ from one hacker to another but they all share the

    feel of addiction, curiosity and the need to impose their power. Motivations behind hacking are difficult to capture because it’s related to each hacker way of thinking or belief .

    13.3.3. Types of attack

    We list a number of hacking attacks that are most commonly used in breaking system and causing disruption and damage for services. These attacks can be summarized as following:

    1. Software Theft: means software will be hacked by producing illegal copies and selling them without the permission of the owner. This will result in bankruptcy and failure to companies that spend millions developing and creating software that will be sold later on with the cheapest prices in an unauthorized way.

    2. Theft of business secrets: means that trading and business information is stolen for the benefit of other companies.

    3. Theft of information: means that all types of information and data are stolen for a particular benefit or self-motivation.

    4. Denial of service: means that hacker will break into a system and disable different operations and cancel all account so that all users won’t be able to access their own information.

    5. Terrorism: known as information terrorism and occurs when dataflow is disrupted causing the system to break down and stop providing services for a period of time.

    Hacking should be halted and stopped. To know how to stop it we should know the reason behind the birth of hack, and to know why to stop it we should know the consequences and effects of hacking.

    13.3.4. Effects on Society

    Hacking effects can be categorized into three types: effects on individuals, organizations, economy and effects on countries. The most important issue to recognize is that victims are the only ones who feel the threat and effects of hacking attacks, and our duty is to inform other people about the danger of hacking to be cautious and alert which helps in preventing hacking attacks from happening event .

    13.3.5 Society response (solutions)

    The war against hacking is a continuous battle that has a starting point with no end at all. The world is using a variety of methods either to halt attacks or minimize their effects on different perspectives. The best way to minimize the effect of attacks or even avoid them is by building a well educated computer user who can gain benefit from different security techniques in the war against hacking. The first step to allocate hacking activities should be by applying information security policies, and nowadays policies are running in a large number of organizations, these policies imply that all employees should sign a workplace behavior sheet specially the ones dealing with sensitive data and information that must be kept secret. On the other hand, there is a negative opinion and blames policies and restrictions for the limitation of what we can do online.

    13.3.6 Conclusion

Hackers are responsible of the huge development in computer and Internet technology, but

    these days we consider them as thieves and intruders who penetrated our own privacy and used the

    achievements they were behind for their own benefit.

    Hackers have different opinions and motivations. However, they all share the spirit of

    challenge and always trying to prove their capabilities of doing what all believe is impossible.

    Hackers believe that information should be shared and they fight against information owning.

    New Words and Expressions

    hazard [,?,?;,] n. 危险(), 危险状态;

    prankster [,??,????;;??] n. 开玩笑者:恶作剧者 encryption [in'krip~;n] n. 加密术(密码术

    decrypt [di:'kript] v. 解密(解释明白

    certificate [?;,?????;?] n. 证书(vt. 发给证明书 counterpart [,?????;?:!?] n. 副本(配对物 fuss [fΛs] n. 忙乱(大惊小怪

    malicious [?;,??~;?] adj. 恶意的

    trigger [,???,;;??] vt. 引发(引起

    breakdown [,:????,???] n. 崩溃

    detection [,?,???~;;??] n. 发觉(侦查(检测 upgrade [??,,???,] n. 升级 vt. 使升级

    hacker [,?,?;] n. 电脑黑客:计算机窃贼, 计算机新技术挑战者 exceptionally [??,???~;?;;???] adv. 特别地:异常地 psychology [???,?(?;,??,;;(;?;???] n. 心理学 impose [??,?;??] v. 强加:强迫

    addiction [;,,??~;;??] n. 沉溺, 上瘾

    perspective [?;,???????] n. 观点, 看法

    Phrases and Expressions

    computer security 计算机安全

    illegal action 非法行为

    computer time 计算()时间

    primary storage 主存储器

    public key 公开密钥

    digital certificate 数字证书

    symmetric key encryption 对称密钥加密

    asymmetric key encryption 非对称密钥加密

    Certificate Authority 证书授权机构

    anti-virus 防病毒的(抗病毒的

    computer virus 计算机病毒

    malicious code 恶意代码

    source code 源代码

    malicious program 恶意程序

    activation event 激活事件

    anti-virus software 反病毒软件

    chain reaction 链式反应

    break into 破门而入, 侵占

    in accordance to 按照,根据

    illegal activities 不法活动 ,非法活动

    make money 赚钱

    security policy 安全政策

    computer resource 计算机资源

    computer system 计算机系统

    Exercises

    1. Fill in the blanks according to the text:

    (1) Internet has many over traditional communication channels, e.g.

    (2) There are two kinds of encryption techniquessymmetric key encryption and

    key encryption.

    (3) For key encryption, both parties should have a consensus about a secret encryption key.

    (4) For key encryption, there is a pair of keys for each party: a public key and a private key.

    (5) Digital is an identity card counterpart in the computer society. When a person wants to get a digital certificate, he generates his own key pair to the Certificate Authority (CA).

    (6) A computer passes from computer to computer like a biological virus passes from person to person.

    (7) Once an infected programs is executed or an infected operating system performs a task, the virus is .

    (8) viruses wrap themselves around a host and do not modify the original program.

    (9) If you are truly worried about traditional (as opposed to e-mail) viruses, you should be running a more secure operating system like .

    (10) has been carefully designed to help you reduce the risk of a virus infecting your computer.

    (11) In computer programming, is a person who is an exceptionally skilled

    computer programmer, and programs computers for recreation or as hobby.

    (12) behind hacking are difficult to capture because it’s related to each hacker way of thinking or belief

    (13) The most important issue to recognize is that victims are the only ones who feel the threat and effects of hacking attacks, and our duty is to inform other people about the danger of hacking to be cautious and alert which helps in hacking attacks from happening

    event .

    (14) The war against hacking is a battle that has a starting point with no end at all.

    (15) Hackers believe that information should be and they fight against

    information owning.

    2. Translate the following terms or phrases from English into Chinese and vice versa:

    (1) up-to-date (16) 加密技术

    (2) computer security (17) 非法行为

    (3) symmetric key encryption (18) 对称密钥加密

    (4) digital certificate (19) 万维网

    (5) primary storage (20) 私人密钥

    (6) operating system (21) 恶意程序

    (7) computer system (22) 激活事件

    (8) in some cases (23)计算机病毒

    (9) malicious code (24)引导区

    (10) attack phase (25)反病毒软件

    (11) computer resource (26) 非法活动

    (12) breaks into (27) 计算机系统

    (13) negative opinion (28) 因特网技术

    (14) business information (29) 数据库

    (15) make money (30) 安全政策

    3. Decide whether each of the following statements is true or false according to the text:

    (1) For asymmetric key encryption, both parties should have a consensus about a secret encryption key.

    (2) For symmetric key encryption, there is a pair of keys for each party: a public key and a private key.

    (3) Threats to computer security are computer crime (including Viruses and electronic break-ins) and natural and other hazards.

     (4) The more people use Internet, the more concerns about Internet security.

     (5) Encryption is the way to solve the data security problem.

    4. Translate the following sentences into Chinese:

    (1) We use E-mail and Internet phone to talk with our friends, we get up-to-date information through web and we do shopping in the cyber-market.

    (2) Messages encrypted by a pubic key can only be decrypted by its corresponding private key, and vice versa.

    (3) If the applicant is really the onewho claims to be, CA will issue a digital certificate,

    with the applicants name, E-mail address and the applicants pubic key, which is also signed

    digitally with the CAs private key.

    (4)It is still necessary for contracts, legal documents and official to be produced on paper. Strong authentication is then, a key requirement if the Internet is to be used for electronic commerce.

    (5) A first checks the certificate authoritys signature with CAs public key to male sure its a

    trustworthy certificate.

     5. Translate the following paragraph into Chinese:

    Digital certificate is an identity card counterpart in the computer society. When a person wants to get a digital certificate, he generates his own key pair, gives the pubic key as well as some proof of his identification to the Certificate Authority (CA). CA will check the persons

    identification to assure the identity of the applicant. If the applicant is really the onewho claims

    to be, CA will issue a digital certificate, with the applicants name, E-mail address and the

    applicants pubic key, which is also signed digitally with the CAs private key. When A wants to

    send B a message, instead of getting Bs pubic key, A now has to get Bs digital certificate. A first

    checks the certificate authoritys signature with CAs public key to male sure its a trustworthy

certificate. Then A obtains Bs pubic key from the certificate, and uses it to encrypt message and

    sends to B.

参考译文: 13 安全技术

    13.1 计算机安全

    13.1.1;计算机安全的威胁

    计算机安全的威胁有犯罪!包括病毒和电子入侵,和自然及其他灾害。

    计算机犯罪是一种非法行为(犯罪分子使用特别的计算机技术知识。计算机犯罪有多种形式(包括,

    破坏——心怀不满的员工有时企图破坏计算机、程序或文件。近年来(计算机病毒已经臭名远扬。病毒是通过网络“移植”的程序(它们操纵系统(依附于不同的程序和数据库上。

    偷窃——偷窃有多种形式—硬件、软件、数据、计算机时间(当然也偷盗设备(但是也叫“白领犯罪”。窃贼盗取机密情报如首选是客户表单(他们也使用!偷,他们公司的计算机时间去忙里一个交易。

    操纵——发现别人计算机网络的入口(留下类似玩笑的信息(是黑客的做法。这仍是违反法律的。此外(即使这种操纵看起来是无害的(它仍会在网络用户中引起焦虑和时间的两费。

    除了犯罪外(计算机系统和数据还有大量其他的危险(他们包括如下内容,

    自然灾害——火、洪水、风、飓风、龙卷风和地震。甚至家庭计算机用户应该备份程序和数据磁盘到安全的位置以防火或暴风雨的损害。

    内战和恐怖活动——在世界上的若干地方(战争、暴动、其他政治动荡是真实的危险。甚至在发达国家(然而(必须留心这些可能的破坏行动。

    科技故障——硬件和软件不总是按设计的去做。例如(灯火管制引起的太小的电流(可导致主存数据的丢失。

    人的过失——人的错误是不可避免的。数据入口错误是最常可能发生的。程序错误也经常出现。一些错误是有缺点的设计的结果(就像软件开发者用了另一个类似删除的命令。

    13.1.2;计算机安全措施

    近几年来(互联网使人们的生活改变了许多。人们使用电子邮件(通过IP电话和朋友交谈(从网上获取最新信息(在网络市场购物。与传统通信渠道相比(互联网有许多优势,花费实在(信息传送速度快(并且不受时间和地点的限制,互联网使用得越多(对互联网的安全就关注得越多。

    1;加密技术

    对称密钥加密(当事人双方要有一致的密钥。当AB要发送消息时(A用密钥将消息加密(B收到加密的消息后(用相同的(或最初的)密钥将消息解密。用对称密钥加密的优点在于它的加密和解密速度快(与相同安全标准下的非对称密钥加密术相比)

    对非对称密钥加密(当事各方都有一对密钥,公钥和私人密钥。公钥可自由使用(但只有密钥持有者拥有私人密钥。用公钥加密的消息只能用相应的私人密钥解密(反之亦然。AB发送消息时(A首先得到B的公钥将消息加密(然后发送给B B收到消息后(用他的私人密钥将消息解密。这种加密术的优点是人们可以自由获得公钥(因此从交换密钥问题中解脱出来。

    2;数字证书

    数字证书相当了电脑世界的身份证。当 一个人想获得数字证书时(他生成自己的一对密钥(把公钥和其他的鉴定证据送达证书授权机构(证书授权机构将核实这个人的证明(来确定申请人的身份。如果申请人确如自己所声称的(证书授权机构将授予带有申情人姓名、

    电邮件和申请人公钥的数字证书(并且该数字证书由证书授权机构用其私有密钥做了数字签名。当A要给B发送消息时(A必须得到B的数字证书(而非B的公钥。A首先核实带有证书授权机构公钥的签名(以确定是否为可信赖的证书。然后(A从证书上获得B的公钥(并利用公钥将消息加密后送给B

    3;认证

    认证是日常生活中的重要部分。缺少强有力的认证制约了电子商务的发展。写在纸上的合同、法律文件和官方信函仍是必要的。如果互联网用于电户商务(强有力的认证是一个关键要求。强有力的认证通常是建立在现代版的一次性密码本技术上的。例如(令牌用来代替昔日的一次性密码本(而且储存在小巧的卡片或磁盘上。

13.2 计算机病毒

    13.2.1;病毒是什么;

    计算机病毒之所以被称为病毒(是因为它们具有生物病毒的特性。计算机病毒从某台计算机到另一台计算机(类似生物病毒从某个人传染给另一个人。计算机病毒正是通常所说的恶意代码或恶意程序的一个例子。恶意程序的编写是对计算机系统实一系列伤害动作的。例如文件的删除、文件的毁坏(数据的窃取以及伤害不大但完全令人讨厌的玩笑。这些程序往往处于休眠和隐藏状态(直到一个激活事件产生。一旦受感染的程序被执行或者受感染的操作系统完成一项任务(病毒就会被激活。该病毒首先确定它应该在什么地方被执行(万一它不被执行(它将力图寻找并确认其他易受感染的程序、磁盘或系统。任何类似的对象将被感染。在确定了之后(易受感染的对象得到一份病毒的复制(该病毒将停止并且让正常操作继续进行。如果满足了所有的内部执行条件(病毒就发作。发作完成以后(该病毒要么恢复其状态(要么自行删除。该病毒将结束并允许继续正常运算。这一过程可能看起来是费时的并且对用户来说是很明显的(其实不然。当今计算机的运算如此之快(以至这一过程很容易不被注意并经常如此。

    13.2.2;计算机病毒有哪些类型;

    共有四种主要类型的病毒,壳型、侵入型、操作系统型和源代码型。壳型病毒,它将自己捆绑在主程序上(并不修改原始程序。壳型程序易于编写(这就是为什么大约一半的病毒属于这种类型。侵入型病毒,它侵害现有的程序(实际上(它把自己的一部份插入到主程序中。侵入型病毒难以编写(而且很难把它去掉同时不破坏主文件。壳型和侵入型病毒通常攻击的可执行文件——即带有.COM.EXE扩展名的文件—虽然数据文件也有某种危险。操作系统型病毒,它用自己的逻辑替换操作系统(OS)的某些部分。这种病毒很难编写(它具有这样的能力(一旦被引导(它就会完全控制整个系统。源代码型病毒,它是一种侵入式程序(在源程序被编译之前(这种程序被插入到例如用Pascal编写的源程序中。

    13.2.3;计算机病毒的影响

    计算机病毒给社会带来的影响可归结为以下几个方面,个人、企业、网络/联营公司/ 学以至整个社会。计算机病毒可以给个人用户制造很多麻烦(清除他硬盘里的数据(最小的影响可能包括对诸如游戏、电影等可以轻松修复的文件的删除或占用硬盘空间。计算机病毒对于一个企业来说会成为很大的威胁。企业也许会丢失重要的可能导致资产损失的文档。这会引发一连串的反应(如时间和金钱的浪费。与对企业的威胁类似(网络企业不止对联营公司造成伤害(而且还会将病毒扩散到各个不同的区域。实际上(全球网络是病毒扩散的重要途径。学校的网络很可能传播病毒(造成学生慌乱:而银行网络染上病毒甚至会导致系统瘫痪从而直接威胁到银行的运作。从更长远的角度来看(企业运作的瘫痪会对整个社会的正常运作造成影响。因为时间代表金钱(因此金钱的大量流失就很有可能会发生。航班被延误:资金无法回收,服务器停止工作等等。

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