(2) An interception means that some unauthorized party has gained access to an asset. The outside party can be a person, a program, or a computing system. Examples of this type of failure are illicit copying of program or data files, or wiretapping to obtain data in a network. While a loss may be discovered fairly quickly, a silent interceptor may leave no traces by which the interception can be readily detected.

　　(2)截取是指某一非特许用户掌握了访问资源的权利。外界用户可以是一个人、一个程序或一个计算机系统。这种威胁的例子如程序或数据文件的非法拷贝，或私自接线入网去获取数据。数据丢失可能会很快被发现，但很可能截取者并不留下任何容易检测的痕迹。

　　(3) If an unauthorized party not only accesses but tampers with an asset, the failure becomes a modification. For example, someone might modify the values in a database, alter a program so that it performs an additional computation, or modify data being transmitted electronically. It is even possible for hardware to be modified. Some cases of modification can be detected with simple measures, while other more subtle changes may be almost impossible to detect .

　　(3)如果非授权用户不仅可以访问计算机资源，而且可以篡改资源，则威胁就成为修改了。例如，某人可以修改数据库中的值，更换一个程序，以便完成另外的计算，或修改正在传送的数据，甚至还可能修改硬件。某些情况下可以用简单的测量手段检测出所做的修改，但某些微妙的修改是不可能检测出来的。

　　(4) Finally, an unauthorized party might fabricate counterfeit objects for a computing system. The intruder may wish to add spurious transactions to a network communication system. or add records to an existing data base . Sometimes these additions can be detected as forgeries, but if skillfully done, they are virtually indistinguishable from the real thing.

　　(4)最后，非授权用户可以伪造计算机系统的一些对象。入侵者妄图向网络通信系统加入一个假的事务处理业务，或向现有的数据库加入记录。有时，这些增加的数据可以作为伪造品检测出来，但如果做得很巧妙，这些数据实际上无法与真正的数据分开。

　　These four classes of interference with computer activity-interruption, interception, modification, and fabrication-can describe the kinds of exposures possible[2].

　　这四种对计算机工作的干扰——中断，截取，修改或伪造——表明了可能出现的几种威胁类型。

[1]  [2]