To hire a group of experts, known as tiger teams or penetration teams, to see if they can break in is the usual way to test a system’s security. Hebbard et al. (1980) tried the same thing with graduate students. In the course of the years, these penetration teams have discovered a number of areas in which systems are likely to be weak. Below we have listed some of the more common attacks that are often successful. When designing a system, be sure it can withstand attacks like these.
Some Common Attacks
1- Request memory pages, disk space, or tapes and just read them. Many systems do not erase them before allocating them, and they may be full of interesting information written by the previous owner.
2- Try illegal system calls, or legal system calls with illegal parameters, or even legal system calls with legal but unreasonable parameters. Many systems can easily be confused.
3- Start logging in and then hit DEL, RUBOUT or BREAK halfway through the login sequence. In some systems, the password checking program will be killed and the login considered successful.
4- Try modifying complex operating system structures kept in user space. To open a file in many system's, the program builds a large data structure containing the file name and many other parameters and passes it to the system. As the file is read and written, the system sometimes updates the structure itself. Changing these fields can wreak havoc with the security.
5- Spoof the user by writing a program that types “login:” on the screen and go away. Many users will walk up to the terminal and willingly tell it their login name and password, which the program carefully records for its evil master.