Sample Final

These are sample questions that are very similar to the ones I will ask on the final.

  1. In computer security, a Trojan horse is:
    1. A program that has components distributed over many systems, and is used to launch denial of service attacks
    2. A program that absorbs all available resources of a particular type
    3. A program with an overt, known purpose and a covert, unknown (and probably undesireable) purpose
    4. A program that blocks any incoming spam emails

  2. How does the Clark-Wilson model require authentication of users to be done?
    1. A trusted user must vouch for the new user
    2. Two-factor authentication must be used
    3. If passwords are used, they must be at least 12 characters long, and use a mixture of letters, digits, and other characters
    4. None of the above

  3. Which of the following does the Needham-Schroeder protocol require?
    1. A trusted third party
    2. A public key cryptosystem
    3. A certificate authority to identify the users
    4. A connection to the Internet
  4. Consider a system that used the Bell-LaPadula model to enforce confidentiality and the Biba model to enforce integrity.
    1. If the security classes were the same as integrity classes, what objects could a given process (with some security class that also served as its integrity class) access?
    2. Why is this scheme not used in practice?

  5. What is a certificate? What is it used for?

  6. The following routine reads a file name from the standard input and returns its protection mode. It treats the argument as a file name, and returns the protection mode of the file as a short integer. Identify three non-robust features of this routine, and state how to fix them.
    /* return protection mode of the named file */
    short int protmode(void)
        struct stat stbuf;
        char inbuf[100];

        stat(inbuf, &stbuf);

  7. Show how ACLs and C-Lists are derived from an access control matrix.

  8. Discuss the revocation problem with respect to access control lists and capabilities. How might one efficiently implement a command to revoke access to an object by one particular user?

  9. Why do some organizations use a DMZ in their network configuration, rather than simply filtering traffic and allowing connections intended for the web and email servers to pass through the firewall?

You can also obtain a PDF version of this. Version of November 28, 2016 at 12:54PM