1. Information Systems CS-507 Lecture 32

2. Physical Intrusion The intruder could physically enter an organization to steal information system assets or carry out sabotage. e.g. Intruder might try to remove hard disks.

3. Logical Intrusion The person might be trying to have an unauthorized access to the system. The purpose could be Damaging or stealing data Installation of bugs / viruses Wire tapping -- Spying on communication within the organization

4. Viruses It may be benign (gentle) or have a negative effect, such as causing a program to operate incorrectly or corrupting a computer's memory. The term virus is a generic term applied to a variety of malicious computer programs that send out requests to the operating system of the host system under attack to append the virus to other programs.

5. Attacking Targets Executable program files The file-directory system, which tracks the location of all the computers files Boot and system areas, which are needed to start the computer Data files

6. Worms Worm typically exploits security weaknesses in operating systems configurations to propagate itself to the host systems.

7. Virus Vs. Bug Bug is caused by improper application of programming logic. Virus is the external threat which is not a malfunction of the software. We have to secure our systems in such fashion that possibilities are reduced. The developer has to ensure that the bugs in the final product are not existing and have been removed before usage.

8. Sources of Transmission Virus or worms are transmitted easily from the internet by downloading files through computers web browsers. Viruses are also transmitted as attachments to e-mail, so that when word processing software opens the attachments, the system becomes infected, if it is not using anti-virus scanning software to review unopened attachments. Other methods of infection occur from files received though online services, computer bulletin board systems, local area networks. Even shrink-wrapped software that the user may buy from a retail store can be infected with a virus.

9. Boot sector Virus The boot sector is part of hard disk which helps computer to start up. If the boot sector is infected, the virus can be transferred to the operating system and application softwares.

10. Trojan horse A Trojan horse is a malicious program that is disguised as or embedded within legitimate software. Examples are –Logic bomb – Trojan horses are triggered on certain event, e.g. when disc clean up reaches a certain level of percentage –Time bomb – Trojan horse is triggered on a certain date.

11. Virus and worm controls Management Controls -- By having sound policies and procedures in place, and Technical Controls -- By technical means, including antivirus software.

12. Management Controls USB port enabled devices should not be used until it has been scanned on a stand-alone machine that is used for no other purpose and is not connected to the network.

13. Management Controls Have vendors run demonstrations on their personal machines. Scan before any new software is installed. Insist that field technicians scan their disks on a test machine before they use any of their disks on the system.

14. Management Controls Ensure all servers are equipped with an activated current release of the virus-detection software. Ensure bridge, router and gateway updates are authentic. Exercise an effective back up plan. Educate users so they will heed these policies and procedures.

15. Technical controls Use boot virus protection (i-e., built-in, firmware-based virus protection). Use remote booting, local hard drive of the system is not used for the boot up process. Use a hardware-based password. Use write-protected tabs on diskettes. Ensure insecure protocols are blocked by the firewall from external segments and the internet.