Lec 3 - Program Security

There are 2 type of Vulnerabilities :-

1. Secure Program
2. Malicious Code

Secure Program

* An assessment of security can also be influenced by someone’s general perspective on software quality. For example, if your manager’s idea of quality is conformance to specifications, then she might consider the code secure if it meets security requirements, whether or not the requirements are complete or correct. This security view played a role when a major computer manufacturer delivered all its machines with keyed locks, since a keyed lock was written in the requirements. But the machines were not secure, because all locks were configured to use the same key! Thus, another view of security is fitness for purpose; in this view, the manufacturer clearly had room for improvement.

Malicious Code

* Malicious code (also called vandals) is a new breed of Internet threat that cannot be efficiently controlled by conventional antivirus software alone. In contrast to viruses that require a user to execute a program in order to cause damage, vandals are auto-executable applications.

Malicious code can take the form of:

* Java Applets
* ActiveX Controls
* Scripting languages
* Browser plug-ins
* Pushed content

- Once inside your network or workstation malicious code can enter network drives and propagate. They can also cause network and mail server overload by sending email messages, stealing data and passwords, deleting document files, email files or passwords, and even re-formatting hard drives.

Examples of malicious codes:

* Trojan Horse – a program which performs a useful function, but also performs an unexpected action as well.
* Virus – a code segment which replicates by attaching copies to existing executables.
* Worm – a program which replicates itself and causes execution of the new copy.
* Logic bomb – malicious code that activates on an event (e.g., date).
* Trap Door (or Back Door) – undocumented entry point written into code for debugging that can allow unwanted users.

Viruses

* A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.