Explain the difficulty of creating a computer virus and discuss the frequency with which this happens.
The degree of virus was determined by the complexity of the logic that the user or creator want to give and want to do. The programming language of choice for developing virus is the Assembler as the so called high-level languages such as Turbo Pascal, C, database managers, etc., are designed to produce software applications.
Using different techniques to create complex virus the person succeeds in creating a destructive weapon for computer users, among these techniques we have the Fast infector virus which when is active in memory not only infects programs when executed but those who are simply open to be read.
The Slow infector virus infects only files as they are executed, modified or created, but with one caveat can also use the technique of fast infector but without the instruction of alteration or damage immediately to open a file. Parse strategy is to direct the virus to infect occasionally, for example every 10 times the performance of a program.
Companion Mode is when the virus instead of modifying an existing file creates a new one with the same name at the time to infect, going unnoticed by the user. Armored style is a very peculiar form of programming, where the creator program a series of routines that used as covers or shields, the file containing the virus so that it cannot easily be "tracked" much less disassembly. A Stealth virus is one that when activated hides the modifications made to files or boot sectors are infected. Polymorphic viruses, their values of programming are changed sequentially each time are autoencriptan, so that their chains are not the same. The polymorphic virus produces multiple but different copies of itself, maintaining its operational microcode viral.
Viruses are small programs, set intentionally designed to disrupt the normal functioning of computers. They are installed without user consent and run autonomously to self-replicate and continue its spread. The creation of these viruses is illegal in most countries of the worlds which have created laws with heavy penalties for the creators of these viruses.
In other to protect companies and personal data business and people use some security measures such a Firewalls which is “a combination of hardware and software that acts as a filter between a private network and external computer or network” (Bidgoli, 2012, p. 82).
Although there are laws and technological advances to prohibit and prevent the creation of these viruses, now a days, there are unscrupulous people who most often create these and more complex viruses making this a more difficult task to eradicate them. “It is sad that some people in our world have found the internet to be a useful tool for perpetrating crimes, conducting terrorism, and even waging war” (Schneider, 2010, p. 340).
Explain the difference between a virus and a worm, and describe how the respective threat levels compare.
Nowadays, “virus programmers tend to combine different types of virus or worms with different techniques, thus making difficult – not to say artificial –any attempt to classify them properly.” (Filiol, 2005, p. 122).
A computer virus is a small program designed to alter the way a computer works without the permission or knowledge of the user. A virus must have two characteristics must be able to execute itself, often places its own code into the path of execution of another program and must be able to replicate. For example, it may replace other executable files with a copy of the infected file. Viruses can infect desktop, laptop computers and network servers, virus creators take into account characteristics such as size, symbols, and data from the creator to hide inside the machines and avoid detection. Therefore, the virus re-orients the disk read, modify its size in the directory and change some parts of its code to avoid being detected and destroyed.
In the other hand, Worms are programs that replicate themselves from system to system without using a file to do so. In this they differ from viruses that need to be extended by an infected file. Although the worms are usually found within other files, often Word or Excel documents, there is a difference in the way that worms and viruses use the hosts file. Usually the worm will generate a document that contains the worm macro inside.
The entire document will travel from one computer to another using fragments of user own posts and thus spreading to the four winds its contents, with damage added to propagate moral and personal communications sometimes highly confidential, so that the entire document should be regarded as a worm.
Once lodged in a computer, the worms can do everything from displaying annoying messages while working to simply mix all the contents of the hard drive to make it unusable. They also often seek to disable antivirus programs and "firewalls" installed before leaving the machine unprotected new attacks. We have to keep in consideration that “Viruses require hosts, by definition, while Worms do not require a host because are typically a mainframe problem.” (Stang, 1991, p. 2).
Address the questions: Are non-Microsoft operating systems less prone to virus attack? Why or why not?
Windows operating systems is more likely to be infected with viruses, “Often, Windows viruses are part virus and part Trojan.” (Grimes, 2001, p. 105). The fact is to infect a Windows PC the only thing you need is to be connected to the network as the platform allows the auto execution. While others operating systems have to be authorize and execute by the user such a Linux or UNIX, making this more difficult for the virus to get into the PC without authorization, if a user see an unknown Script can decide between executed or not, if the script is not executed will only occupied space into the PC without major harm. According to Channelle, Sicam and Thomas, “Linux fans constantly note that viruses can’t cause problem on their system because the core of the operating system is well protected.” (Channelle, Sicam, & Thomas, 2009, p. 185).

References
Bidgoli, H. (2012). MIS2. Boston, MA: Course Technology Cengage Learning.
Channelle, A., Sicam, J., & Thomas, K. (2009). Beginning Ubuntun Linux: From Novice to Professional, Fourth Edition . New York : Springer-Verlang .
Filiol, E. (2005). Computer viruses: from theory to appications. New York : Springer-Verlag.
Grimes, R. A. (2001). Malicious Mobile Code: Virus Protection for Windows. Sebastopol, CA: O'Reilly and Associates, Inc. .
Schneider. (2010). Electronic Commerce. Mason, OH: Cengage Learning.
Stang, D. J. (1991). Computer Virus Survival Guide. Washington, DC: National Computer Security Association.