- Perverse software is a program which causes hindrances in other programs execution in such a way resulting in modification or complete destruction of data without the user’s intention or even sabotaging the operational system.
- Perverse Software is also known as Malicious software or Malware.
- It is a type of software that is designed to secretly access a computer system, without the owner‘s consent, and damage the system. The impact can be as damaging as shutting down a business, pulling down computer network or significantly impacting regular use of individual computer systems etc. The damage done can vary from something as little as changing the author’s name in a document to full control of one‘s machine without the ability to easily find out.
- Most malware requires the user to initiate its operation. For example, sending infectious attachments (it acts when users downloads them and runs the attachment) in e-mails, browsing a malicious website that installs software after the user clicks ok on a pop-up, and from vulnerabilities in the operating system.
- Early infectious programs, such as Internet Worm and MS DOS viruses, were written as experiments and were largely harmless or at most annoying.
- With the spread of broadband Internet access, malicious software has been designed for a profit, for forced advertising.
- Here the malware keeps track of user‘s web browsing, and pushes related advertisements.
Types of Malicious Software
- There are several typical types of malicious software. These are – Computer virus, Computer Worm, Trojan horse, Rootkits, Spyware etc.
(a) Computer Virus :
- Computer virus is a small software program that is designed to enter a computer without users‘ permission or knowledge, to interfere with computer operation and to spread from one computer to another.
- A computer virus needs to attach itself to a document or program to infect other computers or programs.
- Some viruses do little but replicate while others can cause severe harm or adversely effect program and performance of the system.
- They can destroy files, software, program applications, and cause the loss of data.
- There are various types of computer virus that can be classified by their origins, techniques of attack, modes of spreading, forms of infections, hiding locations and the kind of damage caused.
- Examples of computer viruses are: Randex, Melissa.A and Trj.Reboot Computer
(b) Worm :
- Worm is a program that is very similar to a virus. It has ability to self replicate.
- It actively spreads itself over the network, copies itself from one disk drive to another or copies using email.
- It does not need user action to start it unlike virus.
- Examples of worms include: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson.
(C) Trojan Horse :
- When a program is disguised as something interesting and desirable, users are tempted to download and install it on their machine, without knowing what it does.
- This is when it does the damages by deleting files from the system or by further installing unwanted software.
- This is the typical technique of Trojan horse.
- For example, a file called “saxophone.wav file” on the computer of user who’s interested in collecting sound samples may actually be a Trojan Horse.
- Trojan Horses unlike viruses do not reproduce by infecting other files, nor do they self-replicate like worms, but they are extremely dangerous to users computer’s security and personal privacy.
- They make a computer susceptible to malicious intruders by allowing them to access and read files.
(d) Rootkits :
- This is a technique using which the malware remains concealed in the system, and continues to do the damage in a concealed manner.
- Rootkits can prevent a malicious process from being visible (ex Task Bar in Windows operating system) in the list of running applications.
- Rootkits normally attempt to allow someone to gain control of a computer system.
- These programs are usually installed by trojans and are generally disguised as operating system files.
(e) Trap doors :
- This is a way of bypassing normal authentication procedure (windows/ operating system user name and password) to access a system.
- Once a system is compromised (impacted by) by malware, one or more backdoors may be installed for easier future access to the system.
(f) Logic/Time Bombs :
- Logic Bombs are not programs in their own right but rather camouflaged segments of other programs.
- They are not considered viruses because they do not replicate. But their objective is to destroy data on the computer once certain conditions have been met.
- Logic bombs go undetected until launched, and the results can be destructive.
- For example, some malicious programs are sot off during days such as April Fools Day or Friday the 13th.
(g) Keystroke Loggers :
- This is a program, once installed on the system, which intercepts the keys when entering the password or the Credit Card number while shopping online.
- This can be used for Credit Card fraud. Data-stealing
- This is a web threat that results in stealing of personal and proprietary information to be used for commercial gains either directly or via underground distribution.
- Some popular examples of recent data-stealing cases are – steal and sell large number of credit card numbers from businesses such as TJX, OfficeMax, Sports Authority etc.
Prevention from Malicious Software :
- Block unwanted email viruses by installing a spam filter and spam blocker.
- When browsing the internet, always watch what one clicks and installs.
- Do not simply click OK to dismiss pop-up windows. Install anti-virus software; scan and update regularly. It can, in most cases, remove and prevent viruses, worms, trojans, and (depending on the software) some spyware.
- Install anti-spyware/anti-adware; scan and update regularly. It will remove and (depending on the software) prevent future adware and spyware.
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