Trojan horses: They are programs that appear to have one function but actually perform another function.Thus, signature of each copy will vary, and a virus scanner will find it difficult to locate it.
Damage caused by malicious software
o Virus can destroy file allocation tables (FAT) and lead to the corruption of an entire file system, resulting in the need to fully reinstall and reload the system.Parasitic Virus: It attaches itself to executable files and replicates, when the infected program is executed, by finding other files to infect.Polymorphic Virus: Creates copies that are functionally equivalent but have distinctly different bit patterns.Boot Sector Virus: It infects a boot record and spreads when a system is booted from the disk containing the virus.Viruses: They are programs that modify other programs on a computer by inserting copies of themselves.pUY
A virus tries to take control of computer system it has infected at the first opportunity; it makes copies of itself and try to carry harmful task written in its program.o Some worms scan for passwords and other loopholes and then send the information back to the attacker.The modern - day Trojan horses resemble a program that the user wishes to run - a game, a spreadsheet, or an editor.While the program appears to be doing what the user wants, it is also doing something else unrelated to its advertised purpose, and without
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the user's knowledge.Viruses:
o Need to have some host program, (of which they are a part), executed to activate them.Jas!Types of Viruses:
0?1.2.3.4.