BALGLInstitute of Information Technology

A Presentation on Computer Virus

Rohitash kumarRahul BaghlaRavikant Verma

Group Members :-

Group Name:- G3

Contents :-

What is a virus

Types of virus

Indications of Virus Attack

Creating a virus Protecting from virus

Remove some common virus

Conclusion

What is a virus?

• A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user.

• A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD, or USB drive.

Types of Viruses

Trojan Horse

Worms

Boot sector Virus

Macro Virus

Memory Resident Virus

Root kit Virus

Polymorphic Virus

Logic Bombs

What are Trojan Horses ?

• A Trojan horse is a computer program that is hiding a virus or other potentially damaging program. A Trojan horse can be a program that purports to do one action when, in fact, it is performing a malicious action on your computer. Trojan horses can be included in software that you download for free or as attachments in email messages.

What is a Worm?

• A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computer terminals on the network) and it may do so without any user intervention.

• Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

Boot Sector Virus :- A boot sector virus infects boot sector of computers. During system boot, boot sector virus is loaded into main memory and destroys data stored in hard disk.Macro Virus :-

Macro viruses are viruses that use another application's macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents.

Memory Resident Virus :-Memory Resident Viruses reside in a computers

volatile memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it's initiating program closes.

Root kit Virus :-A root kit virus is an undetectable virus which

attempts to allow someone to gain control of a computer system. The term root kit comes from the Linux administrator root user. These viruses are usually installed by Trojans and are normally disguised as operating system files.

Polymorphic Virus :-Polymorphic viruses contain complex

instructions that enable them to mutate into new and different viruses.This makes it impossible for anti-viruses to find them using string or signature searches (because they are different in each encryption). The virus then goes on creating a large number of copies. 

Logic Bombs :-Logic bombs are often attached to a working

program but do not replicate. They are only executed when a certain predefined condition is met. Their objective is to destroy data on the computer once certain conditions have been met.

Indications of Virus Attack

Computer runs slower then usual Computer no longer boots up Screen sometimes flicker PC speaker beeps periodically System crashes for no reason Files/directories sometimes disappear

How To Create a Virus

As we know, Virus is nothing it is just a program which are created for malicious purpose. If it occurs in a system & user is unaware of from it then it can destroy or damage our system.

Open Notepad and write the following code

@Echo off Start virus.bat virus.bat save it as .bat and run it.

It will hang our computer & we have to shut down the computer forcibly...

Continued..

Protection from Virus

Install reliable anti-virus software

Update our anti-virus software regularly

Don't automatically open attachments

Scan all incoming email attachments

Delete chain emails and junk email

Be careful when downloading files from the Internet

Always scan new files for viruses before we use them

Backup our files on a regular basis

If our computer is on a network, make sure we have

security steps in place to prevent unauthorized users

putting files on our computer

Take care using USB flash cards, CDs, zip and floppy

disks

Continued…

Examples of risky file types :-

• The following file types should be treated with suspicion and be confirmed with the sender before being opened:– .exe– .bat– .vbs

Remove Some Common Viruses

• We can remove some of the common viruses without help of any antivirus Program.

• e.g.- New Folder.exe

• Autorun.inf ( from PDs etc)

New Folder.exe

• It looks just like an folder but actually it is a .exe file.

• Try to deleting the file.• It will delete if you haven’t

executed it, if you’re unable to delete it.

• Go to Task manager ( by pressing ctrl+shift+esc )

Go to Process Tab and try finding that the process for the exe file and end the process. Then Go to the same folder containing the exe file and delete it. Then Open Search and try finding the .exe files of same size and delete them all.

Continued …

Removal of Autorun.inf

• Open Run dialog Box. Type in “CMD” press ENTER.

Continued …

• The Command Prompt will Open Now. In Command prompt go to the drive containing Autorun.inf

• Now Type In “ attrib –h –s –a” and press enter.

Continued …

• This will remove drives attributes for all Hidden, System files.

• Now Type “ Del autorun.inf” and press ENTER.

• The Virus has been Successfully Removed.

“It is good to be aware of viruses rather than being

sorry…..”

Thank You !!

Any Queries ??