Viruses

1
Viruses

• Juan Arriola
• CS-100

2
HISTORY

• Computers viruses first appeared with the credit
  of John von Neumann due to his studies on the
  self replication of mathematical automata in the
  1940s. Then the idea of viruses infecting
  computers and their programs emerged in the
  1970s leading to the first recorded case of the
  Brain virus at the University of Delaware in late
  1987.

3
What is a Virus?

• A computer virus is a piece of software designed
  and written to make additional copies of itself
  and spread, typically without user knowledge or
  permission.
• Some viruses display symptoms, and some cause
  damage to files in the system that have been
  infected.
• Since a virus is code that was not intentionally
  installed by the user, there are no "good"
  viruses.
• When a virus finds itself in a different
  environment than that for which it was written, a
  non-destructive virus can become destructive.

4
There are 4 main classes of viruses

• Boot-sector viruses
• Program file viruses
• Multi-partite viruses
• Macro viruses

5
How Do Computers Become Infected?

• Viruses can be hidden in programs available on
  floppy disks or CDs, hidden in email attachments
  or in material downloaded from the web.
• Once the virus is active on the computer, it can
  copy itself to (infect) other files or disks as
  they are accessed by the user.

6
How do they work?

• Viruses work in a multitude of different ways
• They can damage important operating system files
• After infecting your computer, they spread
  themselves to other computers by using your
  Internet connection when youre online.
• They can collect important information about the
  users of the computers the viruses infect and
  send it back to the author

7
How do they work?

• They can send emails (without you even opening
  your email program) to everyone in your address
  book from you that contain the virus.
• They can also spread through other connections
  that your computer maintains to the Internet.
• They can produce annoying pop-up advertisements
  (even when youre not on the Internet), they can
  crash websites, and pretty much anything else you
  can imagine.

8
How do I get infected?

• Most viruses infect computers through application
  files of some kind (attachment files with a .EXE
  or .SCR extension are the most typical). The user
  of the computer (you) has to physically open the
  application file.
• Most viruses come through as an attachment to an
  email message. However, since 2003, viruses have
  become more advanced and can actually infect your
  computer through open connections to the Internet.

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Why do people write them?

• People can write viruses to collect important
  information (like credit card numbers) for
  malicious intent, to see how many computers they
  can infect and, in some cases, people write
  viruses to crash websites (like the Blaster worm
  of August 2003 which was written to crash
  Microsofts website).

10
What are some common computer viruses?

• Netsky
• Blaster
• Sobig
• Melissa

• Lovletter
• Chernobyl
• Klez
• Nimda
• Lirva

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Viruses Names

• NetskyWin32.Netsky.ABWin32.Netsky.ACWin32.Netsk
  y.BWin32.Netsky.CWin32.Netsky.DWin32.Netsky.PW
  in32.Netsky.QWin32.Netsky.SWin32.Netsky.TWin32.
  Netsky.WWin32.Netsky.Y
• MsblastWin32.Msblast.A

• BugBearWin32.BugBear.A_at_mmWin32.BugBear.B_at_mmK
  lezWin32.Klez.E_at_mmWin32.Klez.H_at_mmWin32.Klez.D_at_
  mmWin32.Klez.A_at_mm
• CodeRedWin32.IISWorm.CodeRed.F

12
Safe Computing practices!

• Anti-Virus software
• Scan your computer on a regular basis
• Update your Anti-Virus Software on a regular
  basis
• Backup your files on a regular basis

• Scan Protect Floppy Disks
• Scan E-mail Attachments
• Beware of E-mail Attachments from unknown sources
  
• Be Alert

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Resources Cited

• www.bullguard.com
• www.sophos.com
• www.mcafee.com
• http//www.trendmicro.com