ARPANET, the scientific/military network that preceded the modern internet.
Computer Viruses and Worms
• Virus through the Internet
• Virus Languages
• Trojan Horses
• Melissa virus
• I LOVE YOU VIRUS
• CODE RED (WORM)
• SYMPTOMS OF AN INFECTION
• Protection measures
• Computer virus have become today’s headline news
• With the increasing use of the Internet, it has
become easier for virus to spread
• Virus show us loopholes in software
• Most virus are targeted at the MS Windows OS
Virus : A true virus is capable of self replication
on a machine. It may spread between files or
disks, but the defining character is that it can
recreate itself on it’s own with out traveling to
a new host
Virus through the Internet
• Today almost 87% of all viruses are spread
through the internet
• Transmission time to a new host is relatively
low, on the order of hours to days
• “Latent virus”
Unix Shell Scripts
Basically any language that works on the system
that is the target
1. The Creeper Virus occurred in 1971 on
ARPANET was written by Bob Thomas at the
BBN Technologies lab.
2. Elk Cloner was the first personal computer
virus to appear in 1982 written by Richard
3. Brain The first IBM PC virus created in 1986
by the Farooq Alvi Brothers in Lahore,
• There are estimated 30,000
computer viruses in existence
• Over 300 new ones are created each
• First virus was created to show
loopholes in software
• Moves around in e-mail messages
• Usually replicate itself by automatically
mailing itself to dozens of people in the
victim’s email address book.
• Example “MELISSA VIRUS”
• Example “I LOVE YOU VIRUS”
• Small piece of software that uses computer
networks and security holes to replicate
• Copy itself to the new machine using the
security hole and start replicating.
• First worm released on the Internet was called
Morris worm, it was released on Nov 2, 1988.
• Example “CODE RED”
• A simple computer program
• It claim to be a game
• Erase your hard disk
• No way to replicate itself.
• Leaks information
• Usually does not reproduce
Hoaxes . . .
Too Good to be True
You receive an e-mail telling you that:
• There is a problem with your PayPal account. Your
personal information is needed to correct it.
• The government has discovered a problem with your
tax records. Your personal information is needed to
• You just won a lottery that you didn't even know that
you had entered. Send a handling fee to receive your
Melissa Virus (March 1999)
Melissa virus spread in Microsoft Word documents sent
How it works ?
• Created the virus as word document
• Uploaded to an internet newsgroup
• Anyone who download the document and opened it
would trigger the virus.
• Send friendly email messages to first 50 people in
person’s address book.
• Melissa Virus was the fastest spreading virus
• Forced a number of large companies to shut
down their e-mail systems.
I Love You Virus (May,2000)
• Contained a piece of code as an attachment.
• Double Click on the attachment triggered the
• Sent copies of itself to everyone in the victim’s
• Started corrupting files on the victim’s
Code Red (Worm)
• Code Red made huge headlines in 2001
• It slowed down internet traffic when it began
to replicate itself.
• Each copy of the worm scanned the internet
for Windows NT or Windows 2000 that don’t
have security patch installed.
• Each time it found an unsecured server, the
worm copied itself to that server.
Code Red Worm
Designed to do three things
Replicate itself for the first 20 days of each
Replace web pages on infected servers with a
page that declares “Hacked by Chinese”
Launch a concreted attack on the White
House Web server
Symptoms of Infection
• Programs take longer to load than normal.
• Computer’s hard drive constantly runs out of
• The floppy disk drive or hard drive runs when
you are not using it.
• New files keep appearing on the system and
you don’t know where it come frm.
Symptoms of Infection Cont..
• Strange sounds or beeping noises come from
• Strange graphics are displayed on your
• Unable to access the hard drive when booting
from the floppy drive.
• Program sizes keep changing.
• Proper configurations
• Run only necessary programs
• Anti-virus software
• Have seen how viruses show us a loophole in
• Most viruses show that they can cause great
damage due to loopholes in programming
• Always backup your data.
• Keep up-to-date on new Anti virus software.
• Simply avoid programs from unknown