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Cyber Crime

Today’s Lecture:

Cyber Crime

• To find out about several types of crimes that occur over cyber space (i.e. the Internet)
• To familiarize ourselves with with several methods that can be used to minimize the ill effects of
those crimes

39.1 07 February 2000

• Users trying to get on to the Web sites of Yahoo, couldn’t!
• Reason: Their servers were extremely busy!
• They were experiencing a huge number of hits
• The hit-rate was superior to the case when a grave incident (e.g. 9/11) occurs, and people are trying
to get info about what has happened
• The only problem was that nothing of note had taken place!

What was going on?

• A coordinated, distributed DoS (Denial of Service) attack was taking place
• Traffic reached 1 GB/s; many times of normal!
• In the weeks leading to the attack, there was a noticeable rise in the number of scans that Internet
servers were receiving
• Many of these scans appeared to originate from IP addresses that traced back to Korea, Indonesia,
Taiwan, Australia

Three Phases of the DoS


1. Search for Drones

• The attackers set about acquiring the control over the computers to be used in the attack …
• by scanning – using e.g. Sscan SW – a large numbers of computers attached to the Internet
• Once a computer with a weak security scheme is identified, the attackers try a break-in
• Once conquered, that computer – called a drone – will be used to scan others

2. Arming the Drones

• After several drones have been conquered, the DoS SW is loaded on to them
• Examples: Tribal Flood Network, Trinoo, TFN2K
• Like a time-bomb, that SW can be set to bring itself into action at a specified time
• Alternatively, it can wait for a commencement command from the attacker

3. The Actual Attack

• At the pre-specified time or on command, the SW implanted on all of the drones wakes-up and
starts sending a huge number of messages to the targeted servers
• Responding to those messages overburdens the targeted servers and they become unable to perform
their normal functions

Neutralizing the Attack

• The engineers responsible for monitoring the traffic on the Yahoo Web sites quickly identified the
key characteristics of the packets originating from those drones
• Then they setup filters that blocked all those packets
• It took them around 3 hours to identify and block most of the hostile packets
• BTW, the sender’s IP address can be spoofed, making it impossible to block the attack just by
blocking the IP addresses

The Aftermath

• None of the Yahoo computers got broken-into; The attackers never intended to do that
• None of the user data (eMail, credit card numbers, etc.) was compromised
• Ill-effects:
– Yahoo lost a few million’s worth of business
– Millions of her customers got annoyed as they could not access their eMail and other info from the
Yahoo Web sites

Who Done It?

• The DoS SW is not custom SW, and can be downloaded from the Internet. Therefore, it is difficult
to track the person who launched the attack by analyzing that SW
• After installing the DoS SW on the drones, setting the target computer and time, the attackers
carefully wipe away any info on the drone that can be used to track them down
• End result: Almost impossible to track and punish clever attackers

How to stop DoS attacks from taking place?

• Design SW that monitors incoming packets, and on noticing a sudden increase in the number of
similar packets, blocks them
• Convince system administrators all over the world to secure their servers in such a way that they
cannot be used as drones
• BTW, the same type of attack brought down the CNN, Buy, eBay, Amazon Web sites the very next
day of the Yahoo attack

39.2 DoS Attack: A Cyber Crime

• DoS is a crime, but of a new type - made possible by the existence of the Internet
• A new type of policing and legal system is required to tackle such crimes and their perpetrators
• Internet does not know any geographical boundaries, therefore jurisdiction is a key issue when
prosecuting the cyber-criminal

Cyber crime can be used to …

• Damage a home computer
• Bring down a business
• Weaken the telecom, financial, or even defense-related systems of a country


• In 1997, blackouts hit New York City, Los Angeles
• The 911 (emergency help) service of Chicago was shut down
• A US Navy warship came under the control of a group of hackers
• What was happening? A cyber attack!
• All of the above did not happen in reality, but in a realistic simulation
• The US National Security Agency hired 35 hackers to attack the DoD’s 40,000 computer networks
• By the end of the exercise, the hackers had gained root-level (the highest-level!) access to at least 3
dozen among those networks


A clear and present threat as well opportunity for all of the world’s armed force!

39.3 More cybercrimes …

Mail Bombing

• Similar in some ways to a DoS attack
• A stream of large-sized eMails are sent to an address, overloading the destination account
• This can potentially shut-down a poorly-designed eMail system or tie up the telecom channel for
long periods
• Defense: eMail filtering


• Hackers are always trying to break-in into Internet-connected computers to steal info or plant
malicious programs
• Defense: Intrusion detectors

Credit Card Fraud

• A thief somehow breaks into an eCommerce server and gets hold of credit numbers and related
• The thief then uses that info to order stuff on the Internet
• Alternatively, the thief may auction the credit card info on certain Web sites setup just for that
• Defense: Use single-use credit card numbers for your Internet transactions

Software Piracy

• Using a piece of SW without the author’s permission or employing it for uses not allowed by the
author is SW piracy
• For whatever reason, many computer users do not consider it to be a serious crime, but it is!
• Only the large rings of illegal SW distributors are ever caught and brought to justice
• Defense: Various authentication schemes. They, however, are seldom used as they generally
annoy the genuine users

Industrial Espionage

• Spies of one business monitoring the network traffic of their competitors
• They are generally looking for info on future products, marketing strategies, and even financial
• Defense: Private networks, encryption, network sniffers

Web Store Spoofing

• A fake Web store (e.g. an online bookstore) is built
• Customers somehow find that Web site and place their orders, giving away their credit card info in
the process
• The collected credit card info is either auctioned on the Web or used to buy goods and services on
the Web

39.4 Viruses

• Self-replicating SW that eludes detection and is designed to attach itself to other files
• Infects files on a computers through:
– Floppy disks, CD-ROMs, or other storage media
– The Internet or other networks
• Viruses cause tens of billions of dollars of damage each year
• One such incident in 2001 – the LoveBug virus – had an estimated cleanup/lost productivity cost of
US$8.75 billion
• The first virus that spread world-wide was the
Brain virus, and was allegedly designed by someone
in Lahore

One Way of Classifying Viruses

• Malicious
– The type that grabs most headlines
– May destroy or broadcast private data
– May clog-up the communication channels
– May tie-up the uP to stop it from doing useful work
– May display an annoying, but harmless message
– May hop from one computer to another while searching for and destroying malicious viruses

Anatomy of a Virus

• A virus consists of 2 parts:
• Transmission mechanism
• Payload

Transmission Mechanism

• Viruses attach themselves to other computer programs or data files (termed as hosts)
• They move from one computer to another with the
hosts and spring into action when the host is
executed or opened


• The part of the virus that generally consists of malicious computer instructions
• The part generally has two further components:

– Infection propagation component:
• This component transfers the virus to other files residing on the computer
– Actual destructive component:
• This component destroys data or performs or other harmful operations

Commonsense Guidelines

• Download SW from trusted sites only
• Do not open attachments of unsolicited eMails
• Use floppy disks and CDROMs that have been used in trusted computers only
• When transferring files from your computer to another, use the write-protection notches
• Stay away from pirated SW
• Regularly back your data up
• Install Antivirus SW; keep it and its virus definitions updated

Antivirus SW

• Designed for detecting viruses & inoculating
• Continuously monitors a computer for known viruses and for other tell-tale signs like:
– Most – but, unfortunately not all – viruses increase the size of the file they infect
– Hard disk reformatting commands
– Rewriting of the boot sector of a hard disk
• The moment it detects an infected file, it can automatically inoculate it, or failing that, erase it

39.5 Other Virus-Like Programs

• There are other computer programs that are similar to viruses in some ways but different in some
• Three types:
– Trojan horses
– Logic- or time-bombs
– Worms

Trojan Horses

• Unlike viruses, they are stand-alone programs
• The look like what they are not
• They appear to be something interesting and harmless (e.g. a game) but when they are executed,
destruction results

Logic- or Time-Bombs

• It executes its payload when a predetermined event occurs
• Example events:
• A particular word or phrase is typed
– A particular date or time is reached


• Harmless in the sense that they only make copies of themselves on the infected computer
• Harmful in the sense that it can use up available computer resources (i.e. memory, storage,
processing), making it slow or even completely useless
• Designing, writing, or propagating malicious code or participating in any of the fore-mentioned
activities can result in criminal prosecution, which in turn, may lead to jail terms and fines!

Today’s Lecture:

• We found out about several types of computer crimes that occur over cyber space
• We familiarized ourselves with with several methods that can be used to minimize the ill effects of
these crimes

Next Lecture’ Goals

(Social Implications of Computing)

We will explore the impact of computing on:

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