Download Part 1

Protecting Your Computer
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Internet Annoyances (Already done in
Chapter 3)
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Spam
Pop-ups
Identity theft
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phishing
hoaxes
Spyware
1
Computer Threats
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Cyber-crimes are
criminal acts
conducted through the
use of computers by
Cyber-criminals.
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Hacker: Anyone who
unlawfully accesses a
computer system
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What Hackers Do
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Steal information from computers:
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Credit card numbers
Bank account numbers
Internet packet sniffing
Commit identity theft
3
Denial of Service Attacks
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Web servers are sent millions of bogus
requests
Overloads the system
Consequently they shut down
Service is denied legitimate users
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Denial of Service Attacks
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Distributed denial of
service attacks use
many computers
Backdoor programs
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Trojan horse
Zombies
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How Hackers Gain Access
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Direct access:
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Hacking software
Indirect access:
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Internet connection
Logical ports
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Computer Safeguards: Firewalls
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Software programs or
hardware devices designed
to close logical ports to
invaders
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A firewall is built into Windows
XP
More robust firewalls are
available from other vendors.
Firewalls are critical if you
have an always-on broadband
connection.
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Firewall
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Always on Internet service is a problem
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use a router or firewall software
see IT website for Firewall information
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Firewall
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Objective: to keep the internal network secure
from the outside
It is a hardware device or software through which
all traffic must pass
Firewall
LAN
WAN
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Router
Does dynamic address translation
ISP
Firewall
IP address
LAN
111.22.3.44
WAN
IP addresses
known only to
the router, not
to the ISP
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Protecting a Wireless Network
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Wireless network range doesn’t stop at the
property line.
Default device and network ID settings allow
intruders to enter the network.
Internet bandwidth can be stolen
Computers can be vulnerable to hacker intrusion
and takeover.
11
Secure Your Wireless Router
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Change Your Network Name (SSID)
Disable SSID Broadcast
Change the Default Password on Your Router
Turn on Encryption (WAP is best)
Implement Media Access Control
Apply Firmware Upgrades
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Change Your Network Name
Disable SSID Broadcast
Turn on Encryption
Change the Default Password
Implement Media Access Control
13
Software Sabotage
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Risks
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Virus
Worm
Trojan horse
Spyware
DOS Attacks
Protection
14
Computer Threat - Viruses
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A virus is a program that attaches itself to
another program
It hides within the code of the host program
When host program executes the virus
code executes also and copies itself to
other programs
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What Viruses Do
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Replicate themselves:
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Slow down networks
Secondary objectives:
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Annoying messages
Delete files on the hard drive
Change computer settings
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How Does a Computer
Catch a Virus
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Virus
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Macro virus
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Attach to documents
Email virus
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Attachments
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Antivirus Software
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Programs designed to detect viruses:
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Scan files looking for virus signatures (unique code)
Provides options for deleting or fixing infected files
Detect known viruses
Antivirus programs need to be updated frequently
20
Use Anti-virus Software
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Install and update anti-virus software
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UofC IT anti-virus web page
Free software: McAffee
ISP might provide free
Otherwise buy it (McAffee, Norton, …)
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Email Virus Detection
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ISP mail server (UofC IT and CPSC)
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Scans incoming and outgoing messages, notifies user if
finds virus (strips attachments), and quarantines the
message
User can recover message from quarantine
If you suspect: don’t open the attachment
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Delete the message
Scan in email program or save to disk and then scan with
virus detection software
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Sober
Source: Calgary Herald
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Email Virus Detection
My email
From: [email protected]
Subject: WARNING - VIRUS (Worm.Sober.U) IN MAIL TO
YOU
Date: November 25, 2005 10:20:55 AM MST (CA)
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*** VIRUS ALERT ***
Dear user,
This is an automatically generated message from the University of
Calgary, Department of Computer Science (CPSC).
The CPSC email system has detected a piece of email with a virus called:
Worm.Sober.U
in an email addressed to you from:
<[email protected]>
The Subject of this email was:
Mail delivery failed
Delivery of the original email has been stopped. A copy of the message has
been placed under quarantine.
Please visit the CPSC Maia Mailguard system located:
http://imgw1.cpsc.ucalgary.ca/mail
to view your quarantined messages. You will be required to log into
this system using your CPSC Email address and your CPSC Login Password.
For your reference, here are some selected headers from the email:
-----------------------------------------------------------------Date: Fri, 25 Nov 2005 10:20:55 -0700 (MST)
From: [email protected] (Empty if virus is known to forge sender address)
To:
Subject: Mail delivery failed
Received: dpwtlcd.com (S010600112f1f983b.cg.shawcable.net [68.147.104.66])
25
Worm
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Program that travels independently over
computer networks, seeking uninfected
sites
Replicates and starts up thousands of
processes
Overloads a system
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The Cost of Worms
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Nimba, Sept. 18, 2001
In 24 h infected 2.2 million computers
Microsoft Windows
Huge traffic disabled web and email
servers
Damaged system files
27
Trojan Horse
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Program that performs a useful task while
also being secretly destructive
A logic bomb responds to a particular event
Cannot replicate
E.G. Logon Trojan horse
28
Denial of Service Attacks
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Web servers are sent millions of bogus
requests
Overloads the system
Consequently they shut down
Service is denied legitimate users
29
Protection from Viruses and
Security Risks
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Use anti-virus software
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Update frequently
Use anti-spyware software
Update your operating system
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Automatic updates and security patches
Microsoft
Macintosh
30
Computer Security: Reducing Risks
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Disaster Planning
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backup power
monitoring, alarms
backup of data
redundant sites or hot sites
31
Computer Security: Reducing Risks
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Physical Access Restrictions
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something
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you have: key, ID card
you know: password, personal information
you do: signature, …
About you: Biometrics
32
Passwords
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The most common tool for restricting
access to computer systems
Weakness
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user
sustained guessing
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program guesses words from online dictionaries
33
Password Guidelines
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Don’t use
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real words
names
plurals
common expressions
reversal
34
Passwords
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Do
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mix letters and numbers
change frequently
keep secret
35
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Biometrics
36