1. Computer Security
Std XI– Chapter 8

2. Data Transmission on the Internet
Security Principles
During
Data Transmission on the Internet

3. Confidentiality Content of the message should be accessed by Sender &
Recipient

4. Message/data must arrive exactly as it was sent
Integrity
Message/data must arrive exactly as it was sent
NO modification done either
accidentally or
maliciously

5. Receiver must be sure of the sender’s identity
Authentication
Receiver must be sure of the sender’s identity
All users must have a
user ID &
password

6. A sender must not deny having sent the message to the receiver
Nonrepudiation
A sender must not deny having sent the message to the receiver

7. Encryption and Decryption are used.
For security
Encryption and Decryption are used.

8. Destructive software Viruses Malware Spyware Worms Browser Hijackers
Spam

9. Vital Information Resources Under Seize
Viruses
Vital Information Resources Under Seize

10. Viruses Cannot affect hardware
Attacks software such as O.S. application software s data
Cannot affect hardware

11. Types of Viruses Boot sector virus Macro virus E-mail virus
File infector virus (.com, .exe, .sys, .ovl, .prg, .mnu)

12. How the virus works Clean uninfected program Virus Infected program
Compute A , B
Delete all files
Corrupt data
Send copy of virus to all programs
Perform printing
End
Compute A , B
Perform printing
End

13. Malware & Spyware performs malicious action w/o user’s permission
Spyware gathers information
relays info to advertisers & others
installed w/o consent, knowledge (click, pop-up) (adware)

14. Eat up Computer’s resources
Replicate yourself
Eat up Computer’s resources
Worms
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Replicate yourself
Make the computer unusable
…………
No destruction

15. Trojan Horse Is not self replicating
main purpose is not make modifications in the target computer
Requires interaction with the hacker
Reveals confidential info (user ID, pwd)
Allows hackers remote access to target system

16. Browser Hijackers alters your browser settings
redirects home page to rogue search engines
With sponsored links as results (hit list)
Could also direct the browser to an error page
Forces hits

17. Spam abuse of e-mail unsolicited mail, bulk e-mail (UBE)
Commercial content
Use of spam guard
Spammers collect addresses from chatrooms, websites, customer lists, newsgroups, and viruses which harvest users' address books,

18. Antivirus can be purchased or downloaded
protection from virus, worm, trojan horse, malware
can be purchased or downloaded

19. Commercial Antivirus software
AVG
BitDefender
Norton
McAfee
Kaspersky
eScan K7
Bull Guard
Dr.Web
Panda Security
PC Tools
Protector Plus
Rising
ZoneAlarm

20. Freely available Antivirus software
AOL Active Virus Shield
AVG Antivirus Free Avast Home
Bitdefender 8 free edition
Comodo
McAfee VirusScan Plus
PC Tools AntiVirus Free Edition
Dr.Web Cureit!

21. Antivirus software downloads
Clam
ClamWin
Moon Secure
Open
Winpooch
Abandonware
Aidstest
Antiviral Toolkit Pro
Central Point
dLight
Dr. Solomon’s
The Antidote
Thunderbyte
Turbo

22. Preventive Measures Do not open e-mail attachments
Update anti-virus software regularly
Delete chain letters, forward, virus alerts and junk mail
When Downloading files if unsure of their authenticity, scan them first
Backup regularly
Do not hide file extensions

23. Preventive Measures Do not download files from strangers
If you have to then download to a removable disk and scan with antivirus
Protect using Internet firewall

24. To Turn on Firewall Click start Control Panel Security Center
Windows firewall

25. For Unhiding File Extensions
Click My Computer
Tools Menu
Folder Options
View tab
Uncheck “Hide extensions for known file types”

26. Lab Exercise Find names of Trojan Horses Find names of Viruses
Find names of Worms
Find details of Malware
Find details of spyware
Find names of Browser Hijackers
Anti Virus scanning procedure details