Computer Security

1
Computer Security

• Std XI Chapter 8

2
Security Principles
During
Data Transmission on the Internet
3
Confidentiality

• Content of the message should be accessed by
• Sender
• Recipient

4
Integrity

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

5
Authentication

• Receiver must be sure of the senders identity
• All users must have a
• user ID
• password

6
Nonrepudiation

• A sender must not deny having sent the message to
  the receiver

7
For security

• Encryption and Decryption are used.

8
Destructive software

• Viruses
• Malware
• Spyware
• Worms
• Browser Hijackers
• Spam

9
Viruses

• Vital Information Resources Under Seize

10
Viruses
Attacks software such as O.S. application
software e-mails 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 users permission
• Spyware gathers information
• relays info to advertisers others
• installed w/o consent, knowledge (click,
  pop-up) (adware)

14
Replicate yourself
Eat up Computers 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 e-mail addresses from chatrooms,
  websites, customer lists, newsgroups, and viruses
  which harvest users' address books,

18
Antivirus

• 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. Solomons
• 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