Computer Security Std XI– Chapter 8

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

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

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

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

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

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

Destructive software Viruses Malware Spyware Worms Browser Hijackers Spam

Vital Information Resources Under Seize Viruses Vital Information Resources Under Seize

Viruses Cannot affect hardware Attacks software such as O.S. application software e-mails data Cannot affect hardware

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

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

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)

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

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

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

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,

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

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

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!

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

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

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

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

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

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