Computer Security

1. Computer Security

2. Data Availability • Data in memory is volatile. • Data in storage is non-volatile so it is always available • As long as it isn’t trashed accidentally or deliberately. • So, when using software (Word, etc.) save often.

3. Data Availability • BACK UP IMPORTANT DATA • Often • Specifically what should YOU do with your data. • At least once per semester, back up your entire computer if it is at all convenient. • I use a removable hard disk • They are currently cheap

4. Data Availability • I back up my “My Documents” folder on a monthly basis, usually burning it to a CD. • My Really important stuff such as this semester’s notes, tests, grades, etc I back up on a weekly basis to two places – another drive on my home network AND a USB flash memory drive • My really, really, really important stuff such as my financial data, I back up every time I use it to a USB flash drive and monthly to a CD.

5. Data Security • Secure data is data that is difficult for OTHERS to access. • There are two basic methods of securing data: • Password systems • Encryption

6. Password Systems • Username and Password – Good systems will not tell you which one is wrong if one of them is. • Usernames are often given to you so you have no choice as to what to use. • Most people choose their own passwords.

7. Password Systems (Cont) • Bad things users do: • Easy to guess passwords. • Tell their passwords to friends. • Write their passwords on a paper and leave it near their computer. • Short passwords can be guessed by brute force.

8. Password Systems (Cont) • If the system is not secured, then the password file may be compromised and all passwords will be unsecured. • Some systems (older versions of Windows) had their password files unencrypted. • The system manager has special powers over users, so if a system manager’s account can be cracked all security is lost.

9. Choosing Passwords • Make it long. • Use both letters and digits, maybe even special symbols • Use upper and lower case. • Example: dsitBtitw5 (dr sidbury is the best teacher in the world 5) • Example: P=2*(L+w)

10. Cryptography/Encryption • Ebubjtfodpefetpuibujuepfto’umpplopsnbm. • Data is encoded so that it doesn’t look normal.

11. What else can go wrong internally? • Programs may make duplicate copies of data which aren’t secure and may even be sent to developers. • Erased data is not really erased, unless you take special precautions.

12. What are viruses? • Unwanted and unanticipated programs • May damage a computer or degrade its performance • Viruses may appear: • As an email attachment • In another program • In user data files (MS Word Macros) • On disk in a place that is routinely activated. • A virus cannot be spread without a human action • Worms • Similar to viruses • Have capability to travel without any human action • e.g., send a copy of itself to everyone in your email address book, then send to everyone in the receiver’s addr book

13. How to detect viruses? • Anti-virus programs compare each file against known viruses • A computer may be set up in such a way that no disk files can be accessed until virus scanning has been completed. • A new virus may not be known by the anti-virus program until the virus information is available to the anti-virus program • Be proactive in getting information of new viruses for the anti-virus program

14. How to protect yourself? • Be sure anti-virus software is running on your computer and keep the virus info up to date • Do not execute (open) any program (file) downloaded from the Internet without first having it scanned for viruses. • Be cautious before allowing your Web browser to run programs behind the scenes • Save all your email attachments to hard disk and scan them for viruses before open them • Do not run any macro in Word documents or Excel spreadsheets unless you know they are reliable • Install and configure firewalls if your computer is connected to the Web.

15. Spyware • Keyboard Sniffers • Wire tapping • Trojan Horses • Packet Sniffer

16. Firewalls • A firewall controls/monitors traffic from one system to another one. • The systems may be individual computers or networks. • A firewall can block unauthorized access to your computer while permitting authorized communications • Most computers which you buy have a built in firewall. You should configure them or you will not be able to use software correctly.

17. Protect your PC • Install a firewall to restrict ports that can be used for Internet communications to your computer • Require users of computer to have an account and password. • Use anti-virus software to check all incoming materials (through email, ftp, webpages) for virus and spyware. • Carefully monitor new programs, games and other files you bring into your system. Some programs may be vulnerable to security breaches. • If the operating system supports file permissions, keep your private files accessible to you only.

18. Does keeping a computer online comprise its security? • Operating systems and other programs are quite complex, and thus prone to containing errors that in turn could create vulnerability. • Software vendors monitor their products and release updates to resolve security risks and other errors. • Thus, make sure install those updates on your computer. • Configure your Windows XP to download updates from Microsoft and install them on a regularly basis. • Use password, encryption, etc to protect your wireless network from unauthorized access.

19. Summary • Data should be safe (not likely to be lost) and secure (hard for someone else to get) • Safety is primarily implemented with backups • Security is implemented with: • Username/Password systems • Cryptography – Encryption/Decryption • Antivirus • Spyware • Firewalls