A Basic Introduction to Computer Security John H. Porter University of Virginia Department of Environmental Sciences

Achieving Absolute Computer Security n There is only one method that can assure absolute security for the data and programs on your computer n Unplug it from the power outlet!!!

The Bad Guys n Trojan Horses Software that does other things than it says it does – often maliciousSoftware that does other things than it says it does – often malicious n Worms Attempt to circumvent controls on network accessAttempt to circumvent controls on network access n Viruses Attempt to modify programs on your computer to add malicious codeAttempt to modify programs on your computer to add malicious code

The Bad Guys n Sniffers Tap network lines to capture data and passwordsTap network lines to capture data and passwords n Thieves Stolen computersStolen computers n Bad Luck Floods, fire, lightning, power surgesFloods, fire, lightning, power surges

Achieving Relative Security n Backups n Boundary Defense n Defense on the homefront

Backups n All computers will, at some point, experience a security breach Backups let you recover lost dataBackups let you recover lost data n Off-site backups protects you against data loss due to violations of physical security Try getting your data back off a stolen or burned hard drive!Try getting your data back off a stolen or burned hard drive!

Boundary Defense n Boundary defenses focus on keeping malicious users or programs from having access to files on your computer PasswordsPasswords Control of Internet PortsControl of Internet Ports Restricting ways files may be stored on your computerRestricting ways files may be stored on your computer

Passwords n Not all passwords are created equal – some are easier to crack Ones based on publically available information about you (e.g., your name)Ones based on publically available information about you (e.g., your name) Passwords based on dictionary rulesPasswords based on dictionary rules Passwords that are too short or use repeating charactersPasswords that are too short or use repeating characters

Strong Passwords n One easy way to create strong passwords is to take the first letter off each word in a sentence and add some punctuation E.g., Iwtbot, - “It was the best of times,”E.g., Iwtbot, - “It was the best of times,” 2b,ON2b – “To Be, or Not to be”2b,ON2b – “To Be, or Not to be” n Also, varying capitalization can help JHwaPDM!JHwaPDM!

Protecting Passwords n Even the most “secure” password is vulnerable if communication lines are compromised E.g., “sniffers”E.g., “sniffers” n Use of encrypted connections (ssl, https) can eliminate or greatly reduce this risk

Know What You are Sharing n Your computer provides a number of Internet Ports You want to eliminate access to ports that are not serving a legitimate purposeYou want to eliminate access to ports that are not serving a legitimate purpose n You can test at sites like ShieldsUp: Not all access is bad, but you want to KNOW what is exposed!

Limit the Places that can Access your Computer n Most SQL databases support restricting access to particular network domains, or even individual machines If your web and database servers are on the same host, you may be able to eliminate ALL network access to the database, since all interactions are mediated by your web serverIf your web and database servers are on the same host, you may be able to eliminate ALL network access to the database, since all interactions are mediated by your web server

Keep your Eyes Open! n Just as you would not walk down a darkened alley without paying attention to your surroundings, you need to be alert to strange computer behaviors that may indicate a security problem n Check your software support pages frequently for news about vulnerabilities and fixes

Defense on the Homefront n Limit access of your computer to trusted individuals Usually not too much trouble at field stationsUsually not too much trouble at field stations Is especially an issue for web pages that contain DBMS login information in free textIs especially an issue for web pages that contain DBMS login information in free text n Get a good virus checker and update it frequently (daily if possible, at least weekly)

Defense on the Homefront n Keep updates to Windows current As security holes are detected, fixes will become availableAs security holes are detected, fixes will become available Windows provides for automatic updatesWindows provides for automatic updates Recent worms (e.g., Blaster) utilized a flaw in the RPC module of Windows to infect large numbers of otherwise protected computers before a fix was availableRecent worms (e.g., Blaster) utilized a flaw in the RPC module of Windows to infect large numbers of otherwise protected computers before a fix was available

Protecting the Homefront n Monitor your logs to detect attempts to attack your system Window’s Events logsWindow’s Events logs Web server logsWeb server logs n Exercise good judgment on downloading files Every file downloaded is a potential security intrusionEvery file downloaded is a potential security intrusion

Security is Relative n Security is always relative, but it is possible to create a reasonable level of security n The more obscure a resource is, either because it uses “unusual” software or is inconspicuous on the web, the less likely someone is to try to break into it

Useful Places to Look n - Computer Emergency Response Team n - home of ShieldsUp and others n - Symantec anti- virus site n curity_internet/index.html - a general guide to Internet Security issues curity_internet/index.html curity_internet/index.html