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The Building Blocks of Safe Computing


These building blocks describe eighteen actions that, if taken, can help reduce the risk to your computers, mobile devices, removable storage media, and the data they hold.

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(Click each building block below to display/hide detailed information)

Use strong, difficult-to-guess passwords on computers, mobile devices and other password protected media

  • Anyone who knows or can guess your password can see or do whatever you can.
  • Passwords should be at least 8 characters, and a mix of letters, numbers and symbols. 
  • Avoid dictionary words in any language, obvious sequences (e.g., 123qwerty, abcd1234) and simple alterations of common words (e.g., p@ssw0rd).
  • Never set a blank password or use a default or initial value password.
  • Use different ID and password combinations for different web sites.
  • Phrases can be the basis for an effective and easy to remember password, e.g., “I am one happy person at Princeton University!” could become the password “Im1hp@PU!” (Please do not use this password or any other password shared as an example in a public document.)
  • Do not share passwords.
  • Change your password regularly to limit the time a hacker has to discover it.
  • Avoid writing passwords down, but if you must, mask it, keep the piece of paper in a safe place and do not include related data (e.g., ID, site name).
  • Commercially available password management software can keep your passwords in an encrypted, password-protected file.  Some products can save the file in the “cloud” allowing users to share passwords among multiple computing and mobile devices. Check with your IT support person or the OIT Help Desk at (609) 258-HELP to ensure the product provides appropriate security controls.

Ensure that vendor software updates are applied to your systems promptly

  • When vendors release software updates, hackers can determine how to break into systems that have not been updated.
  • Hackers then probe systems on the Internet looking for non-updated computers to attack.
  • Your system’s software and application programs should be configured to apply or notify you of automatic updates when available.

Confirm that up-to-date, anti-virus software is running on your systems

  • Hundreds of new viruses are developed each day.
  • Anti-virus software can only detect and react to known viruses.
  • Your anti-virus software should be configured to automatically apply updates as frequently as possible, at least daily.
  • If you purchase your own anti-virus software for your personal system, remember to renew your subscription before it expires so that you continue to receive updates.

Limit other systems’ ability to access your computer with configuration settings, a firewall and other tools

  • Configure wireless routers to only allow connections by authorized devices, e.g., require a key, password or registered MAC address.
  • Restrict network access to your system, especially on a public or home network, i.e., set up your system to not be discoverable, not share network folders and not accept remote desktop connections.
  • Windows, Mac, Linux and other systems have built-in firewall software that can stop computers from probing your system, and can block your computer, if infected, from attacking other systems.
  • A hardware firewall adds security by physically segregating the firewall functions from the system it is protecting.
  • Ensure the firewall you use is activated and configured to block unexpected network connections (in or out).
  • Adding a host intrusion prevention product can provide additional protection by blocking known attack patterns that it finds in the network traffic entering or exiting your system.

Avoid doing every day work using an account with administrative privileges

  • Set up your day-to-day account with user-level privileges. 
  • If you inadvertently open a virus-infected application or link, it will only be able to perform functions on your system that your logged-in ID can perform.  
  • Since user-level accounts typically cannot install software, viruses cannot be installed and executed on your system without your entering the administrator ID and password. 
  • A second administrator level account can be used when you need to install software or to perform system administrative tasks.

Lock any computer or mobile device when it is left unattended

  • Anyone who can access your logged-in system can do whatever you can do on your system without having to learn your password.
  • Timeout-based locks, i.e., locking the computer after a defined period of inactivity give an intruder too much time for mischief.
  • Manually locking your computer or mobile device prevents passersby from using your logged in session.
  • Avoid setting your system to automatically log into e-mail and other applications that may hold personal data.

Know the sensitivity of the data on your computers, mobile devices and storage media

  •  Information is considered sensitive if its exposure to unauthorized individuals would cause financial or reputational loss, including information that:
    • Can result in identity theft, such as social security numbers, account numbers, driver’s license numbers, birth dates, passwords, etc. 
    • Is protected by law or contract, or would pose any other risk to the University, if exposed. 
  • Without understanding the sensitivity of the information held on your computer, mobile device or storage medium, you may inadvertently make sensitive information available to unauthorized individuals.

Actively control access to sensitive data

  • Make sure that, for any files and folders containing sensitive data, you indicate who specifically can access those files and folders and what they can do (e.g., read only, update, delete)
  • Beware of attempts to gain your confidence, and access to data, by individuals using “social engineering” techniques.
  • Always ensure that individuals to whom you give information are properly authorized.
  • Restrict what you share on social media sites.  It could be used to steal your identity, be viewed by a prospective employer, etc.

Ensure that your computers and mobile devices encrypt sensitive information when transmitting it over a network

  • Unencrypted, sensitive data can be viewed when it travels across the Internet or is transmitted over an unsecured wireless network.
  • Virtual Private Network (VPN) technology improves security by encrypting all data passing between your computer or mobile device and the organization providing the VPN service.
  • When you send sensitive information to a web application, look for the lock icon on your browser.  It tells you that the traffic is encrypted.
  • Be careful when your browser shows that the identity of the target web site cannot be verified.  It may be a counterfeit site.

Encrypt sensitive data on computers, mobile devices and storage media

  • If you store sensitive information on your computer, mobile device or storage medium, encryption reduce the risk of that information being exposed if the device is lost or stolen.
  • Ask your IT support person or the OIT Help Desk at (609) 258-HELP for recommended products.

Avoid using e-mail to exchange or store sensitive information

  • Messages originating from senders or destined for recipients outside of the University’s e-mail system, travel across networks and are stored on e-mail systems managed by other organizations.
  • While the University is committed to following IT security best practices for managing e-mail, we cannot be certain that the same holds true for e-mail and network providers outside of the University.   So, you should assume that any e-mail message sent to or received from an off-campus address is at risk.
  • If you must send or receive sensitive information via e-mail, ask your IT support person or the OIT Help Desk at (609) 258-HELP for alternatives.

Do not install any piece of computer software or mobile “app” until you have confirmed its security is effective

  • Check with your IT support person or the OIT Help Desk at (609) 258-HELP to determine if the software has been approved for University use.
  • If the University has not reviewed the product, check the reviews published by well-known, respected product review organizations, such as C|NET, PC World, Mac World, etc.

Protect your web browsing cookies

  • “Cookies” are small files that web sites send to your browser to facilitate your interaction with the site. If you’ve entered sensitive data into a web site, it may be held in a cookie, but how well protected the cookies are is up to the web site.
  • To ensure that one site does not obtain sensitive data by reading another site’s cookies, set up your browser to delete all cookies when you exit, and make sure that, when you exchange sensitive information with a web site, you close all browser windows before accessing another site.

Use discretion when surfing the Web

  • Avoid web sites of organizations or individuals of an unknown or questionable reputation.  
  • Shun web sites that have a history of spreading malicious software, such as pop culture sites.
  • Before clicking a link, view the web site’s address by passing the cursor over the link (but not clicking).  The web site address that displays should point to a site name that you expect.

Be discerning when clicking links or attachments

  • E-mail messages can be made to look like they are from someone you know.
  • Before clicking attachments or links, be reasonably certain of the source, expect the attachment and know what the attachment contains. 
  • Ask yourself, “Is this a note that my friend would send?” “Was I expecting anything like this?”

Beware of the phishing threat

  • Phishing is a scam that tricks you into providing passwords, social security numbers, bank account and credit card numbers, or other personal information while pretending to be from a legitimate institution.  
  • Reputable organizations do not ask that you provide personal information in an e-mail reply.  
  • If you receive a suspect message appearing to be from Princeton, contact the OIT Help Desk at (609) 258-HELP.

Be suspicious of unsolicited Web messages, warnings, popups and free services

  • Responding to unsolicited messages, warnings and popups you receive while web browsing, especially ones promising free services, such as “We’ve detected a virus on your system!!” and “Click here for faster Internet!” may download malicious software onto your system or expose your Web traffic to unauthorized individuals, even if it is encrypted.
  • Avoid clicking anything on a popup window.
  • Close popups using your browser menu or system task bar.

Wipe your computers, mobile devices and storage media before discarding, donating or repurposing them

  • Deleting a file does not actually erase it. Systems delete files by marking the storage space the file occupies for reuse.  Until that space is reused, the data is still there. 
  • Disk shredding software erases individual files on demand.
  • Disk wiping software completely erases a storage medium.

NOTE - If a University computer, mobile device or storage medium is lost, stolen or compromised, or you suspect that sensitive University information has been exposed, please contact the OIT Help Desk immediately at (609) 258-HELP.  Consultants are available to help you 24 hours a day, seven days a week.