Fact Sheet 36:
Securing Your Computer to Maintain Your Privacy

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Copyright © 2012-2016
Privacy Rights Clearinghouse
Posted April 2012
Revised July 2016

1. Introduction
2. Choosing Your Operating System
3. Choosing Your Internet Browser and Software
4. Using Firewalls, Anti-virus Programs, and Anti-malware Programs

5. Tips for Using Your Computer Safely

6. Using Wireless Connections (Wi-Fi)
7. Resources

1. Introduction

Please note that the mention of any specific products does not constitute an endorsement by PRC.   

Maintaining the security of your computer can be challenging task. Hackers often seem to be one step ahead of computer users, even those who are following the best security practices.  However, securing your computer is essential to protecting your privacy, reducing the risk of identity theft, and preventing hackers from taking over your computer.

The best computer security practices require you to take a multi-pronged approach. They involve protecting your sensitive information by preventing, detecting, and responding to a wide variety of attacks.

2. Choosing Your Operating System

Your computer's operating system is the main program on your computer. It performs a variety of functions, including determining what types of software you can install, coordinating the applications running on the computer at any given time, and allowing your software applications (web browsers, word processors, and email clients) to operate.  When you buy a computer, you are usually also choosing a specific operating system.

Manufacturers typically ship computers with a particular operating system. Most PCs ship with the latest version of the Windows operating system. The current Windows operating system is Windows 10.  Apple computers use the Mac OS X.

Windows operating systems traditionally have been targeted with malware more often than other operating systems. This may be due to the larger base of Windows installations, which makes it a more attractive target. However, Apple's Mac OS X is definitely not immune to security flaws. In fact, as more consumers purchase Apple products, malware makers have begun to target Mac OS X.

Some computer security professionals consider Linux and other lesser known operating systems to be the most secure, primarily because they tend not to be targeted. For those interested in trying out the Linux operating system, many recommend Ubuntu, a free, open-source Linux distribution. 

No matter which operating system you use, it's important that you update it regularly. Windows operating systems are typically updated at least monthly, typically on so-called "Patch Tuesday." Other operating systems may not be updated quite as frequently or on a regular schedule. It's best to set your operating system to update automatically. The method for doing so will vary depending upon your particular operating system.

If your computer uses Windows XP as the operating system, it's very important to be aware that Microsoft support for Windows XP ended on April 8, 2014.  This means that you no longer receive software updates from Windows Update, including security updates that can help protect your computer from harmful viruses and malware. 

3. Choosing Your Internet Browser and Software

In the past, computer security experts regarded operating systems as the “Achilles’ heel” of computer security. More recently, experts have come to regard commonly installed software programs as the greater threat to security.

It's always important to thoroughly investigate any software that you may download to your computer.  Any software potentially may contain malware. However, even software that is not malicious can expose your computer to security vulnerabilities. 

Your internet browser. Many people regard the Mozilla Firefox browser as superior to Microsoft’s Internet Explorer.  Mozilla tends to patch Firefox security vulnerabilities more quickly than Microsoft patches Explorer. One advantage of Firefox is that it is an “open source” program. This allows security professionals to become involved in fixing bugs and building stronger security features. Another advantage of Firefox is its so-called Add-Ons, which can be used to strengthen Firefox’s built-in security and privacy features. Three Firefox Add-Ons that we recommend are NoScript, Better Privacy, and HTTPS Everywhere.

NoScript. When you install NoScript, executable contents or "scripts" such as JavaScript, Java, Flash, Silverlight and others, are blocked by default. You can allow these scripts to run on a site that you trust (for example, your bank) through a simple mouse click. You can "whitelist" or authorize scripts for a particular session or permanently if you trust a website.

NoScript helps protect against so-called “drive-by downloads” where simply visiting a particular website can cause malware to be downloaded and executed on your computer. Criminals can use programming flaws in browsers to get malware onto your computer via a “drive-by download” without you ever noticing. For example, this can occur when visiting a legitimate site that happens to unwittingly host an advertisement containing malware.

Better Privacy. Many websites have begun to utilize a type of cookie called a "flash cookie" (sometimes known as a "supercookie") that is more persistent than a regular cookie. Normal procedures for erasing standard cookies, clearing history, erasing the cache, or choosing a "delete private data" option within the browser will not affect flash cookies. Flash cookies thus may persist despite user efforts to delete all cookies. The Firefox Add-On Better Privacy can assist in deleting flash cookies.

HTTPS Everywhere. HTTPS Everywhere encrypts connections to over 1,000 popular websites. Without HTTPS, your online activities are vulnerable to eavesdropping and your accounts are vulnerable to hijacking. HTTPS Everywhere makes it easier for you to keep your user names, passwords, and browsing histories private.

It’s important to note that HTTPS Everywhere can protect you only when you're using sites that support HTTPS and for which HTTPS Everywhere includes rules.  HTTPS Everywhere depends entirely on the security features of the individual websites that you use. It activates those security features, but it can't create them if they don't already exist. If you use a site not supported by HTTPS Everywhere or a site that provides some information in an insecure way, HTTPS Everywhere can't provide additional protection for your use of that site.

No matter which browser you use, it's important that you update it as newer versions come out which address security vulnerabilities. The Firefox browser will automatically deliver updates on a fairly frequent schedule, typically every few weeks. Other browsers may not update as frequently and may not update automatically.

The U.S. Computer Emergency Readiness Team (US-CERT) has prepared an extensive “How-To” guide for securing your browser. Detailed instructions and screen shots are provided for the Internet Explorer, Mozilla Firefox, and Apple Safari browsers.  

Your portable document reader. Most people use Adobe Reader to read and print portable documents (.pdf files), such as forms and publications. Like Internet Explorer, the Adobe Reader is extremely popular, so it has become a target for the bad guys. Adobe tends to be slow in patching security vulnerabilities. Many security experts believe that you are safer using alternative document readers. 

Adobe Flash Player. Most computer users have Adobe’s Flash Player installed. In many cases, users are running an older version of Flash Player that may contain numerous security vulnerabilities. Be sure that you set your Flash Player to update automatically.

Java. If your computer has Java installed, the Department of Homeland Security has recommended that you disable it.  It's unlikely that a typical computer user will ever need to use Java.  Java has been responsible for a large number of malware attacks on the computers of unsuspecting users.  You can disable Java easily.

Be cautious when downloading software.  Unwanted software may infect your computer if you don't take care when downloading a new program.  Be sure to obtain software from legitimate sources and watch for "bundling" of additional unwanted programs with legitimate software. 

4. Using Firewalls, Anti-virus Programs, and Anti-malware Programs

Every user of a personal computer should be familiar with firewalls, anti-virus programs, and anti-malware programs. These programs complement one another and must be used together to provide the highest level of protection to your computer. They are necessary to protect you from threats designed to damage, disrupt, or inflict illegitimate activity on your computer.

The term malware is short for malicious software.  The more common types of malware include viruses, worms, Trojans, spyware, and adware. The damage inflicted by malware may range from minor annoyances to more serious problems including stealing confidential information, destroying data, and disabling your computer.

It’s not really necessary for you to understand the technical differences between these threats. There are literally dozens of different varieties.  

Most security software that comes pre-installed on a computer only works for a short time unless you pay a subscription fee to keep it in effect. In any case, security software only protects you against the newest threats if it is kept up-to-date. That's why it is critical to set your security software to update automatically.

Firewalls, anti-virus programs, and anti-malware programs are important elements to protecting your information. However, none of these is guaranteed to protect you from an attack. Combining these technologies with good security habits is the best way to reduce your risk. Some anti-virus programs also contain anti-malware capability. However, given the increasing sophistication of malware programs, it’s best to use two different anti-malware programs in addition to an anti-virus program. Each one looks for slightly different sets of threats, and used together they may offer increased security.

According to a Consumer Reports (CR) article, free programs should adequately protect most computer users from malware. Consider paying for software mostly for convenience and some extra features. The best free package in CR's security software ratings was Avast! Free Antivirus. 

Firewalls. A firewall helps to prevent data from entering or leaving your computer without your permission. It helps make you invisible on the internet and blocks communications from unauthorized sources.

Every computer that is connected to the internet should run a firewall at all times. There are two types of firewalls—software and hardware. You can run both simultaneously. In fact, it is a good idea to use both a software and hardware firewall. But never run two software firewalls simultaneously.

Some operating systems have built-in software firewalls. An example of a software firewall is the one built into most Windows operating systems.  You should leave the Windows firewall turned on unless you replace it with third-party firewall software.  Other software firewalls are supplied by outside vendors, or may be part of a commercial security suite. A software firewall must be properly configured in order to be effective.  

Hardware firewalls can be purchased as stand-alone products or may be found in broadband routers having firewall features. A router sits between your modem and your computer or your network. It is hard to hack your computer or a network when it is hidden behind a hardware firewall box. However, it is important to properly configure your router, particularly by changing the default password to one that is difficult to crack. To ensure that your hardware firewall is properly configured, consult the product documentation.

Anti-virus programs. A virus is simply a computer program. It can do anything that any other program you run on your computer can do. A computer virus is a program that spreads by first infecting files or the system areas of a computer and then making copies of itself. While some viruses are harmless, others may damage data files, some may destroy files, and others may just spread to other computers.

Detailed reviews of anti-virus software are available from AV Comparatives, an independent anti-virus software testing organization. 

You should not have two anti-virus programs actively running on your computer at the same time. Running more than one anti-virus program at the same time can potentially cause conflicts that affect your computer's performance. Be sure to fully disable or remove any anti-virus programs that you are no longer using.

Anti-malware programs. Malware is a broad category of computer threats including spyware and other unwanted programs that may be installed without your knowledge or consent. Spyware can secretly gather your information through your Internet connection without your knowledge. Once spyware is installed, it may deploy numerous files onto your system. Some of these files are so well hidden that they are difficult to find and remove.

Spyware programs may be included with other software you want. When you consent to download a program, such as a music sharing program, you may also be consenting to download spyware. You might not be aware that you agreed to the spyware installation because your consent is buried in an end-user-license agreement (EULA).

Be cautious about clicking on pop-up boxes. Spyware programs may create a pop-up box where you can click “yes” or “no” to a particular question. If you click on either choice your browser may be tricked into thinking you initiated a download of spyware.

Anti-malware programs can help to eliminate many of these threats. Security experts recommend that you use at least two anti-malware programs on your computer, as no one program has been found to be fully effective at detecting and removing these threats.  

5. Tips for Using Your Computer Safely

Keep your software up-to-date. Computer hackers are always finding new ways to penetrate the defenses of your software programs. Software vendors respond with patches that close newly found security holes. To stay protected, you need to download and install patches for both your operating system and your software applications whenever they become available. Software patches or updates often address a problem or vulnerability within a program.

Sometimes, vendors will release an upgraded version of their software, although they may refer to the upgrade as a patch. It is important to install a patch as soon as possible to protect your computer from attackers who would take advantage of the vulnerability. Attackers may target vulnerabilities for months or even years after patches are available.

Keeping your software programs up to date can be a daunting task, since most computers contain dozens of software programs. Many are pre-installed when you buy your computer.  Hackers are constantly attacking flaws in popular software products such as Adobe PDF Reader, Adobe Flash Player, QuickTime, and Java.  Some software will automatically check for updates. If automatic updates are not available, check your software vendors' websites periodically for updates.

Use strong passwords. Whenever you have an opportunity to create and use a password to protect your information, make sure that you use a strong password. Passwords are frequently the only thing protecting our private information from prying eyes. Many websites that store your personal information (for example web mail, photo or document storage sites, and money management sites) require a password for protection. However, password-protected websites are becoming more vulnerable because often people use the same passwords on numerous sites. Strong passwords can help individuals protect themselves against hackers, identity theft and other privacy invasions. 

In most instances, it's safe to ignore admonitions to regularly change your passwords.  While once considered a security "best practice", changing your passwords regularly ranks relatively low as a means of protecting your accounts.  Of course, if you believe that your password has been breached or compromised, it is essential to change it immediately. 

Password managers can help make it easier for you to use unique and strong passwords for any website requiring a login.  You can read an analysis of the available options.  Never store an unencrypted list of passwords on or near your computer.

Password recovery methods are frequently the "weakest link", enabling a hacker to reset your password and lock you out of your account. Make sure your security questions aren't easily answerable.  It's also a good idea to have your password resets go to a separate email account designed for resets only. 

Unfortunately, experts warn that the security of passwords has never been weaker.  New hardware and techniques have contributed to a sharp rise in password cracking by hackers. 

One important method for making your passwords less vulnerable is to look for and enable two-factor authentication in your online accounts. Typically, you will enter your password and then a code will be sent to your mobile phone.  You will need to enter the code in addition to your password before you can access the account.  Twofactorauth.org has an extensive list of sites and information about whether and how they support two-factor authentication.


Be skeptical. Think before you click. Don’t open unexpected email attachments from unknown persons. Just because an email message looks like it came from someone doesn't mean that it actually did. Scammers can "spoof" the return address, making it look like the message came from someone else. If you can, check with the person who supposedly sent the message to make sure it's legitimate before opening any attachments. 

Don’t click on links embedded in email messages. It’s usually safer to go to the company’s website directly from your browser than by clicking on a link in an email message, unless you are absolutely certain that the email was actually sent by the person or company claiming to have sent the message. This will help you avoid becoming a victim of “phishing”. Phishing is the fraudulent process of attempting to acquire sensitive information by masquerading as a trustworthy entity. Phishing is typically carried out by email and often directs users to enter details at a fake website whose look and feel are almost identical to the legitimate one. 

Spear phishing is a type of phishing attack that appears to be from a colleague, employer or friend and includes a link or something to download. Spear phishing often targets senior executives at organizations that may have valuable information stored on their computers. These messages may be personalized with publicly available information about the recipient to make them look genuine. They are therefore more difficult to detect than ordinary phishing. The links or downloads included in such a message can be malicious, and might include viruses or fake websites that solicit personal information. 

No matter how official an email message looks, never access a financial account by clicking on an embedded link. If the email is fraudulent, a scammer could use the account number and password you enter to steal your identity and empty your account.  One way to protect against this is to use an incorrect password on the first try. A phishing site will accept an incorrect password, while a legitimate site won't. You should also avoid calling any telephone number in an unsolicited email unless you have confirmed that it is a legitimate number.

Avoid social engineering attacks. Social engineering can be defined as the process of obtaining information from other people through the application of social skills. The objective of social engineering is to deceive the computer user into compromising his/her system and revealing sensitive information.

Social engineering ploys take advantage of human nature by tricking people into installing malware or revealing personal information.  The user is tempted to carry out a necessary activity that damages their computer. This occurs when the user receives a message directing him/her to open a file or web page or watch a video. Often, these ploys relate to celebrities, natural disasters, or popular events.

One common trick includes showing a fake virus scan that indicates your computer is infected and encourages you to download a tool to remove the infection. Another ploy offers to display a video, but only after you install a plug-in that is “required” to view the content.

These ploys sometimes will present themselves as a pop-up. To close a pop-up, carefully click on the X on the upper right corner, not within the window itself. To avoid pop-ups altogether, enable your browser’s pop-up blocker or use pop-up blocking software.

It’s important to note that no technology is capable of protecting the computer user from social engineering. You should only install software or browser add-ons if you actually are looking for them in the first place. Always be sure that you are downloading the software directly from the source or a reliable site.

Back up all your data. While your computer may be an expensive asset, it is replaceable. However, the data and personal records on your computer may be difficult or impossible to replace. Whether or not you take steps to protect yourself, there is always the possibility that something will happen to destroy your data.

There are many hardware and software alternatives for backing up your data including USB flash drives and external hard drives (hardware) as well as archiving and disk imaging programs (software). Each method has its own advantages and disadvantages. For a simple solution, important files can be saved to an encrypted USB flash drive. It’s a good idea to keep your backup media in a locked and secure location.

Encrypt files on your computer, laptop or portable device. Computers are lost, stolen or hacked every day. As a result, your personal information can become available to anyone and may lead to privacy invasion and identity theft. Many computers and other devices contain sensitive files such as financial records, tax returns, medical histories, and other personal files.

Many computer users rely on laptops and other portable devices because they are small and easily transported. But while these characteristics make them convenient, they also make them an attractive target for thieves. Make sure to secure your portable devices to protect both the machine and the information it contains. It’s important to encrypt any sensitive data on such devices.  

USB flash drives pose security risks for similar reasons. Use them cautiously. Some flash drives offer built-in encryption features.  

Encryption is a way to enhance the security of a file or folder by scrambling the contents so that it can be read only by someone who has the appropriate encryption key to unscramble it.

Unencrypted files on your computer can be read by anyone even if your computer is password protected. There are methods by which a person who has physical access to your computer can read unencrypted files without entering your password.  So it’s important to encrypt sensitive files even if they are on a password-protected computer.

Protect sensitive information. Do not reveal personal or financial information in email, and do not respond to email solicitations for this information. This includes following links sent in email. Don't send sensitive information over the internet before checking a website's security.

6. Using Wireless Connections (Wi-Fi)

Wireless networks offer the significant advantage of enabling you to build a computer network without stringing wires. Unfortunately, many of these systems come out of the box with the security features turned off. This makes the network easy to set up, but also easy to break into. Most wireless networks use the 802.11 protocol, also known as Wi-Fi.

Security risks of using wireless data networks. Wireless networks have spawned a past-time among hobbyists and corporate spies called war-driving. The data voyeur drives around a neighborhood or office district using a laptop and free software to locate unsecured wireless networks in the vicinity, usually within 100 yards of the source. The laptop captures the data that is transmitted to and from the network's computers and printers. The data could include anything from one's household finances to business secrets.

Most home Wi-Fi access points, routers, and gateways are shipped with a default network name (known as an SSID) and default administrative credentials (username and password) to make setup as simple as possible. These default settings should be changed as soon as you set up your Wi-Fi network.  In addition, some routers are equipped by default with "Guest" accounts that can be accessed without a password.  "Guest" accounts should be disabled or password protected.

The typical automated installation process disables many security features to simplify the installation.  Not only can data be stolen, altered, or destroyed, but programs and even extra computers can be added to the unsecured network without your knowledge. This risk is highest in densely populated neighborhoods and office building complexes. 

Home networks should be secured with a minimum of WPA2 (Wi-Fi Protected Access version 2) encryption. Routers purchased in the last six years should include WPA2 security technology. Often, you have to specifically turn on WPA2 to use it. The older WEP encryption has become an easy target for hackers. Also, do not name your home network using a name that reveals your identity.

Setting up your home Wi-Fi access point can be a complex process and is well beyond the scope of this guide. To ensure that your system is secure, review your user's manuals and web resources for information on security.  The Wi-Fi Alliance offers tips for setting up a home Wi-Fi connection.

Security risks of using Wi-Fi hotspots. The number of Wi-Fi hotspot locations has grown dramatically and includes schools, libraries, cafes, airports, and hotels. With a Wi-Fi connection you can be connected to the internet almost anywhere. You can conduct the same online activities over Wi-Fi as you could at home or work, such as checking email and surfing the web.

However, you must consider the risks to your privacy and the security of your laptop or netbook when using a Wi-Fi hotspot. Most Wi-Fi hotspots are unsecured and unencrypted. This is the major security risk of Wi-Fi. Even the expensive fee-based Wi-Fi service available in many airplanes may be as insecure as the free Wi-Fi offered at your corner coffee house.  Therefore, you must take additional steps to protect your privacy.

Because the network at a Wi-Fi hotspot is unsecured, internet connections remain open to intrusion. Hackers can intercept network traffic to steal your information.

There are 3 major privacy threats in a Wi-Fi hotspot:

· Man-In-The-Middle Attack refers to the act of intercepting the connection between your computer and the wireless router that is providing the connection. In a successful attack, the hacker can collect all the information transferred and replay it on his/her computer.

· Eavesdropping refers to the act of using sniffer software to steal data that is being transmitted over the network. A sniffer is an application or device that can read, monitor, and capture network data. This is particularly dangerous when conducting transactions over the internet since sniffers can retrieve logon details as well as important information such as credit card numbers.

· Looking over the shoulder is the simple act of others peering over your shoulder to see your activities.

Protecting your privacy at a Wi-Fi hotspot: The basics. There are various ways to help protect your privacy when using Wi-Fi. Begin with basic common sense. Look around to see if anyone is surreptitiously trying to look at your computer. Do not leave your computer unattended. Never conduct unsecured transactions over unsecured Wi-Fi. When entering sensitive information (such as your Social Security number, password, or credit card number), ensure that either the website encrypts the information or that your Wi-Fi connection is encrypted. For the best protection, do not access email, online banking or other sensitive data. Disable your wireless adapter if you are not using the internet. Otherwise, you leave your computer open to vulnerabilities if it accidentally connects to the first available network. 

VPN (Virtual Private Network). This is the first line of defense against vulnerabilities created by Wi-Fi. A VPN provides encryption over an unencrypted Wi-Fi connection. It will help ensure that all web pages visited, log-on details, and contents of email messages remain encrypted. This renders intercepted traffic useless to the hacker. You can obtain software to set up a VPN through your office or home computer, or you can use a commercial provider’s hosted VPN service.

Secure surfing/SSL. When checking your email or conducting any important transaction, adding an “s” after “http” may give you a secured connection to the website. Many webmail services provide this feature. This ensures that your login details are encrypted thereby rendering it useless to hackers. Although your email login may be encrypted, some webmail providers may not encrypt your Inbox and messages.

Check for SSL (Secure Sockets Layer) certificates on all websites on which you conduct sensitive transaction. SSL creates a secure connection between a client and a server, over which any amount of data can be sent securely.  

Wi-Fi settings. Ensure that your computer is not set to automatically connect to the nearest available Wi-Fi access point. This may not necessarily be a legitimate connection point but instead an access point on a hacker’s computer. Turn off your Wi-Fi when not in use.

Disable file sharing. Make sure that file sharing is disabled on your computer to ensure that intruders cannot access your private files through the network. With file sharing enabled, it's possible for unauthorized individuals to access your files.

Firewall. Install a firewall on your computer and keep it enabled at all times when using Wi-Fi. This should prevent intrusion through the ports on the computer.

Security updates. Keep your computer’s software and operating system up-to-date. This will help plug security holes in the software or operating system.

7. Resources

Privacy Rights Clearinghouse:

· Online Privacy: Using the Internet Safely

· Online Shopping Tips: E-Commerce and You

· Social Networking Privacy: How to be Safe, Secure and Social

U.S. Government:

The U.S. Computer Emergency Readiness Team (U.S. CERT) offers numerous computer security resources.  It's Tips Page is especially useful.

The Federal Trade Commission's Start with Security: A Guide for Business describes 10 practical lessons businesses can learn from the FTC's data security settlements.

Other Useful Resources:

The National Cyber Security Alliance offers resources to help you know the basics of securing your home network and your family’s privacy

Krebs on Security offers Tools for a Safer PC.

California Attorney General, Cybersecurity in the Golden State: How California Businesses Can Protect Against and Respond to Malware, Data Breaches and Other Cyberincidents (February 2014)

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