When you are online, you provide information about yourself almost every step of the way. Often this information is like a puzzle with pieces that need to be connected before the full picture is revealed. Information you provide to one person or company may be combined with information you have provided to another person or company to complete the puzzle. This information can be collected through your browser while visiting websites or by the mobile apps that you use on your phone. This guide explains how your online activities may compromise your privacy and describes some of the steps you can take to protect yourself.
Our separate consumer guide Securing Your Computer to Maintain Your Privacy explains how you can be proactive about your privacy by addressing computer security vulnerabilities.
You probably have noticed that many advertisements that you see online are targeted to your tastes and interests. That's because almost every major website you visit tracks your online activity. Tracking technology can follow you from site to site, track and compile your activity, and compile all of this into a database. Generally, tracking utilizes a numerical identifier, rather than your real name. This information is used to personalize the content that you see online.
The good news is that almost all browsers give you some control over how much information is revealed, kept and stored. Generally, you can change the settings to restrict cookies and enhance your privacy. Most major browsers now offer a "Private Browsing" tool to increase your privacy. However, researchers have found that "Private Browsing" may fail to purge all traces of online activity.
Most browsers also provide a Do Not Track (DNT) setting. DNT is a way to keep your online activity from being followed across the Internet by advertisers, analytics companies and social media sites. When you turn on the DNT setting in your browser, your browser sends a special header to websites requesting that don’t want your activity tracked. Unfortunately, honoring the DNT setting is voluntary. Individual websites are not required to respect it. While a few websites will honor DNT, most websites will ignore your preference.
Some of the tools that are used to track you online include cookies, flash cookies, and fingerprinting.
Cookies. When you visit different websites, many of the sites deposit data about your visit, called "cookies," on your hard drive. Cookies are pieces of information sent by a web server to a user's browser. Cookies may include information such as login or registration identification, user preferences, online "shopping cart" information, and so on. The browser saves the information, and sends it back to the web server whenever the browser returns to the website. The web server may use the cookie to customize the display it sends to the user, or it may keep track of the different pages within the site that the user accesses.
Disconnect is a browser extension that stops major third parties from tracking the webpages you go to. Every time you visit a site, Disconnect automatically detects when your browser tries to make a connection to anything other than the site you are visiting. You can also opt-out of the sharing of cookie data with members of the Network Advertising Initiative.
Flash cookies. Many websites utilize a type of cookie called a "flash cookie" (sometimes also called 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. They cannot be deleted by any commercially available anti-spyware or adware removal program. However, if you use the Firefox browser, there is an add-on called Better Privacy that can assist in deleting flash cookies.
Fingerprinting. A device fingerprint (or machine fingerprint) is a summary of the software and hardware settings collected from a computer or other device. Each device has a different clock setting, fonts, software and other characteristics that make it unique. When you go online, your device broadcasts these details, which can can be collected and pieced together to form a unique "fingerprint" for that particular device. That fingerprint can then be assigned an identifying number, and used for similar purposes as a cookie.
Fingerprinting is rapidly replacing cookies as a means of tracking. Tracking companies are embracing fingerprinting because it is tougher to block than cookies. Cookies are subject to deletion and expiration, and are rendered useless if a user decides to switch to a new browser. Some browsers block third-party cookies by default and certain browser add-ons enable blocking or removal of cookies.
Unlike cookies and flash cookies, fingerprints leave no evidence on a user's computer. Therefore, it is impossible for you to know when you are being tracked by fingerprinting.
You can test your browser to see how unique it is based on the information that it will share with the sites that you visit. Panopticlick will give you a uniqueness score, letting you see how easily identifiable you might be as you surf the web.
Cross-device tracking. Cross-device tracking occurs when companies try to connect a consumer’s activity across their smartphones, tablets, desktop computers, and other connected devices. The goal of cross-device tracking is to enable companies to link a consumer’s behavior across all of their devices. While this information serves many purposes, it is particularly valuable to advertisers.
To engage in cross-device tracking, companies use a mixture of both “deterministic” and “probabilistic” techniques. The former can track you through an identifying characteristic such as a login. The later uses a probabilistic approach to infer which consumer is using a device, even when a consumer has not logged into a service.
For example, a company called BlueCava is able to identify and track users online across multiple devices. They can associate multiple devices to the same person or household, by attaching an IP address to a BlueCava identifier and by recognizing and collecting information about the various computers, smartphones, and tablets that people use to connect the internet. Thus, your behavior on one device can be associated with other devices from both your home and office. This information can be very valuable for marketing purposes.
BlueCava's technology enables them to recognize computers and devices by collecting information about your screen type, IP address, browser version, time zone, fonts installed, browser plug-ins and various other properties of your screen and browser. This information is put into a “snapshot” and is sent to their servers to create a unique ID for every browser and to “match” the snapshot to the snapshots they receive from their marketing partners. When they use snapshots to create a unique ID, they are also able to group related screens into “households” based on common characteristics among the snapshots, such as IP addresses. BlueCava allows you to opt out of tracking.
If you are interested in some of the more technical aspects of online tracking, the Princeton Web Census measures cookie-based and fingerprinting-based tracking at one million websites and evaluates the effect of browser privacy tools.
If you use a smartphone or other mobile device to access the Internet, chances are that you may be using mobile applications (apps) rather than an Internet browser for many online activities. An app is a program you can download and access directly using your mobile device. There are hundreds of thousands of apps available, including numerous free or low-priced choices. Unfortunately, apps can collect all sorts of data and transmit it to the app-maker and/or third-party advertisers. This data may then be shared or sold.
Some of the data points that an app may access from your smartphone or mobile device include:
- your phone and email contacts
- call logs
- internet data
- calendar data
- data about the device’s location
- the device’s unique IDs
- information about how you use the app itself
Many apps track your location. There are location-based services like Yelp and Foursquare that may need your location in order to function properly. However, there are also apps (such as a simple flashlight) that do not need your location to function and yet still track it.
Smartphones and other mobile devices may ask you for specific permissions when you install an app. Read these and think about what the app is asking for permission to access. Ask yourself, “Is this app requesting access to only the data it needs to function?” If the answer is no, don’t download it. Learn where to go on your particular phone to determine what you will allow the app to access, and if you are at all suspicious do more research on the app before you download.
Mobile apps generally do not provide ad networks with the ability to set a cookie to track users. Instead, ad networks may use your phone's mobile advertising identifier. These identifiers have different names depending on the brand of your phone. For example, on Android devices they are called Google Advertising ID. On iOS, they are called Identifiers for Advertisers. You can find your device's options to set an opt-out flag using these instructions.
According to the California Attorney General, a website, app, or other online service may violate this law if:
The California Attorney General operates an online complaint form that consumers may use to report violations.
You are likely to access the internet using one or more of these services:
- An Internet Service Provider (ISP)
- A Mobile (Cellular) Phone Carrier
- A Wi-Fi Hotspot
If you use a computer to access the internet and pay for the service yourself, you signed up with an Internet Service Provider (ISP). Your ISP provides the mechanism for connecting to the internet.
Each computer connected to the internet, including yours, has a unique address, known as an IP address (Internet Protocol address). It takes the form of four sets of numbers separated by dots, for example: 126.96.36.1990. It’s that number that actually allows you to send and receive information over the internet.
Depending upon your type of service, your IP address may be "dynamic", that is, one that changes periodically, or "static", one that is permanently assigned to you for as long as you maintain your service.
Your IP address by itself doesn’t provide personally identifiable information. However, because your ISP knows your IP address, it is a possible weak link when it comes to protecting your privacy. ISPs have widely varying policies for how long they store IP addresses. Unfortunately, many ISPs do not disclose their data retention policies. This can make it difficult to shop for a “privacy-friendly” ISP. Some ISPs may share their customers’ internet activity with third parties and/or collect your browsing history to deliver targeted advertisements.
When you visit a website, the site can see your IP address. Your IP address can let a site know your geographical region. The level of accuracy depends upon how your ISP assigns IP addresses.
You can block your IP address by utilizing a service such as Tor which effectively blocks this information. Another alternative is to use a Virtual Private Network (VPN). A VPN replaces your IP address with one from the VPN provider. A VPN subscriber can obtain an IP address from any gateway city the VPN service provides. You will have to pick a VPN provider very carefully. Unfortunately, experts can’t agree upon which VPN services are best. Some VPNs have potential security flaws that could put your data at risk. It can be difficult to determine how secure a VPN is, and precisely what it is doing with your data. Most experts advise avoiding free VPNs, which may monetize your data in exchange for the free service.
If you access the internet with a phone or other mobile device, you may access the internet using a data plan tied to your cellular phone service. If you have a data plan, your service provider (such as AT&T, Sprint, Verizon, and T-Mobile) collects data about your usage.
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 the first line of defense against the compromise of your digital information. Revealing the data on your phone, your banking information, your email, your medical records, or other personal information could be devastating. Yet many people fail to follow proper practices when selecting the passwords to protect this important information. 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.
Here are some password “dos” and “don’ts” that can help you to maintain the security of your personal data.
- Do use longer passwords. Passwords become harder to crack with each character that you add, so longer passwords are better than shorter ones. A brute-force attack can easily defeat a short password.
- Do use special characters, such as $, #, and &. Most passwords are case sensitive, so use a mixture of upper case and lower case letters, as well as numbers. An online password checker can help you determine the strength of your password.
- Don’t "recycle" a password. Password-protected sites are often vulnerable because people often use the same passwords on numerous sites. If your password is breached, your other accounts could be put at risk if you use the same passwords.
- Don’t use personal information (your name, birthday, Social Security number, pet’s name, etc.), common sequences, such as numbers or letters in sequential order or repetitive numbers or letters, dictionary words, or “popular” passwords.
- Don’t feel obligated to change your passwords frequently, unless you believe that your password has been stolen or breached. Conventional wisdom considered changing passwords to be an important security practice. Recent research suggests that people who change their passwords frequently select weaker passwords to begin with, and then change them in predictable ways. Of course, if you believe that your password has been breached or compromised, it is essential to change it immediately.
- Don’t share your passwords with others.
- Do enable two-factor authentication (when available) for your online accounts. Typically, you will enter your password and then a code will be sent to your 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. It's best to use an option that isn't SMS-based, such as an authentication app on your smartphone.
- Don’t write down your passwords or save them in a computer file or email. Consider a password manager program if you can’t remember your passwords. Alternatively, keep a list of passwords in a locked and secure location, such as a safe deposit box.
Password recovery methods are frequently the "weakest link", enabling a hacker to reset your password and lock you out of your account. Be sure that you don’t pick a question which can be answered by others. Many times, answers to these questions (such as a pet’s name or where you went to high school) can be ascertained by others through social networking or other simple research tools. It's also a good idea to have your password resets go to a separate email account designed for resets only.
Households and businesses establish wireless networks to link multiple computers, printers, and other devices and may provide public access to their networks by establishing Wi-Fi hotspots. A wireless network offers the significant advantage of enabling you to build a computer network without stringing wires. Unfortunately, these systems usually 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 home wireless 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. You may 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 fact sheet. To ensure that your system is secure, review your user's manuals and web resources for information on security.
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 would be able to 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 device when using a Wi-Fi hotspot. Most Wi-Fi hotspots are unsecured and unencrypted. Even the expensive pay 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 them on his 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 looking over your shoulder to see your activities.
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 webpage encrypts the information or that your Wi-Fi connection is encrypted. 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. This 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 webpage. 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.
Disable file-sharing. Ensure that file sharing is disabled on your computer to ensure that intruders cannot access your private files through the network.
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.
Using Search Engines
It's a good idea to avoid using the same website for both your web-based email and as your search engine. Web email accounts will always require some type of a login, so if you use the same site as your search engine, your searches can be connected to your email account. By using different websites for different needs -- perhaps Yahoo for your email and Google for your searches -- you can help limit the total amount of information retained by any one site. Alternatively, log out of your email and clear your browser's cookies before going to other sites, so that your searches and browsing are not connected to your email address. Another method for preventing a search engine from associating your searches and web browsing with your web mail account is to use a different browser for your email account than for your searches and web browsing.
Avoid downloading search engine toolbars (for example, the Google toolbar or Yahoo toolbar). Toolbars may permit the collection of information about your web surfing habits. Watch out that you do not inadvertently download a toolbar when downloading software, particularly free software.
When you correspond through email you are no doubt aware that you are giving information to the recipient. You might also be giving information to any number of people, including your employer, the government, your email provider, and anybody that the recipient passes your message to. An unencrypted email message can potentially be seen by anyone while in transit. If sent from an employer-owned device, it could be read by your employer.
If you use a webmail service such as Gmail or Yahoo, your emails could be scanned by the webmail provider, both to detect spam and to deliver advertising content. Gmail scans incoming emails and places relevant advertisements next to the email. Yahoo Mail says that it performs "automated content scanning and analyzing of your communications content.” If your recipient uses Gmail, Google will scan your message and provide advertisements to the recipient even if you, the sender, do not use Gmail.
Any website or app can determine the approximate location of your computer or device by using one of several technologies. If you are using a computer, your IP address can identify your approximate location. Most IP addresses can identify you by your city or metropolitan area. Some can identify a more specific location.
You can block your IP address by utilizing a service such as Tor which effectively blocks this information. Another alternative is to use a Virtual Private Network (VPN). A VPN replaces your IP address with one from the VPN provider. A VPN subscriber can obtain an IP address from any gateway city the VPN service provides.
If you are using a wireless connection, Wi-Fi triangulation can determine your location by surveying nearby wireless networks. Similarly, GPS triangulation can determine your location from a network of satellites. GPS triangulation is more accurate than Wi-Fi triangulation. Finally, cell phone tower identification can determine the location of a smartphone.
Your location information might be used for a useful purpose, for example, providing accurate travel directions. However, it may also be stored and combined with other information about you and used for behavioral marketing and other purposes.
Location information can pose a significant privacy risk, particularly when it is stored or combined with other information about you. It can reveal your whereabouts at any given time, including your presence at sensitive locations. It can be dangerous for individuals who are stalking or domestic violence victims.
It is very easy to get duped into clicking on a malicious link. If you click on a malicious link, you will most likely be taken to a site that tricks you into providing personal information that can then be used to steal your money, or even worse, your identity. Clicking on a dangerous link could also cause malware to automatically download onto your computer.
Malicious links may look like they were sent by someone you trust, such as:
- A friend or someone who you know.
- A legitimate-looking company selling a product or service.
- A bank or other business that you have an existing account with.
Most people think that malicious links arrive by email. But, criminals are finding even sneakier ways to trick you into clicking on a dangerous link. You could receive the malicious link in an instant message, a text message, or on a social networking site like Facebook or Twitter.
Malicious links are hard to spot. They often:
- Are ever-so-slightly misspelled versions of well-known URLs.
- Use popular URL shortener sites to hide the real URL.
- Use simple HTML formatting to hide the real URL. This is the most common method for emailed dangerous links. You think you’re clicking on a trustworthy link, but you are redirected to a dangerous link.
To protect yourself from malicious links, consider the following tips:
- Do not click on a link that appears to be randomly sent by someone you know, especially if there is no explanation for why the link was sent, or if the explanation is out of character for the sender (i.e. horribly misspelled or talking about what a great deal they discovered).
- Do not click on a link that was sent to you by a business you don’t know that is advertising a great deal. Instead, perform an online search for the business, make sure it’s legitimate, and go directly to the business’ website to find the deal yourself.
- Do not click on a link that was sent to you by a business you have an existing account with. Either go to the business’ site yourself, or call up the business and confirm the legitimacy of the link.
- Note that some businesses may require that you verify your email address as part of a registration process, which requires you to click on a link contained in an email. Typically, the link will be emailed to you immediately after you register online with the business. It’s a good idea to check your email right after you register with a business.
The Federal Trade Commission (FTC) is the federal government's primary agency for online privacy oversight. The FTC’s Onguard Online website offers tips for avoiding internet fraud, securing your computer and ways to protect your personal information.
The U.S. Computer Emergency Readiness Team (U.S. CERT) offers numerous computer security tips.