What Is Cookie Theft? Definition and Prevention

Reading time: 7 min read
Maxym Chekalov
Written by
Maxym Chekalov

Updated · Nov 16, 2023

Maxym Chekalov
SEO Specialist | Joined June 2023 | LinkedIn
Maxym Chekalov

With a master's degree in telecommunications and over 15 years of working experience in telecommunic... | See full bio

Girlie Defensor
Edited by
Girlie Defensor


Girlie Defensor
Joined June 2023
Girlie Defensor

Girlie is an accomplished writer with an interest in technology and literature. With years of experi... | See full bio

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If you enjoy surfing the web, chances are you've encountered familiar website pop-ups requesting permission to accept "cookies."

Internet cookies are small text files that websites store on your device, containing valuable information that hackers seek to exploit.

Despite being non-edible, these cookies are of great interest to hackers who use them as a gateway to deploy cyberattacks.

Read further below to learn what cookie theft is and how to prevent cyber criminals from grabbing it.

Key Takeaways: 

  • Cookies are sought-after for their wide range of valuable information. They are helpful for both businesses and website users.
  • A cookie can be stolen in many ways.
  • Stealing browser cookies may be just as good as stealing a password.
  • Preventing cookie theft involves deleting cookies, avoiding public Wi-Fi or clicking malicious links, and using antivirus software.

What Are Cookies?

Internet cookies play a crucial role in enhancing your online experience. Websites place these small files on your computer or mobile device to store information about your preferences. So, when you encounter websites asking you to accept their cookies, there's a good reason behind it.

By accepting cookies, websites can work more efficiently and effectively. They enable seamless usability by keeping you logged in as you navigate from one page to another, ensuring a smoother browsing experience.

Here are some of the reasons why websites use cookies:

  • Keep you logged in on a site
  • Help auto-fill information in forms
  • Authenticate your identity
  • Track items you view in an online store and help you remember things in your cart
  • Remember if specific settings are turned on, like your chosen language preference and themes
  • Create highly targeted ads
  • Track how you interact with a website or an ad
  • Make personalized content recommendations
  • Prevent fraud and protect your information as you interact with a service
  • Save your preferred site settings and themes
  • Collect insights for improving the site, products, and services

While most cookies are indeed helpful and safe, they can also be used to track your activity without your consent. 

Cookies have a variety of information about you, including the following:

  • Your browsing history
  • Personally identifiable information such as your session ID (a randomly generated number that stores the session cookies temporarily), name, email address, phone number
  • Other personal data you entered as login details

Fun fact: 

Your name and email address are considered Personal Identifiable Information (PII) per the U.S. Department of Labor's Guidance on the Protection of Personal Identifiable Information.

It's important to mention that no federal law surrounds using cookies in the United States. However, some states, such as California, do regulate its use. 

The California Consumer Privacy Act (CCPA) and California Privacy Rights Act (CPRA) regulate cookie usage in California.

Given the amount of data that cookies collect, it can become a privacy concern. Cookie theft is becoming a real concern in the world today. In the following section, understand cookie theft and how to prevent it. 

Cookie theft is a cyber attack in which a bad actor steals your browser cookies. Since cookies have your personally identifiable information, anyone accessing them can also access your accounts.

A phishing campaign in 2021 using cookie theft malware targeted several Youtube content creators. User accounts that have stored session cookies in the browser were accessed.

Cookie thieves then stole session IDs which they used to spoof the Youtuber's cookie over the same network.

What is a Session ID? 

A session ID is a unique string of numbers generated by a website's server. It is assigned to users when they log in or visit so websites can remember or track them. 

This isn’t the only way cookies are stolen. Cybercriminals use many other methods to steal different cookies. 

Common Ways Employed in Stealing Cookies

Cookie thieves can intrusively steal your data and use it to impersonate you. Their strategies often include hijacking session IDs from your cookies. 

Session IDs allow users to be identified on a website. When a hacker gains access to your session ID, it makes them look like a properly logged-in user, gaining unauthorized access to the account.

Here's a list of how cookies are commonly stolen involving session IDs:

  • Session fixation. Session fixation is when an attacker sends you a malicious link via email. When you log in to your account by clicking on that link, the attacker will know your session ID, letting them take over your session.
  • Brute force attacks. Brute force attacks are used to initiate session hijacking. When a cybercriminal gains unauthorized access to your session, such as while paying bills or shopping online, and steal your Personally Identifiable Information. 

Fun fact: 

Hackers have a higher success rate of guessing your session ID if it is sequential or based on easily predictable variables like your IP address or the current time.

  • Malware injections. Website software can install malware programs to spy on traffic and steal cookies. When a malicious code tracks your browser, it can copy and exploit your cookie information.
  • Cross-site scripting (XSS) attacks. This is a client-side code injection attack where the attacker injects malicious code onto a legitimate website that will execute when you load the website. When it runs in your browser, it steals your cookies.

Cybercriminals have a lot of ways to gain unauthorized access to your cookies. Let’s discover how to prevent them from doing so.

Cookies are not harmful but create opportunities for hackers to act on their malicious intentions. These cookies are tied to your identity and authentication, making them more valuable for hackers.

Follow these steps to protect your cookies from cookie thieves:

  • Delete your cookies. While deleting cookies logs you out of all the websites you are currently logged into, there’s nothing to steal if there are no cookies. Some cookie cleaners have a quick one-click clearing option for convenience.

          Third-party cookies or cookies generated by a website other than the one you are currently visiting add            to your cyberattack vulnerability.

          You can delete them if they’re already stored on your browser.

  • Avoid using public Wi-Fi. Choose Private over Public Wi-Fi, as public wifis makes it easy for attackers to sneak cookie-stealing malware into your device. Don't do sensitive transactions such as banking and logging into an email or social media accounts with it.
  • Avoid clicking malicious links. Clicking on a suspicious link is very risky, don't do it, especially if you're not expecting one. Links could contain malware that can steal cookies, infect your device, and destroy all data.
  • Find good antivirus software. Malware like spyware not only spy on your browsing sessions but also steal your cookies. 

Quick tip:

Invest in powerful antivirus software that quarantines suspicious files.

Most antiviruses do regular scans other than just scanning programs as they enter your device. Our antivirus reviews might help you decide which to pick.

Wrapping Up

Cookies serve as tools that allow browsers to remember information related to website visits. When a website utilizes cookies, it collects certain data about your interactions.

However, it's essential to be cautious about cookie theft, a common online threat. To safeguard yourself from such risks, follow the tips provided above. 

Implementing these measures will help prevent unauthorized access to your cookies and ensure a more secure browsing experience, allowing you to protect your valuable data effectively.


Is it OK to accept cookies?

Yes, most cookies are inherently safe. They help enhance your browsing experience. It's what businesses do with cookies that give them a bad reputation.

Should I accept cookies?

Even though most cookies are inherently safe, you do not always have to accept them. Cybersecurity experts say these are situations where you shouldn't when browsing sites where you do your banking and browsing sites where you access your medical information or other private information.

What will happen if we accept cookies?

When you allow or accept cookies, you consent to give your information to the website owner or advertising company.

Is it safe to reject cookies?

Yes. If you are worried about your data safety, you can clear your cache, reject cookies and give only trusted websites access.

What happens if I block all cookies?

Blocking all cookies may stop web pages from working, or their features might be inaccessible. You might encounter a message that cookies are required to proceed or a notification that your browser cookies are turned off.


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