Internet cookies have existed since the mid-90s and early online stores’ first shopping carts. They continue to shape the modern online experience, yet can also pose a threat. This article will tell you all about the concept of cookie theft, how it works, and what you can do to stay safe.

Cookies – A Necessary Risk

Cookies remain one of many websites’ most fundamental and convenient building blocks. Without the first-party kind, you couldn’t jump between a website’s pages and remain logged in or keep items in your shopping cart for days. Such cookies also provide websites with location data useful for current information like local weather, game scores, etc.

Cookies store information about your activity inside text files local to your device. They often contain session IDs, which is why cookie theft and session hijacking overlap a great deal.


What happens if someone steals your session cookies?

It depends on your site and the specific information the cookie stores. Such cookies need to keep you logged on, so the chances of stealing your username and password are high. The specific website might only require a signup, so the above info could be of limited use. However, cookies that contain logins for social media or online store accounts could expose much of your personally identifiable and credit card information.

How Does Cookie Theft Work?

Hackers can steal cookies in several ways. Most methods depend on irresponsible user activity, but some may also target website code vulnerabilities.

Man-in-the-middle attacks

MITM attacks happen when a malicious person with access to a network you’re on intercepts and spies on your communication. Public Wi-Fi is highly susceptible to such attacks since the security of such networks is low or non-existent. The lack of encryption means any information you enter or receive is visible to anyone who might be eavesdropping. The perp only needs to capture your session cookie and can then access your account without needing to log in.

You retain some degree of security even when using unprotected connections since most sites rely on encrypted communication facilitated through SSL. However, savvy cyber crooks can trick a site into switching to the less secure HTTP protocol and allow cookie theft that way.


Users can also fall victim to cookie theft if their devices get infected with malware. This can happen after they visit an infected site or interact with phishing emails that contain infected links. The risks of phishing attacks include a variety of damaging outcomes. These range from attackers harvesting sensitive information you enter on fraudulent websites, to gaining control over your online sessions. In some extreme cases, they may even lock you out of your device, demanding payment to restore access.

Websites vulnerable to cross-site scripting

You could be practicing good cybersecurity hygiene and still fall victim to cookie theft due to poorly coded websites. Cross-site Scripting, or XSS, is an attack that exploits legitimate and seemingly harmless websites by injecting them with malicious code.

It’s particularly devious since neither the site nor the user can detect irregularities. Your browser believes it can trust the website and will display any malicious popups or fields the infected website instructs it to. Hackers can then steal your session data. It’s bad enough if you’re a regular user, but they can also get their hands on admin credentials this way and take the site over entirely in a worst-case scenario.

What Can You Do Against Cookie Theft?

While annoying and dangerous, cookie theft can be prevented if you use the correct precautions.

Install and use a VPN

Going online via public Wi-Fi is among the most common causes of cookie theft due to the lackluster state of such a network’s security. While avoiding public Wi-Fi is the best practice, you can’t always go out of your way to do so. That’s why you need a virtual private network.

VPNs address public Wi-Fi’s chief security vulnerability – the lack of connection encryption. VPNs use state-of-the-art encryption algorithms to turn the data you send and receive into unreadable nonsense for anyone lacking the decryption key. They’re also great for browsing the web anonymously and connecting to servers worldwide to bypass geographical restrictions.

However, there is a burning debate about using proxies or VPNs. Here is a short breakdown of a comparison of a proxy server and a VPN:

Proxies are often faster and require less configuration, making them appealing for tasks that need quick IP address changes without the need for encrypted communication. On the other hand, VPNs, with their comprehensive encryption, are indispensable for users demanding high security and privacy, especially when accessing sensitive information over insecure networks.

Protect your accounts with MFA

Hackers realize they have little time to do their dirty work once they steal your cookies. That’s why they’ll often try to change the password and email associated with the account they just took over. A regular password is useless in that case, but the multifactor authentication you set up beforehand may still save it.

Enabling MFA imposes another check before letting users access the account from new locations or devices. Some use biometrics; others send codes to authenticator apps or your phone. Either way, the lockout allows you to change the compromised credentials. However, it won’t stop the crooks from stealing any info they accessed before attempting the password change.


Keep your antimalware software and browser updated

Multifactor authentication won’t help with cookie theft variants like man-in-the-browser attacks. Luckily, antimalware programs may detect the responsible code before it can cause harm. New versions of such attacks are a constant threat, even more so now that their creators can use AI to help their malware adapt and mutate.

Ensuring that your OS, browser, and antimalware protection are up to date is the only way to keep up.


Google might be paving the way for a future without third-party advertiser cookies. Still, the first-party cookies websites rely on to function correctly are here to stay. That’s why it’s important to adopt cybersecurity best practices and remain vigilant so the threat of cookie theft doesn’t compromise your accounts, personal information, and more.