As the name indicates, this attack is a hijack of cookies. Cookies are small text files that are created by the server and sent to the client with each page request. The main purpose of cookies is to make browsing easier for you by providing various types of information to websites such as your name, address, and search preferences so that they can customize your browsing experience based on your past visits. For example, Gmail will fill in certain suggestions automatically as soon as you start typing in a new message, without requiring you to dig through the Edit menu again and again.

Key Points: 

• Many popular websites have been affected by cookie hijacking. For instance, Flickr has been hit by a script that steals users’ passwords and sends them to an attacker’s email address.
• This type of attack occurs when the attacker embeds malicious JavaScript code into an otherwise authentic-looking email or advertisement. 
• This malicious code is then executed by the victim’s browser when they visit the infected site; it will display an endless series of popups that may be used for phishing purposes to steal your login credentials or other sensitive information. 
• In addition, some sites have also been modified so that they harvest cookie data from unsuspecting visitors without requiring them to provide their login credentials first.

Advantages: 

• Cookie hijacking is a stealthy attack. It can take place without the victim knowing anything about it because the browser will send cookies automatically to any website the user navigates to. Most computer users do not realize the importance of protecting their cookies, which is why they often fall victim to such attacks.
• Cookie hijacking attacks are hard to detect because they use seemingly authentic-looking emails or advertisements with malicious code embedded in them to spread from one user to another over time. There is no need for a hacker’s malicious server; these attacks can be carried out entirely by leveraging popular websites and email servers that people use daily for legitimate purposes as well.
• In certain cases, the attacker can do more than just steal your login credentials or other sensitive information. He can also install malicious software on your computer, make you interact with phishing sites that may attack you with ransomware, or even make you visit phony pornographic websites and more.
• Cookie hijacking is hard to detect because the user cannot be certain that they were visiting a legitimate website before any popups started appearing on their screen. Malicious JavaScript code can fool the user into thinking it was a legitimate message from one of his favorite websites that he visited earlier without realizing his cookies were hijacked at that time and sending the data from somewhere else.

Conclusion: 

Cookie hijacking is a serious threat that is often left unnoticed. If you are worried about such attacks on your computer, consider installing anti-malware software or activating the “Do Not Track” feature in your browser that protects you from cookie hijacking attacks.