HomeTutorialsSession Hijacking: Everything You Need To Know

Session Hijacking: Everything You Need To Know

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Here, I will show you everything you need to know about session hijacking.

When a visitor lands on a site, the first thing that happens between the user and the site is session creation. The website authenticates the user, and the session is created. Sessions are an essential part of communication between two parties. Session IDs are usually stored in the form of cookies. If the hackers can get these cookies, they can take over the user session and use the session ID on that website to do a lot of damage without being detected.

What Is Session Hijacking?

Session hijacking occurs when a scammer steals the session information from HTTP cookies, URL, page header, or active session body. In this way, the web users’ session is stolen from him by the attacker who pretends to be the real user and can do anything the user has the privilege to do on the network. During a single connection, the series of interactions between two communicating parties is called a session. When you log into an application, a session is generated on the webserver for other requests coming from the same user to manage the series of current interactions.

Sessions are used by these applications to keep the appropriate information of the client. For the time, the user stays active on a network, the session remains alive. Once the user has logged out or has not performed any activity for a while, the session gets destroyed. A session ID is made up of a long random mixture of alphabets and numerals. These are preserved in cookies, web pages, etc. As the intruder typically attacks the session cookie, it is also called cookie hijacking.

How Does Session Hijacking Work?

How Does Session Hijacking Work

Session hijacking is almost similar to plane hijacking. In an airplane hijacking, the attackers launch a systematic attack on the plane and take control of it. The same happens in session hijacking. There are different ways of session hijacking, as mentioned below:

  • Session Sniffing
  • Cross-site Scripting (XSS)
  • Session Fixation
  • Man in the Browser
  • Predictable Session ID

1. Session Sniffing

When the communication between the user and the webserver is insecure, and the session ID is being sent in unencrypted form, the intruder can take advantage of this and steal the session ID that he/she can use for malicious. Some tools like Wireshark, OWASP Zed can be used by the hackers to monitor information flow containing session ID between the client and the server. Once they get the session ID, they can access the session without authorization.

2. Cross-site Scripting (XSS)

Cross-site Scripting (XSS)

Cross-site scripting is one of the most dangerous techniques used for session hijacking. The attacker adds the malicious code on a real website or an application to inject the user’s web browser's spiteful scripts. When the user visits that site or opens that application, he is attacked by the scammers. The malicious code can be in the form of messages, forums, links, etc., on a legitimate server.

3. Session Fixation

To deceive the users, the hackers may send them a known session ID. It can be done by sending a link through email. When the users click on the link, they are directed to a legal login form. The user confirms the connection and becomes a victim of session hijacking by the scammers' session key.

4. Man in the Browser

A man-in-the-browser attack works by infecting the users’ computer with a Trojan (a virus that is often assumed to be genuine software). When the user installs the software and visits a target site, the session gets hijacked by the attacker. The man in the browser can do anything with transactions the user can perform. They can make the new transactions, and the web server will not be able to identify that the process is not valid because comes from the user’s computer.

5. Predictable Session ID

Many websites use easy algorithms to create a session ID. If the hacker monitors various session IDs, then he may be able to predict valid session IDs.

Protection Against Session Hijacking

Here are the tips that are used to prevent session hijacking:

1. Install an SSL Certificate

Install an SSL Certificate

A lot of data transmission happens between the user and the server during a session. If the website does not have an SSL certificate, then the information is not secure, and hackers can easily read it. So, the login information shared through this non-secure connection can be taken over by the attacker.

If you install an SSL (Secure Sockets Layer) on your website, then the data transmission is encrypted and beyond scammers'. Even though, if someone gets to the encrypted data being exchanged, he/she will be unable to read and understand this, as they cannot decrypt the information.

You can buy an SSL certificate from any popular SSL certificate providers like Comodo, DigiCert, Symantec, GeoTrust, etc. However, if your site has one domain and multiple sub-domains, then you should consider buying a DigiCert wildcard SSL certificate.

2. Security Plugins

Installing security plugins can help you stay protected from hacking. Whenever a hacker sends malware or spiteful code on your site, the plugin’s firewall will alert you about this activity and you will be able to block it before falling prey to it.

3. Update and Harden your Website

Keep updating your website whenever a new update is available. If you are running an outdated server software, then the hacker may find any vulnerabilities in it and may harm you. You should use strong usernames, passwords, blocking PHP execution, etc., to harden your website.

How Can Users Safeguard Themselves from Cookie Stealing?

As a user, you must take security precautions that are mentioned below while visiting a website:

1. Anti-virus Installation

You should install antivirus software on your computer. This software keeps an eye on everything you download from the internet or transfer through flash drives. When you visit a suspicious website, they inform you of the alarming content present on that site.

2. Avoid Clicking Suspicious Links

The hackers can send you links through emails or comment sections on the website. Do not click on any un-trusted links and especially those that woo you with prizes and rewards.

3. Do not Store Sensitive Information

It is a convenient way to save your passwords on the browsers to auto-login on the websites. Likewise, you can save your credit card/banking details on the shopping websites for faster checkouts. It will surely save your time but can put you in danger as well. There is a huge risk of your data being stolen. So, it is strongly recommended that you should not save your sensitive information on your browser.

4. Clear Cookies

Clear browser Cookies

If you are using Google Chrome, go to history, select “Clear browsing history” and tick the checkbox “clear cookies and other site data”. Select the time range of your choice and click ‘clear data’ and all the cookies in the selected period will be removed. This will remove any sensitive information stored on the browser.

Rounding Up

Managing an online business is not an easy task. There are hundreds of things that you need to take care of while running an online trade. You should take all the security precautions to keep your website, business, clients, and customers safe from any form of attack. You cannot ignore the security aspects, as it will ruin your business. As an internet user you can clearly see that you need to protect your site/computer from session hijacking risks while being online. Do not forget the above-mentioned important tips to stay safe while browsing.


Gina Lynch
Gina Lynch
Gina Lynch is a VPN expert and online privacy advocate who stands for the right to online freedom. She is highly knowledgeable in the field of cybersecurity, with years of experience in researching and writing about the topic. Gina is a strong advocate of digital privacy and strives to educate the public on the importance of keeping their data secure and private. She has become a trusted expert in the field and continues to share her knowledge and advice to help others protect their online identities.


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