What Is Session Hijacking Attack and How To Prevent It?

What Is Session Hijacking Attack and How To Prevent It?

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Anshuman Singh
Senior Executive - Content
Updated on Feb 27, 2024 14:12 IST

Many people’s daily routines include logging into websites; whenever you log into one, a session is created each time. Attackers seek sessions in which they can gain unauthorized access to your accounts and steal your data. You should always authenticate your login credentials in a protected manner to avoid session hijacking attacks.


So, what exactly is a session hijacking attack? Before answering this question, let’s go through the topics that we will be covering in this blog:

What is a session?

Before we get into what a session hijacking attack is, let’s first define a session. A session is the total amount of time spent on an activity, such as the time it takes to log into your bank account for the first time and then log out after your transaction.

What is a session hijacking attack? 

Now, what exactly is a session hijacking? A session hijacking attack is a type of cyberattack in which a malicious hacker places himself between your computer and the website’s server while you are active in order to steal it.

Cookie hijacking or cookie side-jacking is another term for a session hijacking attack. And this is because an attacker can gain access to your session cookie, allowing him to imitate and carry out actions on your behalf.

An attacker can quickly transfer your money to his account, fill up the cart and pay with your credit card, steal your company’s sensitive data, and much more with the help of this attack. The hacker actively monitors everything that occurs on your account and even has the power to kick you out and take control.

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Types of session hijacking attack 

There are three types of session hijacking, such as:

Active: In active session hijacking, an attacker takes control of an active network connection. An attacker can disrupt information exchange between a server and a client in several ways. Intruders typically send massive amounts of traffic in order to disrupt a valid session by potentially triggering a denial of service (DoS) attack.

Passive: In passive session hijacking, an attacker observes the information exchange between a server and a client but does not takes over an active connection. The primary goal of passive attacks is to grab exchanged information and utilize it for evil purposes.

Hybrid: In hybrid session hijacking, an attacker monitors network traffic until they discover a problem, takes over the session and begins imitating a legitimate user. This type of session hijacking attack combines active and passive techniques.

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How does a session hijacking attack work? 

Let’s try to understand the working of a session hijacking attack with an example:

Suppose an unaware internet user (Atul) logs into an account. Atul may access a bank account, a credit card site, an online store, or any other application or site. In the browser that Atul is using, the site he is accessing will place a temporary “session cookie.” That cookie includes data about the user, allowing the site to keep them authenticated and logged in while monitoring their session activity. The session cookie remains in the search engine until the user logs out or is automatically logged out.

Suppose an attacker (John) aims to steal Atul’s sessions either by stealing Atul’s session cookie or locating the session ID within the cookie and then using that information to hijack the session. Once John has obtained the session ID, he can take control of the session without being detected. John can use the ongoing session to commit various nefarious acts, including stealing money from the user’s bank account, purchasing items, stealing personal information to commit ID theft, encoding data and demanding a ransom to decrypt it, and so on.

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Ways/Methods to accomplish a session hijacking attack 

There are many ways to accomplish this attack. Let’s go through some of the most common ones:

Session sniffing

In this attack, an attacker captures network traffic containing the session ID between a website and a client using software such as Wireshark or a proxy. Once the attacker captures this value, he can use this valid token to gain unauthorized access.


Cross-site scripting (XSS)

In this attack, an attacker takes advantage of weak security spots in a web server and injects scripts into web pages. For example, An attacker sends a customized link to the victim containing malicious JavaScript. And, when the victim clicks the link, the JavaScript runs and completes the attacker’s instructions. Hence, reveal your session key to the attacker so they can take over the session.

Brute Force attack

In this type of attack, the attacker attempts to guess the session ID until he succeeds, and once he succeeds, he uses it to hijack the session. These attacks generally work only if a website’s security is poorly enforced and session keys are short and quick to guess.


An attacker can trap you into clicking on a link that deploys malware on your device. Thus, they can hijack a session by locating it through sniffing. Once the session is detected, the malware steals the session cookie and transmits it back to the attacker. And from that data, the attacker can obtain your session ID and hijack your session. The man-in-the-middle attack is one example of such a type of attack.

Session fixation

In this attack, an attacker creates a session ID and tricks the user into initiating a session with it. In this, an attacker primarily provides a session key and spoofs the user into accessing a vulnerable server. One standard method is to send the user an email that includes a link to a login screen for the website the attacker wishes to access.

Man-in-the-browser attack

In this attack, an attacker installs a Trojan horse on the victim’s computer that is capable of altering that user’s web transactions. As the requests are introduced from the user’s computer, the web service has difficulty detecting that they are bogus. This attack’s goal includes eavesdropping, data theft, session tampering, and much more.

Consequences of session hijacking attack 

Session hijacking can have several dangerous consequences. The most dangerous consequence of session hijacking is that the malicious attacker can gain entry to the server and access its data without first hacking a valid account. Aside from all of this, an attacker will be able to engage in a variety of activities, such as:

  • Stealing personal information: Session hijacking allows attackers to access confidential information such as passwords, credit card numbers, Aadhar numbers, etc. With such information, an attacker can efficiently execute an identity theft attack or financial fraud.
  • Infecting a system with malware: Using a stolen session ID, an attacker can infect the user’s computer with malware. As a result, they gain control of the target’s computer and steal their data.
  • Executing the Denial-of-Service (DoS) attack: A hacker who gains control of a user’s session may launch a DoS attack against the website to which they are connected. As a result, the service may be disrupted, or the site may even crash.

Laws in India against session hijacking attack 

In India, there is no specific law governing session hijacking. However, if you are a victim of this attack, you can report the incident to the nearest police station under Section 43 of the IT Act.

If a person accesses, downloads, copies, or extracts any data without the permission of the owner or any other person in charge of a computer, computer system, or computer network, that person is liable to pay a penalty of up to ₹ 5,00,000/-, or imprisonment for up to 3 years, or both. The punishment is the same even when a person denies or causes the denial of access to data by any authorized person. 

How to prevent session hijacking attack 

Some of the most common ways to prevent session hijacking attacks are:

  • Share session IDs with only trusted sources. Remember that session id may be included when sharing links or sending requests to websites.
  • Using a VPN prevents attackers from intercepting traffic, making stealing session IDs more difficult.
  • Don’t log in on open wireless networks. A public, unencrypted Wi-Fi network invites a malicious hacker to steal your data. So, it’s best not to use that.
  • Keep software updated with the latest security patches to prevent attackers from exploiting vulnerabilities to access users’ sessions.
  • Always prefer to use sites with HTTPS, as HTTPS means that the data your computer sends to the server is encrypted.
  • Don’t click on a link if you aren’t sure about the authenticity, as it might be a session hijacking attempt.
  • At the end of each session, log out. If you log out of your account, the session will terminate; you’ll also make the attacker log out, preventing him from hijacking the session.
  • Install antivirus and firewall software on your system because they can detect and remove viruses while providing a solid defense against malware attacks and, eventually, session hijacking.

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In a session hijacking attack, an attacker steals a user’s active session in order to gain unauthorized access to the website’s actions and information. With the help of that data, an attacker can perform various unlawful activities, such as transferring your money to his account, stealing your company’s sensitive data, and much more. So, rather than being sorry later, use the preventive measures outlined above.


Why does an attacker use a session hijacking attack?

An attacker uses a session hijacking attack to obtain unauthorized access to the web server by capturing a valid session token.

What methods are there to carry out au00a0session hijacking attack?

The following are some of the most common ways to carry out a session hijacking attack: Session sniffing Cross-site scripting (XSS) Brute Force attack Malware Session fixation Man-in-the-browser attack, etc.

What are some tools that can be used in a session hijacking attack?

Some of the tools that can be used for session hijacking attacks are: Burp Suite Ettercap OWASP ZAP BetterCAP sslstrip, etc.

What are the most common consequences of a session hijacking attack?

Identity theft and information theft are expected consequences of a session hijacking attack if carried out successfully.

How does a VPN protect against a session hijacking attack?

A VPN can hide your IP address, protecting you from session hijacking attacks and keeping your online activity private and secure.

How can you prevent a session hijacking attack?

Some of the ways to prevent session hijacking attacks are: Share session IDs with only trusted sources Use a VPN Donu2019t log in on open wireless networks Keep software updated Always prefer to use sites with HTTPS At the end of each session, log out Install antivirus and firewall softwareu00a0

About the Author
Anshuman Singh
Senior Executive - Content

Anshuman Singh is an accomplished content writer with over three years of experience specializing in cybersecurity, cloud computing, networking, and software testing. Known for his clear, concise, and informative wr... Read Full Bio