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What is Session Hijacking and How To Prevent It?

Session Hijacking

When a Session is a time when you are on the internet, Session hijacking means an attack over your internet session and the most common example one can give here is that, when you are using internet banking to check your bills or to do some transaction, an attacker can take over your internet session and hijack it. Session hijacking is usually done using web applications or browser sessions. A session hijacker can get complete access to your session and can do anything you could do on that website.

Types of Session Hijacking Attacks

  • Brute attack – In this type of Brute attack session hijacking, the attacker guesses your session ID and gains access. This usually happens when the website has the easy-to-guess session keys.

  • Malicious links – The attackers send you the Malicious links via emails that install the malware on your machine. This malware then shares your session cookie with the attackers letting them hijack your session.

  • Cross-site scripting – Here the attacker uses the weak security spots in a website or the server and injects their own scripts into the webpage. These custom scripts then make your browser reveal the session key and the attackers take over your session.

  • Session side jacking – In this hijack, the cybercriminals try to access your network traffic. An unsecured Wi-Fi makes it easier for attackers to intrude. They keep monitoring your internet session and attack as soon as they get your session cookie through your network.

  • Session fixing – Here the attackers create and send you a new session ID with a login link, via email. They trick you to start a session using that link and as soon as you click and login using that link, they can hijack your session.

How is a Session hijacked?

Attackers have a number of options to hijack a user’s session, depending on the attacker’s position and vector. Here are some of the ways a session can be hijacked:

  • Cross-site scripting (XSS): Attackers exploit vulnerabilities within servers or applications to inject client-side Java scripts into the users’ web pages, causing your browser to execute arbitrary code when it loads a compromised page. If the server doesn’t set the HTTPOnly in session cookies, injected scripts can gain access to your session key, providing attackers with the necessary information for session hijacking.

  • Session side jacking: By using packet sniffing, an attacker can monitor the traffic within the network and intercept the user's session cookies after they have authenticated it. If the website takes the cheap route of using SSL/TLS encryption for its login pages only, the attacker can use the session key they have derived from packet sniffing to hijack the user's session and impersonate them to perform actions in the web application. This can usually happen in case of an unsecured WiFi Hotspot in order to gain access to the network, monitor the traffic and set up their own access points to perform the attack.

  • Session fixation: Attackers supply a session key and spoof the user into accessing a vulnerable server.

How to Prevent Session Hijacking

In order to protect yourself from being hijacked while in a session, you need to strengthen the mechanisms in web applications. This can be done through communication and session management. Here are a few ways you can reduce the risk of session hijacking:

  • HTTPS: The use of HTTPS ensures that there is SSL/TLS encryption throughout the session traffic. Attackers will be unable to intercept the plaintext session ID, even if the victim’s traffic was monitored. It is advised to use HSTS (HTTP Strict Transport Security) to guarantee complete encryption.

  • HTTPOnly: Setting up an HTTPOnly attribute prevents access to the stored cookies from the client-side scripts. This can prevent attackers from deploying XSS attacks that rely on injecting Java Scripts in the browser.

  • System Updates: Install reputable antivirus software which can easily detect viruses and protect you from any type of malware (including the malware attackers use to perform session hijacking). Keep your systems up to date by setting up automatic updates on all your devices.

  • Session Management: In order to offer sufficient security, website operators can incorporate web frameworks, instead of inventing their own session management systems.

  • Session Key: It is advised to regenerate session keys after their initial authentication. This renders the session ID extracted by attackers useless as the ID changes immediately after authentication.

  • Identity Verification: Perform additional identity verification from the user beyond the session key. This includes checking the user's usual IP address or application usage patterns.

  • Public Hotspot: Avoid using public Wifi to protect the integrity of your sessions and opt for secure wireless networks.

  • VPN: Use a Virtual Private Network (VPN) to stay safe from session hijackers. A VPN masks your IP and keeps your session protected by creating a “private tunnel” through which all your online activities will be encrypted.

  • Phishing Scam: Avoiding falling for phishing attacks. Only click on links in an email that you have verified to have been sent from a legitimate sender.

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