Understanding Session Hijacking: How to Keep Your Website Safe

As the admin of a WordPress site, it’s important to protect your users from session hijacking. This is a type of attack where a hacker steals a user’s session ID to gain unauthorized access to their account. 

Although session hijacking affects site visitors, your site may be used in these attacks. It is important to check your site for vulnerabilities that facilitate session hijacking attacks. 

In this article, we will explain exactly what the attack is, and how to prevent it on your site.

The worst part of session hijacking attacks is that users can be completely unaware that they are at risk. You want visitors to have a safe experience when visiting your site, so it is vital to scan for vulnerabilities that can lead to session hijacking attacks. MalCare is a sure-fire way to protect against these attacks and safeguard your visitors.

What is session hijacking?

Session hijacking, also known as an impersonation attack, is when an unauthorized user takes control of a user’s session on a website or application.

Sessions are created on the server for each user and are assigned a unique ID. Attackers are mostly after session IDs to gain access to systems, but the session data itself can also contain sensitive personal information that can be used for malicious purposes.

The attacker intercepts the session ID and uses it to gain access to the user’s active session. This allows them to steal the user’s data or perform unauthorized actions on a site like yours, for example. 

Session hijacking attack can have severe consequences, such as unauthorized access to sensitive data, financial loss, and damage to the reputation of the affected user or organization. 

How do hackers hijack sessions?

There are several techniques used to carry out session hijacking attacks. By understanding these techniques, you can identify vulnerabilities and implement the security measures we’ve talked about in a later section. 

1. Session fixation

One of the techniques used for session hijacking is session fixation. This involves forcing the user’s session ID to a known value that can be later used by the attacker to hijack the session. During a session fixation attack, the attacker tricks the user into using a session ID specified by the attacker, usually by sending the user a link containing the ID.

Session fixation is a different mechanism for session hijacking because it doesn’t involve trying to guess a valid session ID (prediction) or stealing an existing session ID (capture). Instead, the attacker sets a known session ID before the user logs in, and then hijacks the session after the user logs in using the same session ID.

By using session fixation, attackers can bypass authentication mechanisms and gain access to the victim’s account or sensitive information. To prevent session fixation attacks, developers should implement countermeasures such as randomizing session IDs, regenerating session IDs on login, and verifying the validity of session IDs during each request.

2. Cross-site scripting

Cross-site scripting attacks involve injecting malicious code into a website that can steal the user’s session cookies or other personal data. Session cookies store user session IDs, which can be used by an attacker to hijack the user’s session.

During a cross-site scripting attack, the attacker injects malicious code into a vulnerable website, such as a comment section or a search field. When a user visits the infected website, the malicious code executes on the user’s browser, allowing the attacker to steal the user’s session cookies.

3. Sidejacking/Man-in-the-middle attack 

A third technique used for session hijacking is session sidejacking, which is a type of man-in-the-middle (MITM) attack. During a MITM attack, the attacker intercepts the communication between the user’s browser and the website’s server and steals the session cookies.

In a session sidejacking attack, the attacker is able to steal session cookies through unsecured Wi-Fi networks. When a user logs into a website using an unsecured Wi-Fi network, the attacker can intercept the user’s communication with the website and steal their session cookies. With these cookies, the attacker can hijack the user’s session and gain access to their account or sensitive information.

4. Session prediction

Session prediction involves guessing a valid session ID by analyzing the pattern and structure of the session IDs that are generated by a website’s server.

Session prediction is similar to brute force attacks, which involve trying multiple combinations of session IDs until the correct one is found. However, session prediction is more targeted and relies on the attacker’s ability to analyze and predict the session ID structure used by the website.

5. Exposed session data

The final technique used for session hijacking is the exposure of session data. This is usually rare because session information resides on a server with minimal public exposure.

However, in some cases, it is possible for hackers to read data as it is being transmitted back and forth between the user’s browser and the website’s server. This is known as packet sniffing, and it can result in the exposure of session data, including session IDs.

How to recover from a session-hijacking attack?

If you’ve experienced a session hijacking attack on your website, don’t panic. There are several quick and effective steps you can take to recover from it.

Scan for malware and remove it: It is crucial to check your website for any malicious code that may have been inserted during the attack. There are several malware scanners available that can help you identify and remove malicious code from the WordPress site. But we highly recommend MalCare because it is quick, reliable and very easy to use. 

Force log out all sessions: Once you’ve identified the attack, log out all users from your website. This will end all active sessions and prevent the attacker from accessing any further information.

Change all passwords: It’s important to change all passwords associated with your website, including user passwords, cPanel, database, and any other relevant passwords. Additionally, changing salts and security keys is recommended as it will invalidate all current sessions and force log out users.

Update all plugins and themes: Outdated plugins and themes can often have vulnerabilities that can be exploited by attackers. Ensure that all plugins and themes on your website are up to date to prevent any further security issues.

How to prevent session hijacking attacks?

Now that you’ve addressed a session hijacking attack on your website, it’s crucial to take preventive measures to ensure that it doesn’t happen again. In this section, we’ll cover some effective strategies to help you prevent session hijacking attacks and keep your WordPress site secure.

Install a firewall: A website application firewall helps prevent session hijacking attacks by blocking malicious traffic and filtering out malicious requests that attempt to exploit vulnerabilities in the website’s code.

We recommend MalCare, as it is the best firewall for WordPress sites. It monitors incoming traffic and analyzes it for suspicious behavior or patterns that are associated with session hijacking attacks. MalCare also enforces security policies and rules that are designed to prevent session hijacking, such as blocking requests that contain suspicious session IDs or blocking attempts to access sensitive resources without proper authentication. 

Use SSL: Secure Sockets Layer or SSL is a protocol that provides secure communication over the internet. Using SSL can help prevent session hijacking by encrypting the communication between the user’s browser and your website, making it difficult for attackers to intercept and steal session cookies.

Use 2FA: Two-factor authentication (2FA) adds an additional layer of security to your website by requiring users to provide a second factor, such as a code sent to their mobile device, in addition to their password. This can prevent attackers from accessing user accounts even if they have managed to steal login data from session cookies.

Strong password policies: Implementing strong password policies can help prevent session hijacking by ensuring that users use strong and unique passwords. So if a hacker is able to get login credentials for one account, they cannot use it for accounts on other services or websites. 

Regularly update WordPress, themes, and plugins: Outdated software can have XSS vulnerabilities that can be exploited by attackers to hijack sessions. Ensure that your website’s WordPress core, themes, and plugins are up to date to prevent any security issues.

Use an activity log: An activity log can help monitor for suspicious activity on your site, such as failed login attempts, unauthorized access attempts, or unusual user behavior. This can help detect hijacked user accounts early and prevent them from causing damage.

It’s important to note that although browser vulnerabilities that allow session hijacking have mostly been eradicated, it’s still important to use the latest versions of browsers to ensure the best possible security. By implementing these measures, you can prevent session hijacking attacks and keep your website secure.

Why is session hijacking dangerous?

Session hijacking is a severe threat to website security and can cause irreparable damage to your users and your website. What can a hacker do when they hijack a session? Why is it dangerous?

Unauthorized access to user information: When hackers hijack a session, they can access the user’s account information, such as their login credentials, personal data, and transaction history. This can be used for identity theft, financial fraud, or other malicious activities.

Loss of sensitive data: Attackers can steal sensitive data, such as credit card information, personal data, or confidential business information, by hijacking a session. This can lead to significant damage to the user and your website’s reputation, as well as legal and financial consequences.

Possible fraud transactions: Session hijacking allows attackers to access the user’s account and make fraudulent purchases or transactions on their behalf. This can result in financial losses and reputational damage for the user and your website.

Hard to identify: Session hijacking poses a significant threat owing to its inconspicuous nature, making it arduous for users to identify. As the hacker can manipulate the user’s account without displaying any evidence of infiltration, the user may remain oblivious to the hijacking of their session.

What not to do?

WordPress deploys cookies, rather than transparent session IDs, for its session management. Consequently, the session IDs are not transmitted as a URL parameter. 

While you might encounter recommendations to modify the .htaccess or php.ini file by adding the line “php_flag session.use_trans_sid off,” there’s no need to do so, as this instruction is solely intended for transparent session IDs.

Wrapping up

Session hijacking attacks are a serious threat to the security of a website and more so to its users, particularly due to the difficulty in detecting it. 

However, the good news is that it is a fixable issue. As we have seen, implementing cookies instead of transparent session IDs can significantly mitigate the risks. WordPress does this by default, so you are safe in that respect. 

To protect your site and users from becoming victims to a session hijacking attack, install MalCare, a reliable WordPress security plugin. MalCare can not only help you detect and remove malware but also prevent future attacks with an advanced WordPress firewall.


What is an example of session hijacking?

An example of session hijacking is when a hacker takes control of a user’s active session and gains unauthorized access to the user’s account or data.

What is session hijacking and its types?

Session hijacking is a type of web attack where an attacker takes over a user’s active session to gain unauthorized access. The primary types of session hijacking are session fixation, session capture, session prediction, and session sidejacking.

Which attack is based on session hijacking?

Session hijacking is a type of web attack and is the basis of several other attacks, including cross-site scripting attack (XSS) and cross-site request forgery (CSRF).

How do attackers attack in session hijacking?

Attackers use various methods to launch a session hijacking attack, including session sniffing, session fixation, and man-in-the-middle attacks.

How is session hijacking prevented?

Session hijacking can be prevented by using secure session management techniques, such as deploying secure cookies and implementing Transport Layer Security (TLS) protocols.

Does HTTPS prevent session hijacking?

HTTPS can help prevent session hijacking attacks by encrypting the data exchanged between the client and the server, thus making it difficult for attackers to intercept and steal the session ID.

What is the solution to a session hijacking attack?

The solution to a session hijacking attack involves terminating the attacker’s active session, resetting the session ID, and implementing robust security measures to prevent future attacks. For WordPress sites, this means installing a security plugin with an advanced firewall, and making sure all the plugins and themes are updated. 

Can PHP sessions be hacked?

PHP sessions can be vulnerable to session hijacking attacks if not managed correctly. However, implementing secure session management practices can help prevent such attacks.

The post Understanding Session Hijacking: How to Keep Your Website Safe appeared first on MalCare.

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