How to Detect and Prevent Session Hijacking

Imagine leaving your car key at a public place, only to drop your keys when exiting the vehicle. Someone picks them up and drives away. They speed through a school zone and are caught on camera. Later, the car is used in a robbery. Now, you're not only missing your car but also wrongly implicated in criminal activities.

Session hijacking in cybersecurity is similar in nature but instead of stealing your car, an attacker takes over your browsing session. While it might seem less dramatic, the consequences are very real. An attacker can potentially drain your bank account, access your personal data, or perform malicious acts under your identity. In an era in which the web browser has become the primary application used nearly every day to access the cloud, session hijacking is a real problem. Just as car owners must be vigilant about auto theft, internet users need to take internet security seriously.

This article will provide a comprehensive look at session hijacking and why so many people are vulnerable to this type of attack. We'll cover the session hijacking definition, explore various methods used to steal web sessions, examine a session hijacking example, and most importantly, discuss prevention strategies.

What is Session Hijacking?

What is session hijacking in cybersecurity? Session hijacking occurs when an attacker takes control of an authenticated session between a user and a web application. The attacker essentially steals the session token or cookie that identifies the user to the server, allowing them to impersonate the legitimate user. Once the attacker acquires this token, they can potentially access the user's sensitive data or perform malicious actions using the victim's identity. Session hijacking is a real concern for multiple reasons:

• It can lead to theft of personal information, financial data, or other confidential data
• It can potentially damage the reputations of the impersonated users
• Users often have a hard time realizing that their session has been hijacked
• Can lead to violations of data protection regulations like GDPR or HIPAA

Session hijacking is not a new security phenomenon and has been known by other alternative names such as cookie hijacking or TCP Session Hijacking, which is an older term that highlights hijacking of TCP sessions. In some cases, session hijacking can be considered as a form of credential theft as well.

Another form of session hijacking is what is known as session side jacking. While the objective is the same for each type of attack, they differ in technique and approach:

1. Session Hijacking typically involves an attacker gaining control of a user's active session by stealing or guessing session tokens. The attacker can exploit these tokens to take over the session, often without the user's knowledge. This method doesn't always require access to the victim's network but instead focuses on capturing or manipulating session tokens.
2. Session Side-Jacking specifically refers to intercepting session cookies or tokens over unsecured networks, often through packet sniffing on public Wi-Fi or other unencrypted channels. Here, the attacker captures the data during transmission (especially HTTP cookies) to impersonate the user in that session. Side-jacking exploits unsecured connections, while hijacking can occur through token manipulation alone.

How Does Session Hijacking Work?

Once a user is logged on, a session key is generated. This key serves as a unique identifier for the user's session. This allows the server to recognize and maintain the user's authenticated state. This session key acts as a security token that the client sends whenever requested during the session. Compromising the session is typically the first objective of an attacker. While attack methodologies may vary, a typical hijacking session follows this basic script:

1. Attackers first choose a victim and look for weaknesses in their session management, such as predictable session IDs or insecure transmission of session tokens.
2. The monitoring process begins which may include packet sniffing tools to intercept network traffic and requests.
3. The session is intercepted using some type of technique such as Cross-site Scripting (XSS) attacks to steal cookies
4. Once the attacker has acquired the session ID and the legitimate user has authenticated with the service, the attacker can impersonate the user by applying the stolen session ID to their own browser.
5. Now the real objective begins as attackers access the victim's account to view personal information, perform transactions, steal credentials, or even change account settings. Attackers might also use browser extensions or scripts to keep the session active, avoiding automatic logouts or timeouts.

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Now let's examine some of the various techniques that threat actors commonly employ to attempt session hijacking during your web browsing activities.

• Session Sniffing: An attacker intercepts network traffic to capture session tokens. Attackers use packet sniffers to monitor data transmitted over a network, especially on unsecured Wi-Fi networks. They look for session cookies or tokens in the intercepted traffic, which they can then use to impersonate the legitimate user. This technique is a common method of session token hijacking, as it enables attackers to gain unauthorized access by exploiting intercepted session tokens.

• Cross-site Scripting (XSS): The Open Web Application Security Project (OWASP) lists Cross-Site Scripting (XSS) as one of the top web application security vulnerabilities. Here an attack injects malicious scripts into web pages viewed by other users. The page loads with injected malicious code, appearing legitimate to the user as it originates from a trusted server. This code, once executed, allows the attacker to capture the user's session ID.

• Man-in-the-Browser Attack: Unlike a man-in-the-middle attack that intercepts network traffic using some type of rogue device, this malware operates directly within the browser. In this case, an attack infects a user's computer with malware. Once installed, it allows the attacker to serve as a man in the middle the next time a user logs onto the computer. When a user accesses sensitive websites, like banking or e-commerce sites, the malware can alter transactions, capture login credentials, or redirect funds without the user's knowledge.

• Predictable Session Token IDs: These types of attacks are possible when a web application generates session IDs in a way that is easy for attackers to guess. A sequential numbering system or time stamps might be used. If attackers can predict the next session ID, they can potentially hijack that session and use it to gain unauthorized access to the user's data or privileges.

Types of Session Hijacking Attacks

There are multiple ways to implement a session hijacking attack. The following are some of the prevalent methodologies employed by attackers today.

• Active vs. Passive Hijacking: Session hijacking can be categorized into two main types: active and passive. Active hijacking involves the attacker intercepting the connection and taking control of the session, often forcibly disconnecting the legitimate user. In contrast, passive hijacking is a stealthier method where the attacker eavesdrops on the session without disrupting it, primarily to gather information. Active hijacking provides immediate control, while passive hijacking allows for prolonged, undetected surveillance.

• Session Sniffing: Attackers intercept network traffic to capture session tokens. In many cases they use the same tools such as Wireshark that network support technicians use to analyze network packets. This method can potentially compromise user accounts and data security, especially on unsecured networks.

• Cross-Site Scripting (XSS): XSS is carried out by injecting malicious scripts into web pages that are viewed by unsuspecting users. These scripts are then used to steal session cookies and send them to the attacker.

• Session Fixation: In this attack scenario, the perpetrator establishes a known session ID for a user prior to login, often by deceiving them into clicking a link with a preset session identifier. Once the user authenticates, they unknowingly activate this compromised session, allowing the unauthorized attacker to gain access to their account.

• Man-in-the-Middle vs. Man-in-the-Browser Attacks: Although similar in concept, these two attack techniques are different. MITM attacks intercept communication between two parties, while MITB attacks use malware installed on the user's device to manipulate browser sessions.

Let's take a moment to distinguish between session hijacking and session spoofing. As its name implies, session hijacking involves the attacker taking over an active, authenticated session by intercepting or stealing the session token. This allows them to then directly access the user's account or data. Session spoofing involves creating a fake session that appears legitimate to the server. In essence, the attacker attempts to trick the system into interpreting their session to be a valid authenticated user.

Real-World Examples of Session Hijacking

Here are some of the more renowned session hijacking incidents.

• Zoom-bombing: This attack was prevalent at the start of the Covid-19 pandemic when organizations quickly implemented Zoom meetings for their dispersed workforce. Attackers would hijack or disrupt active Zoom sessions by joining unsecured meetings that were shared publicly without sufficient security measures. The attackers often displayed offensive or disruptive content that resulted in interruptions and embarrassment. In the worst case, a data breach was possible.

• Mozilla Firefox "Firesheep" extension: Firesheep was a Firefox extension released in 2010 that demonstrated how easy it was to hijack sessions on unsecured Wi-Fi networks. The extension scanned open Wi-Fi networks for unencrypted HTTP sessions and captured session cookies. Once captured, perpetrators could log onto a website as the unsuspecting victim. This is one of the reasons why the industry moved HTTPS adaption that enforces encryption for better security.

• GitLab and Slack Vulnerabilities: GitLab experienced a session management vulnerability that exposed user session tokens, enabling attackers to impersonate users and access sensitive repositories. Slack's vulnerability allowed session hijacking through phishing and social engineering tactics. This granted the attackers unauthorized access to messages, files, and sensitive organizational data. These cases highlight the critical importance of robust session management in collaborative platforms.

The Risks and Consequences of Session Hijacking

Just as the opening automobile hijacking analogy included tangible risks, session hijacking in the digital realm can lead to severe consequences for users as well. These include:

• Possible identity theft as attackers can impersonate users and possibly gain access to personal accounts and information.

• Financial theft is a common objective as attackers attempt to conduct unauthorized transactions or access sensitive financial data using the captured session.

• Data breaches are a big concern for organizations as attackers can gain access to sensitive customer data or proprietary data.

• Denial of Service (DoS) attacks are a possibility too as multiple captured sessions can be used to mount attacks that overwhelm systems and cause service disruptions.

Other consequences can include the erosion of customer trust, reputational damage and a disruption to business operations. While some of these are less observable, they cumulatively have a negative effect on a company over time that affects market share and profits. The incidents may also cause significant disruptions to business operations indirectly as resources are diverted to address the breach and implement enhanced security measures.

How to Detect Session Hijacking

Just as there are multiple attack methodologies that attackers can take to hijack a browser session, there are multiple tools you can use to protect your organization against such attacks.

• A good place to start is an Intrusion Detection System (IDS). An IDS is designed to monitor network and system activities for malicious actions or policy violations. They can detect and identify patterns, and the signatures associated with known session hijacking tactics. A host-based IDS can detect anomalies in system behavior that might indicate a compromised session, such as unexpected privilege escalations or unusual file access patterns.

• Anomaly Detection Tools employ machine learning and statistical analysis to establish normal patterns for network traffic. IT and security personnel can be alerted whenever a session deviates from these norms. These tools go beyond the typical IDS to identify more subtle, behavior-based indicators that may evade traditional methods. In relation to session hijacking attacks, you are monitoring for any unusual account activity pertaining to login patterns. An example might be an account accessed from multiple locations within minutes could indicate a session takeover. In this instance, locations are identified by their IP address.

How to Prevent Session Hijacking

The key to keeping your organization secure from attack is a multilayered security strategy. You should also not just depend on tools alone but incorporate a multitude of measures to stop session hijacking and session side attacks.

• Use HTTPS everywhere across online environment. Emphasize the importance of SSL/TLS encryption on all your websites and web applications.

• To prevent session fixation, ensure that you regenerate all session IDs after each login. This will invalidate any pre-existing session ID that might have been compromised or preset by an attacker.

• Multifactor Authentication is an absolute must today. With MFA even if an attacker manages to obtain a valid session ID, they will still need additional authentication factors to gain access. MFA is also used to combat brute force attacks.

• Well-informed users form a strong first line of defense against such threats. Ongoing cybersecurity training for your users can educate your teams how to identify phishing scams and avoid them as they are commonly used to implement session hijacking attacks. They act as a shield between web applications and the internet, analyzing and filtering HTTP/HTTPS traffic to detect and block malicious activities.

• Limiting session duration may sound simple, but it can prove highly effective at reducing the window of opportunity for attackers. The premise is simple. By automatically terminating sessions after a period of inactivity, the timeframe during which an attacker can exploit a hijacked session is significantly shortened.

Response and Recovery After a Session Hijacking Attack

It is unrealistic to think that your organization will never fall victim to an attack. Below is a recommended course of action you should take in response to a session hijacking attack.

1. Terminate All Active Sessions. Immediately ending all active sessions across the system ensures that any potentially compromised sessions are immediately invalidated. With their captured sessions terminated, attackers cannot continue to operate.
2. Reset Session Token. Implement a system-wide reset of session tokens that requires all users to reauthenticate. This process creates new, secure session identifiers that will secure future sessions.
3. Prompt Users to Change Passwords. Implement password changes to ensure that any compromised password information cannot be used by the attacks to gain future unauthorized access.
4. Conduct a Thorough Investigation. A cyberattack of any kind should be seen as a learning experience. The two primary objectives are to learn the root cause and full extent of the session hijacking incident. Have an internal or external security team analyze all involved logs, network traffic, and system configurations to understand how the attack occurred. The findings can then be used to shore up your security efforts to thwart future similar attacks.
5. Update Security Protocols and Patch Vulnerabilities. By reviewing the investigative findings, your team will know what steps to take. These steps will most likely include updating your security protocols to address any weaknesses exploited by the attackers. It may also include the implementation of stronger encryption, enhanced network segmentation, and patching discovered vulnerabilities.

Long-Term Strategies for Securing Sessions

While you must be prepared for dealing with an active cyberattack, relying on a reactive "whack-a-mole" approach is not sustainable in the long run. Having a long-term strategy in place is critical to ensuring a secure enterprise. Any comprehensive cybersecurity strategy should include the following practices.

• Regular Security Audits: Conduct frequent security assessments to identify vulnerabilities within your systems. These audits should include a mixture of penetration testing and risk assessments of both internal and third-party components to ensure robust security measures are in place.

• Continuous Monitoring: Hackers don't have set hours. You never know when they may choose to attack, which is why 24/7 monitoring of your IT estate is so imperative. Monitoring includes tracking user behavior, analyzing traffic patterns, and employing advanced threat detection systems to identify potential breaches early.

• Training and Awareness Programs: Your users are on the front lines so make sure they have the knowledge they need to identify suspicious behavior and activities within their operating environments. Users are often the weakest link for any organization which is why they are so heavily targeted using phishing campaigns and session hijacking attacks. Regular awareness training will pay substantial dividends over the long run.

• Engagement with Cybersecurity Experts: Unless you are a cybersecurity firm, your organization can't be expected to be experts about every type of cyberattack. Be sure to bring in outside cybersecurity professionals to collaborate with to gain insights into best practices and emerging threats.

How Netwrix Can Help

Netwrix offers a suite of solutions designed to enhance cybersecurity defenses against sophisticated threats like session hijacking.

1. Netwrix Enterprise Auditor minimizes vulnerabilities by identifying risky conditions in your environment. It proactively detects and resolves security gaps, reducing your attack surface to keep sensitive data secure from unauthorized access and hijacking attempts.
2. Netwrix Endpoint Protector protects against data exfiltration attempts via USB devices, emails, browsers, and other channels. This layered protection helps prevent unauthorized data transfers that could follow a successful session hijacking.
3. Netwrix Threat Prevention provides real-time alerts for suspicious activity, such as unauthorized authentications and system changes that could signal an ongoing attack. This enables security teams to quickly investigate and stop malicious actions before they escalate.
4. Netwrix Password Secure enforces strong password policies to secure user accounts, a critical step in thwarting hijacking attempts.
5. Netwrix Ransomware Protection solution detects and disrupts ransomware activity early, stopping it from corrupting or locking your data - essential in safeguarding against attacks that could follow a session hijack.

Together, these tools support a proactive, unified defense to protect against threats like session hijacking.

Conclusion

Session hijacking remains a significant threat today. Like any cyber threat, it involves the exploitation of vulnerabilities. To effectively combat session hijacking, organizations must adopt a multi-faceted approach that incorporates effective response and remediation measures, as well as a long-term strategy to stay ahead of the evolving threat landscape. Implementing secure protocols, session management practices and strong encryption are good first steps. These measures need to backed up further however by additional measures that include MFA, continuous monitoring, regular security audits, user awareness training and prompt patching of vulnerabilities. In the end, a proactive security strategy is your best defense against session hijacking and other types of attacks.

FAQs

How can I tell if my session has been hijacked?

While there may not be obvious clues identify an active session hijacking attack isn't obvious, there are some telltale signs to look for. Indicators of an attack may include unexpected logouts or session expirations, unusual account activities or changes that you never initiated. You may also receive alerts from your account vendors about suspicious activity or notifications of logins from unfamiliar locations or IP addresses. Even something as simple as degraded performance on your session browsing device may be a valid indicator.

What is session hijacking in real life example?

Imagine logging into your online banking account while connected to a public Wi-Fi network at a coffee shop. If the network isn't secure, a nearby attacker could intercept the data packets exchanged between your device and the bank's servers. This attacker could capture the session token - a unique identifier your bank assigns to you while you're logged in - and use it to impersonate you.

Is session hijacking the same as phishing?

While they are not the same thing, phishing is often used in conjunction with a session hijacking attack. Phishing is a social engineering attack where attackers try to trick users into revealing sensitive information such as login credentials or credit card information. It involves the sending of fraudulent emails or fake websites that appear legitimate to deceive users. Session hijacking involves the takeover of an active, authenticated session between a user and a server. The attacker intercepts and uses the legitimate user's session token to gain unauthorized access to the user's account or data.

What are the best tools for detecting session hijacking?

While tools alone cannot guarantee complete security, a well-chosen set of proven security solutions can significantly enhance your organization's ability to detect and prevent session hijacking attempts. Your toolset should begin with the basics such as Intrusion Detection System (IDS) or Intrusion Protection System (IPS), web application firewalls, and packet sniffers. Network monitoring tools or log analysis tools that are intelligence based can help identify unusual patterns, anomalies or suspicious behavior that could indicate an attack. Access to penetration tools may also provide insight into how an attack may launch a session hijacking attack on your user base.

What is the best defense against session hijacking?

Implementing the principle of least privilege is one of the best defenses against session hijacking and other cyber threats, as it restricts an attacker's ability to conduct operations even if an account or system is compromised. A proactive strategy that incorporates regular security audits, continuous vulnerability scanning, and enhanced 24/7 monitoring will alert your teams to potential attacks in progress, allowing for immediate intervention. Timely patching is another measure that should be strictly enforced across any digital organization.