Session Hijacking Explained: The Cloud Security Threat Nobody Is Talking About

SpyCloud’s CIO, Trevor Hilligos said, “Attackers are no longer focused on stealing credentials. Their target is authentication permissions like API keys and session tokens, which enable them to execute attacks across the cloud and business environments.” In the report shared on CSO Online, SpyCloud recaptured over 8 billion stolen session artifacts and cookies exposed to malware. A sign of increased attention to session jacking tactics that bypass passwords and multi-factor authentication. Imagine signing on to your business accounts only to find out someone else has taken control over them without your knowledge. That’s what session hijacking or cookie jacking is. It happens when a threat actor steals a unique user ID aka session token that browsers or apps authenticate once you log in. What happens when an attacker has your session tokens? They impersonate you to gain unauthorized permissions to sensitive data without the need for passwords. In this post, we’ll dive deeper into how session hijacking is executed and ways to prevent it to help you get smarter with cloud security.  

Hijacking Tactics  

Anytime you sign in to a platform or browser, the server creates a session ID, which is stored in cookies to keep you signed in. While these IDs eliminate multiple re-authentication requests, they create a vulnerability for hackers to exploit. Since your ID is already verified, an attacker can hijack it through session sniffing, for instance. Let’s say you’re using an unsecured public Wi-Fi. A criminal on the other side might be sniffing or tracking your network to extract valid sessions. If successful to intercept an unencrypted network, they take over your browsing activity.

Session cookies can also be stolen or hijacked through cross-site scripting or XSS. Hackers simply inject malicious scripts into sites or websites users trust. When activated, these scripts collect session tokens and send them back to the threat actor. Other methods of session hijacking include man-in-the-middle attacks or MITM, session fixation, and predictable session attacks. During a MITM attack, attackers block communication between the user’s server and browser. Then capture token IDs in transit and use them to hijack browsing activities.

When an attacker executes session fixation, they create a new authentication ID and trick a user into using it by sending them a pre-set session ID via email. Once the victim enters the fixed or ‘new’ ID, the attacker uses it to access accounts. Sometimes activity IDs generated by servers are not random, meaning criminals can guess or predict a user’s identity and apply brute force to get into their accounts.  

Effective Session Security Measures

Like other cyberattacks, session theft results in identity theft, financial and reputational damage, increased risk of denial of service attacks, and malware infections. Prevention is key to avoiding these impacts. Start by enforcing HTTPS to encrypt all data shared between your server and browsers. Even if cybercriminals are session sniffing or planning a man-in-the-middle attack, they can’t read your session IDs because the TLS or transport layer service HTTPS uses makes data unreadable. Also, secure cookies by setting an HttpOnly cookie policy. Doing so ensures all cookies are transmitted through https, to prevent cookie theft.

Besides activating HTTPS everywhere, monitor web or cloud-based browsing sessions in real-time to enhance data protection from infostealers. Do this using device fingerprinting, where you bind a session token to a device, and if the gadget’s ID changes instantly, you terminate the session. Use advanced malware detection tools like endpoint detection and response, infostealer log monitoring, and AI-assisted SOCs as well to safeguard sensitive data. 24/7 AI-centric SOC experts analyze user behavior continuously and monitor traffic to detect and stop anomalies that signal active hijacking of sessions. Be sure to patch cross-site scripting weaknesses and regenerate random tokens after successful logins.  

Identifying Session Theft  

Threat actors are not guessing login details or passwords that could trigger login failure alerts. They’re using cookies or sessions that have been permitted, so security systems consider their activities as normal. Without notifications of possible attacks on sessions, it’s difficult to tell when a hacker is sniffing or executing an XSS. But there are things you can do like reviewing active sessions. Check for unfamiliar devices used to access your accounts and unexpected IP addresses or locations? If so, you’re not safe online. And your response should be signing out from the app or browser on all devices, changing passwords, and running a malware scan. If you can view your network logs, look out for active sessions from different geographical regions and browser changes mid-session. Don’t forget to review purchase history or emails sent without your authorization.

People don’t talk about it enough, but session hijacking is a growing threat. And it’s powered by increased adoption of SaaS applications, remote work, and an expanding infostealer marketplace. Plus, many organizations focus on safeguarding the login or front door, not the activities that follow after authentication. To mitigate this cyber risk, organizations need to secure cookies and encrypt data in transit with HTTPs, monitor sessions continuously, and implement zero trust to get rid of trust after authentication.