Glossary
Session Hijacking
When you log into a website, it gives you a special ticket (session token) so you don't have to log in again for every page. Session hijacking is when someone steals that ticket and uses it to pretend to be you. They get full access to your account without knowing your password.
What is Session Hijacking?
An attack where an attacker takes over a valid user session by stealing or predicting the session token, allowing them to impersonate the legitimate user without needing their password.
Why Should You Care?
Session hijacking bypasses the strongest passwords and multi-factor authentication once a user is logged in, giving attackers full account access to steal sensitive data, modify settings, or perform unauthorized transactions. For financial institutions and SaaS platforms handling customer PII, a single hijacked session can compromise compliance (SOC 2, PCI-DSS) and trigger costly breach notifications. Security teams must detect hijacked sessions in real time because the attacker appears as a legitimate user, making traditional perimeter defenses ineffective.
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Real-World Example
When attackers intercept session tokens over unencrypted WiFi networks (e.g., at airports or coffee shops), they can replay the token to access the victim's email, banking, or cloud accounts without the password. Browser extensions, malicious proxy tools, and network sniffing—especially on public networks—have enabled attackers to harvest sessions at scale, which is why HTTPS and secure cookie flags (HttpOnly, Secure, SameSite) are now mandatory security controls.
How to Protect Against Session Hijacking
- 1.
Use HTTPS everywhere on your website
- 2.
Set secure and HttpOnly flags on session cookies
- 3.
Regenerate session IDs after login
Related Terms
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