Session Hijacking

What Does Session Hijacking Mean?

Session hijacking occurs when a session token is sent to a client browser from the Web server following the successful authentication of a client logon. A session hijacking attack works when it compromises the token by either confiscating or guessing what an authentic token session will be, thus acquiring unauthorized access to the Web server. This can result in session sniffing, man-in-the-middle or man-in-the-browser attacks, Trojans, or even implementation of malicious JavaScript codes.


Web developers are especially wary of session hijacking because the HTTP cookies that are used to sustain a website session can be bootlegged by an attacker.

Techopedia Explains Session Hijacking

In the early days, HTTP protocol didn’t support cookies and therefore Web servers and browsers did not contain HTTP protocol. The evolution of session hijacking began in 2000 when HTTP 1.0 servers were implemented. HTTP 1.1 has been modified and modernized to support super cookies which have resulted in Web servers and Web browsers becoming more vulnerable to session hijacking.

Web developers can enlist certain techniques to help avoid session hijacking of their sites, including encryption methods and using long, random numbers for the session keys. Other solutions are to change cookie value requests and implement session regenerations after logins. Firesheep, a Firefox extension, has enabled public user session hijacking attacks by permitting access to personal cookies. Social network websites such as Twitter and Facebook are also vulnerable when users add them to their preferences.


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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…