![]() ![]() Most applications store a session ID in a cookie, so attackers go after this cookie. Since a session identifies a user, if an application only uses a session ID to identify a user, an attacker can use just this session ID to perform actions on behalf of the user. The way an attacker would perform this attack depends on the target application, but any POST or GET request that uses only the session ID to verify the user would be vulnerable to session fixation. The final stage after the cookie is stolen is called session fixation. With this cookie in hand, the attacker can then perform actions on the application in the context of the user’s session. Using cross-site scripting and phishing emails, an attacker could trick a user into divulging their session cookie. ![]() Insecure Wi-Fi, malicious Wi-Fi hotspots, or a malicious user on the local network could intercept data with tools such as WireShark (among others) and obtain cookie session values when no encryption is used to transfer the cookie from the user browser to the server.Īn application layer attack primarily works with vulnerable GET requests. ![]() The first session attack involves man-in-the-middle (MitM) attacks, which puts some responsibility on the user (although some server and application security issues can contribute to the attack).īecause cookies are sent with every authenticated request, TCP hijacking is a concern if you do not have SSL/TLS certificates installed on your servers. This article covers the second type, because it’s primarily the responsibility of the developer to ensure that the session cookie is safe in the application layer. HTTP session hijacking at the application layer.TCP session hijacking at the network level.There are two types of session hijacking methods used in this attack: Every time the user makes a request to the application, this cookie is sent with the request. Notice that the HttpOnly cookie attribute is also set, which is one way to stop session hijacking from cross-site scripting, which we’ll cover soon. When you authenticate into a web application, you’re given a session cookie to identify every call to the application with an expiration date and time. Below is an example server response to set a cookie after authentication: What Exactly is a Web Session?īefore going into the details of the attack, the first step is understanding web sessions.įor every request the browser sends to your web application, a session cookie is sent with the request to identify the user. As you can probably imagine, this could be devastating for a user who would have no idea that their account is compromised and could not stop it from happening. Should an attacker gain access to a user session ID, the attacker can identify themselves as the user and perform transactions on the application as the user. Developers instead should generate new session IDs after several user actions such as authentication (or re-authentication), before important functions (e.g., withdrawing or transferring money) and after the user logs out.īecause a session cookie identifies a user, it’s important to keep this session ID and the session cookie protected from theft and incorporate session hijacking mitigation in your code. It’s this process that many developers leave open to vulnerabilities in an effort to make the authentication process more convenient for their users. When a user deauthenticates, however, it’s important for developers to destroy the session on the server instead of relying on the session to expire. The browser and application server determine when the session ends, but an application can use session restoring to keep cookies persistent indefinitely. As a developer, you must take necessary steps to protect session IDs and the cookies that contain session values. A session cookie is sent along with your user’s web requests to identify them on every authenticated call, including financial transactions or any other transfer of sensitive information. In most applications, the user session is stored in a cookie for reuse as the user makes calls back to the server in the application. A user session is a randomly generated alphanumeric value that identifies the user on the server. As a programmer, you will often work with user sessions. ![]()
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