![]() Regenerating a session ID will not protect against a recently stolen session ID, but it will keep session IDs fresh and force an attacker to use a recent session ID. Any existing session information is maintained, it is only the identifier which gets refreshed. It is most important to regenerate the session ID after a successful login. Regenerating a session ID invalidates any previously stolen session IDs. = time ()) } ?>Ī strong defense against session hijacking is to regenerate session identifiers periodically and at key points. If the test fails, then the session could be regenerated (see below) or the user could be required to log in again. This is an example in PHP showing how to determine if a user's last login was more than one day ago. In addition to or instead of sweeping, code can check for old sessions whenever a new request is received. This process is called "session sweeping". A script is then written which will run at timed intervals (every midnight, every four hours, etc.) and which will remove stale sessions. Last activity can be tracked by inspecting the "last modified" timestamp of a session file, or by automatically updating a "last modified" field for sessions stored in a database table. ![]() The most common technique is to track either the user's last activity or their last login (or both). Fewer sessions in existence means fewer sessions which can be hijacked. It is also a best practice to expire and remove old session files regularly. A hijacker with possession of a logged-out session can simply wait for the session to be logged-in again. Often, the user's authentication status is removed but the session itself is retained for re-use. ![]() HttpOnly cookies prevent an attacker from discovering the stored session ID using at XSS attack.Īnother good prevention is to fully destroy sessions whenever a user logs out. This technique is one of the standard preventions for Cross-Site Scripting (XSS). The first prevention is to use HttpOnly cookies for setting session IDs. But these broadcasts are also visible to any other device in the room, including an eavesdropping attacker. When communicating over WiFi, a laptop or mobile device broadcasts a request "into the room" and the WiFi device in the room receives the signal. It is especially easy for an attacker to eavesdrop by inspecting all traffic on an open and unencrypted wireless network, such as the free WiFi offered at coffee shops and other businesses. Remember, the session ID is sent with every request to the server. In transit, the session ID can be observed by eavesdropping on the network traffic. In storage, the session ID can be stolen from the user's browser cookies, often via Cross-Site Scripting (XSS). The session ID is vulnerable in storage and in transit. Session hijacking requires an attacker to determine the session ID. They can impersonate the user and send communications to friends and coworkers as a spear phishing attack (see Social Engineering). They can change the account password, which will lock out the real user. ![]() They can view and edit personal information. A hijacker with a logged-in session can perform any action which the user could perform. ![]() The session is often used to maintain the user's logged-in state or other authorization to perform access-restricted actions. An attacker can send a request with the user's session ID and assume for themselves any previous state set in the session. The server must assume that any request including a user's session ID must be originating from the user's browser. But even worse, the attacker can impersonate the user. (Every request to the server will send visible cookie data.) Discovering the session ID provides an attacker access to all session data. This session ID is vulnerable to theft because cookies are visible in storage and in transit. However, to identify the user and give them access to the session data, it is necessary to set a session reference identifier ("session ID") in a browser cookie. Sessions are more secure than putting user data into browser cookies because the data being stored never leaves the server. Sessions store information about a user on the server-side, usually either in a file or a database. Session hijacking is an attack where the attacker steals a user's active session with a website to gain unauthorized access to actions and information on that website. ![]()
0 Comments
Leave a Reply. |