Session hijacking is a common type of attack that exploits the way web applications manage user authentication and authorization. In this article, you will learn how session hijacking works, what are the main techniques used by attackers, and how to prevent or mitigate this threat.
A session is a temporary and unique connection between a client and a server, usually established by a web application to identify and authorize a user. A session is typically created when a user logs in with a username and password, and is terminated when the user logs out or after a period of inactivity. A session is usually associated with a session identifier (SID), which is a random string of characters that is stored in a cookie, a hidden form field, or a URL parameter. The SID is sent by the client to the server with each request, and the server uses it to verify the user's identity and access rights.
Session hijacking is a cyber attack where an attacker steals a user's session ID to impersonate them. They intercept the session ID through methods like packet sniffing, XSS, or MITM attacks. With control over the session, they access the user's account and perform unauthorized actions, potentially leading to data breaches and financial losses. Mitigation involves secure session management and user vigilance.
Session hijacking attacks occur when an attacker intercepts and takes control of an ongoing session between a user and a legitimate service. This is often achieved by exploiting vulnerabilities in the session management mechanism, allowing the attacker to steal session identifiers or cookies. With these stolen credentials, the attacker can masquerade as the legitimate user, gaining unauthorized access to sensitive information or performing malicious actions within the session. Various techniques such as session fixation, session sidejacking, and man-in-the-middle attacks can be employed to execute session hijacking, posing significant security risks to users and organizations.
Las cookies cuando no están bien configuradas pueden ser susceptibles de ser robadas y utilizadas por actores maliciosos. Una buena configuración es esencial. Es posible secuestrar el inicio de sesión mediante peticiones suplantando la identidad del usuario legítimo. ésto no da control sobre la sesión y cualquier otra acción que se pueda realizar con cookies. Por eso es fundamental hacer un Pentesting de una aplicación web y detectar que acciones se pueden o no hacer con cookies.
Session hijacking is the process of stealing or manipulating a valid SID from another user to impersonate them and access their resources or privileges on the web application. Attackers can obtain or modify the SID in different ways, such as sniffing network traffic between the client and server with tools like Wireshark or tcpdump, predicting SIDs by exploiting a weak algorithm with Burp Suite or THC-Hydra, fixating a predefined SID for the victim by sending a malicious link, email, or script, and hijacking an active session from the victim by using tools like Ettercap or ARPspoof, or exploiting a cross-site scripting (XSS) or cross-site request forgery (CSRF) vulnerability. Reporting and documenting the incident is essential for communicating the status, findings, and actions of the incident response team to stakeholders.
Session hijacking can have serious consequences for both the users and the web applications that are targeted by the attack. Depending on the type and level of access that the attacker gains, they may be able to steal sensitive or confidential information, like personal data, credit card details, passwords, or tokens. Additionally, they could perform unauthorized actions, like transferring funds, changing settings, uploading files, or deleting data. Furthermore, they could escalate privileges to gain administrative rights, access restricted areas, or bypass security controls. Finally, they could compromise other users or systems by spreading malware, phishing, or launching further attacks.
Session hijacking can be prevented or mitigated by implementing various security measures on both the client and the server side. To protect the network communication and the SID from being intercepted or modified, use secure and encrypted protocols such as HTTPS, SSL, or TLS. Generate the SID using strong and random algorithms, such as SHA-256 or UUID, to avoid predictable or sequential patterns. Use short and limited session durations, such as 15 minutes or 30 minutes, and expire the SID after each logout or inactivity. Securely store the session data, such as server-side sessions or encrypted cookies, and avoid exposing the SID in the URL or browser history. Additionally, validate and verify each session request by checking the IP address, user agent, or timestamp, and reject any request that does not match the expected criteria. Furthermore, regenerate and renew the session by changing the SID after each login or sensitive action, and invalidate the old SID to prevent reuse. Finally, protect and defend against hijacking by implementing anti-CSRF tokens, HTTP-only cookies, or same-site attributes to prevent XSS or CSRF attacks that can manipulate or hijack the session.
1. Implement a mechanism to check the validity of the keys. It can be validated for expired keys, duplicated keys and very old keys 2. Never send or receive session IDs/keys through POST/GET requests 3. Always use SSL and HTTPS for login and session traffic 4. Always set the HTTP header Set-Cookie to HttpOnly. This prevents XSS attacks 5. To prevent Session fixation, regenerate the session periodically. Keeping small expirations is always a good practice 6. Regenerate the session during sensitive data access or update. For example, Re-authenticate the users during payments, password change 7. Use well-known packages/libraries for generating session IDs. Easier the id, the more vulnerable 8. Logging out when needed.
Session hijacking can be detected by monitoring and analyzing the session activity and behavior on the web application. Unusual or unexpected requests, inconsistent or mismatched parameters, multiple or concurrent sessions, and invalid or expired sessions are all indicators that can alert the users or the administrators of a potential hijacking. For instance, accessing resources or performing actions that are not typical or authorized for the user, having different IP addresses, user agents, or timestamps for the same SID or user, having more than one active session or user for the same SID or account, and having requests with SIDs that are not recognized or have been terminated by the server can all be signs of a session hijacking.