Session management: What it is and why your security depends on it
Tags: security, authentication, jamstack, nextjs
Published: 2021-09-20 22:52:57

Constantly having to log back in to your online accounts is a frequent annoyance - but this irritating problem stems from an inefficient solution to a genuine security concern.

Web applications need to make sure that your accounts are safe from hackers, and some handle that by requiring frequent re-authentication. Still, that's not the best solution. Proper session management can help apps like yours keep users safe *without *needing to constantly log back in.

Below, we'll cover the fundamentals of session management, what's required to implement it, and how it can help you keep your users safe without creating a frustrating user experience.



What is session management?
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[Session management](https://www.packetlabs.net/session-management/) is the process of facilitating private interactions between users and web applications. It specifically refers to managing different "sessions," or periods when the user is logged in and active in the application. The session management process lets users access their unique and potentially sensitive information securely without letting others get into their account, without forcing users to constantly re-authenticate.

Session management can take two forms: short-lived and long-lived. Short-lived sessions last only as long as the user remains in the application. Every time they leave the app, they need to re-authenticate to get back in.

Long-lived sessions keep the user logged in to the app even if they leave. These sessions store session IDs on the user's device, allowing them to reopen the app and start using it without needing to re-authenticate.

Long-lived sessions typically offer the best user experience, since they let people get into their accounts with no hassle. But this approach also has drawbacks. Anyone who accesses the device can also access that account as long as the session is still active, which is a security risk. For apps that contain sensitive information, short-lived sessions may make the user experience slightly more complicated, but will be more secure.

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The elements of session management implementation
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Proper session management implementation involves three functions: creating session IDs, storing session cookies or tokens, and enforcing session expiry dates.

Here's what that means:

__Session IDs__

When the user first logs into the website or app, the server creates a unique session ID associated with the authenticated user. However, with each new request, the server still needs a way of identifying if the request came from that authenticated user without needing re-authentication. Which is where cookies or [JWT](https://en.wikipedia.org/wiki/JSON_Web_Token) tokens come in.

__Session cookies vs. tokens__

When the server creates a unique session ID, it also creates a cookie that is stored in the user's browser. The information contained in that cookie is sent along with each new request so the server understands it comes from the same authenticated user.

Session cookies are most commonly used with websites or web-based platforms. When it comes to modern web applications, a JSON Web Token, or JWT, is used instead.

When the user logs on with the right credentials, a JWT is created instead of a session ID and sends it to the user. The JWT is stored in local storage and the header of the token is sent with every new request.

This means that the user's state is not stored on the server, but inside the token, making this option more scalable and more useful for mobile device authentication.

__Session expiry__

Sessions are temporary states and expire under certain circumstances, such as the mobile app being closed, a set period of inactivity, or a maximum session duration that cannot be exceeded. Long-lived sessions may expire when the user hasn't interacted with the app in a certain number of days or weeks. The cookie or token storing the session ID should automatically delete itself at the end of those periods.



Security concerns addressed by well implemented session management
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The purpose of session management is to help keep user data secure. Without appropriate session management, you can run into several security problems, putting your users at risk. Common vulnerabilities caused by a lack of or poorly implemented session management include:

‌__Session hijacking__

The cookies that you use to store session IDs need to be truly secure. Insecure session cookies are easy for hackers to predict or to use for brute-force attacks. If a hacker can spoof your users' session IDs, they can impersonate users and take over their accounts. This is known as session hijacking, and it can lead to the loss of sensitive information connected to the account.

‌__Session fixation__

If a specific session token can be used across platforms and without proper expiry protocols, it can be "fixated" by hackers. Essentially, the hacker tricks a user into logging in with a specific session ID, often by adding to the session ID in the URL argument, and then uses those credentials to log in to the user's account.

__Session resources__

Session management systems should beare resource-light, so that attacks, such as denial of service (DDoS) that flood the system with new session requests, don't consume huge amounts of resources.

‌__Anomaly detection__

Every application runs the risk of hacking attempts. If your session management tool doesn't have a way to detect abnormal patterns like brute force session ID guessing or DDoS attacks, you're more likely to fall victim to these attacks.

_‌_Session expiry unset or too long__

Session expiration has two potential problems. If you don't set the timeout period, many programs may leave the cookie or token on the device forever, leaving the account vulnerable to anyone else with the device. Also, a set timeout period that's too long has the same issue.

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Stay secure with session management
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‌Proper session management addresses all these concerns. It keeps your users and accounts safe by providing secure cookies or tokens, setting appropriate protocols and timeouts, and implementing anomaly detection.‌

Session management is a fundamental part of running a secure, trustworthy web application. By keeping a handle on your users' sessions, you can help them avoid the hassle of constant re-authentication without putting them at risk.

You can address all your session management needs by implementing a [user management](https://clerk.dev/) service, or you can write your own. Either way, your users will thank you for protecting them without making their lives more difficult.