Security of access tokens in the chat API: JWT and expiration

Why This Matters

Access tokens in the chat API aren’t just an abstract technical detail. They are the keys to all your sessions, chat histories, media files, and payment data — all at once. A single intercepted JWT token gives an attacker full access to your account — even if you’re sure you logged out a long time ago.

Here’s where the main trap lies: HTTPS protects data in transit, but it doesn’t protect the token that’s already stored in the browser. A malicious extension or script on the page can read it directly. Public Wi-Fi adds yet another attack vector. Without proper expiration, a token can remain valid for hours or even days — and during that entire time, it’s open to being exploited by others. Automatic expiration works like a timer lock: even a stolen token quickly becomes useless.

Risks and Dangers

The theft of API access tokens from chat platforms happens quickly and, as a rule, goes unnoticed by the user. Let’s examine specific attack vectors.

Setting the JWT token’s lifetime too long is the most common mistake. The token remains valid for 24 hours instead of 15 minutes, giving an attacker time to exploit it. The next risk is the absence of the “HTTP Only” and “Secure” flags on cookies: the token becomes accessible to JavaScript and is transmitted over unsecured connections. An XSS attack injects a malicious script directly into the page and steals the token from the browser without any notification. Finally, public Wi-Fi networks without a VPN allow traffic to be intercepted at the network level.

It’s also worth mentioning the illusion of security: the token itself isn’t secure — it’s secured by configuration. Without HTTP Only, Secure, and a reasonable expiration time, the door to an attack remains open, even if the connection is encrypted.

How to Set Up Protection Correctly

Below are specific steps for browser-based chat applications. Mobile clients use similar logic but store tokens in the OS’s secure storage rather than in cookies.

Step 1. Check the security section in the service settings: make sure the HTTP Only and Secure flags are enabled for cookies containing tokens. You can verify this in the browser’s DevTools (Application tab → Cookies): the HttpOnly and Secure checkboxes should be selected next to the token.

Step 2. Set a short expiration time for JWT tokens — 15–30 minutes for the access token; the refresh token can last longer but must be renewed over a secure channel.

Step 3. Enable the SameSite=Strict or SameSite=Lax attribute — this prevents cookies from being sent during cross-site requests and reduces the risk of CSRF attacks.

Step 4. Explicitly delete tokens when the session ends: a proper logout should invalidate the token on the server, not just delete it from the browser.

Step 5. Do not install extensions that request access to all websites indiscriminately. Extensions like Cookie AutoDelete automatically delete cookies when you close the tab.

Step 6. Use a VPN on public networks — this prevents interception at the network level.

Step 7. Verify the result: open DevTools, go to Application → Cookies, find the token, and make sure that the HttpOnly and Secure flags are enabled and that the expiration time is no more than 30 minutes from the current time.

Pros and Cons

Proper token configuration makes an account resistant to most common attacks: network interception, XSS, and CSRF. A short expiration time limits the window for abuse even if a token is successfully stolen. The HTTP-Only and Secure flags operate at the browser level — users don’t notice them, and performance isn’t affected.

On the downside: manual configuration isn’t required everywhere — some services don’t allow access to cookie settings. The short token lifetime means more frequent refresh requests, which theoretically increases the load on the server. On older platforms, certain chat features may behave erratically when SameSite=Strict is enabled.

Common Mistakes

The first and most common mistake is ignoring token flags entirely: neither HTTP Only nor Secure is set, so any script on the page can read the token. The second is using an unpatched browser: outdated versions contain known vulnerabilities that have long been fixed in current releases. The third is disabling security mechanisms to speed up loading: a gain of a few milliseconds isn’t worth leaving a session open. Fourth — tokens aren’t cleared after logging out, accumulating in the browser for months. Fifth — logging into a chat via public Wi-Fi without a VPN: even an encrypted token can be intercepted during a man-in-the-middle attack at the network level.

Service Comparison

In practice, the difference between a short and medium token lifetime is the difference between a few minutes and a few hours in the hands of an attacker in the event of a successful interception.

FAQ

Securing access tokens for chat APIs isn’t a one-time setup — it’s a habit: short JWT lifetimes, the HTTP Only and Secure flags, the SameSite attribute, and regularly clearing sessions. Start with DevTools right now: check what’s next to your token, and fix any gaps by following the steps above.