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Discussion on: Please Stop Using Local Storage

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jondubois profile image
Jonathan Gros-Dubois

One problem with the article is that the words 'never' and 'always' are used way too often.

Also, the article says that localStorage is insecure quite often but doesn't give any evidence or examples.

I would argue that localStorage is as secure as cookies (including httpOnly cookies).

localStorage uses essentially the same security policy as cookies; one of its core principles is that a domain cannot access localStorage data that was created under a different domain so there is no chance that a website could steal data from a different website.

Also, httpOnly cookies do not make your site any less vulnerable to XSS attacks; if the attacker manages to inject a malicious script into your front end, then they can use that script to make HTTP requests to your server (directly from the victim's browser) and your precious httpOnly cookie (containing the user's valid session ID) will be attached to every request so the server will service them without suspecting anything.

The only real difference is that if the token (e.g. JWT) is in localStorage then the attacker can steal the token to use later (same goes for regular non-httpOnly cookies BTW)... Which is hardly a convenience because it's more advantageous for the attacker to carry-out the attack in-place from the victim's browser rather than from the attacker's own machine (thus allowing their IP to be traced directly).

Also, with JWTs, it's good practice to set short expiry dates. If you're using WebSockets you can even issue JWTs with 10 minute expiry (for example) and re-issue a new one automatically every 8 minutes if the user is still connected and logged in; then when the user logs out or becomes disconnected; their last issued JWT will become invalid in only 10 minutes (at which point it becomes completely useless to an attacker).

Also, it's not recommended practice to store large amounts of data inside a JWT because of the overhead of having to send it with every request/connection.

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ilusionlinux profile image
Luis Morales

woow this is one of the best comments in this post.

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rugk profile image
rugk

Indeed the original article totally misses the point that local storage is by no means less secure than any other part of your website. If you have an XSS, you are flawed. That's actually the reason why XSS attacks are so serious/bad.

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ivankleshnin profile image
Ivan Kleshnin

If you fetch from the browser, you don't get cookies. You have to add {credentials: "include"}. And that requires a whitelisting on the server. So no, it's no so easy to get httpOnly cookie content in browser as you describe. It requires a TRACE method or other known vulnerability or bug to expose them. Pls. prove me wrong if you think otherwise.

Other than that, I agree with your point. When an app has an XSS injection there are tons of attack vectors a hacker can take. And yes, localStorage is almost the same as cookies security-wise. This article is mostly a FUD, unfortunately.

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maciek134 profile image
Maciej Sopyło

His point was that you don't need to read the cookie if you can send requests when the user is on the compromised website.