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Discussion on: Stealing Accounts with an IMG Tag

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Brian Olore

You are right I didn't see the onload part because I'm on my phone haha.

So, how do you get that code in there? Allowing a user to put in a url to an image is VERY different than allowing them to add an HTML element (that has an onload). I conceded that sanitizing HTML, JS and SQL is still a very necessary practice. As others have pointed out the security provided by http-only cookies is also a must have on everyone web developer's checklist.

I'm sorry for sounding negative.... I just feel your post is making things sound scary unnecessarily. I do appreciate your work to expose how things work under the covers in an easily consumable way.

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nastyox1 profile image
nastyox Author • Edited

It's not scary if you know how to stop it from happening! It's important to note that this style of attack (cross-site scripting) is consistently rated the most commonly executed attack method. While it's easy to guard against (as noted at the end of this article), developers that aren't aware of it will almost certainly leave it unguarded. In an unguarded situation, all you'd have to do is paste that cookie-stealing image tag into the comment section, your username field, or wherever else you're meant to be adding text to the website. That's why it's so important to talk about it and not just assume all developers know about it already. It does pose a very real threat if not defended against correctly.

Thanks! I'm glad you're enjoying my content, especially enough to interact with it in the comment sections.