On: Insecure by default – hijacking websites that use target=“_blank”

[Retr0spectrum]

This is a nice demonstration, although I feel like it would be more useful to show that it works across domains (Which IMHO is the most important part).

[aji → Retr0spectrum]

Yeah, having never heard of this before, I'm a little shocked. Can you access things like window.opener.document?

Fortunately, tabs created by opening the link using the middle mouse button don't seem to have a useful window.opener. Guess I'll be more deliberate about that habit.

[yeldarb → Retr0spectrum]

Does it actually work cross domain? That would really surprise me.

Edit: if I understand correctly this only allows the opened page to navigate the opening page; it does not allow it to do anything else to the opener. Is that correct?

[aji → yeldarb]

I don't know about the cross-domain case but on the same "domain" (file: protocol) I used the following two HTML files

link.html:

    <a id="link" href="opener.html" target="_blank">Click</a>

opener.html:

    <script>window.opener.document.getElementById("link").href = "https://google.com";</script>

and sure enough the link was changed. If this works cross-domain, this is kind of a big deal, isn't it?

[Retr0spectrum → aji]

See this comment for a cross-domain demo: https://news.ycombinator.com/item?id=11631810

It's a fairly big deal, but not much is being done about it on the browser side of things. It can only really be used for phishing style attacks.

[magicalist → Retr0spectrum]

you cannot access the opener's document as aji's example does cross origin

[Retr0spectrum → magicalist]

Sorry, I didn't read the comment carefully enough.

I assumed we were still talking about window.opener.location (which can be modified across domains)