Re:Internet Explorer 11 (IE11) to be retired on June 15, 2022
by fomine3 on Thursday May 20, 2021 @01:37AM
(#27217803)
> You can already use url() to load background images - seems like this is a solved vector.
Background image with url() is very easy to be whitelisted because it's very similar to <img> tag.
> Does this really increase the attack surface area, since you can't execute javascript from the iframe?
Sorry, this concern isn't about security for browsers, but for text editable email without indication. Maybe you can argue that it's not a problem because external image is already replaceable, but IMO it's more problematic.
> No, because that's not in the HTML/CSS spec and modern browsers don't support it.
Blacklist approach means that any tags just work unless explicitly specified on blacklist. "Not in spec" won't help.
> Seems like a solved problem considering there's currently no way to execute arbitrary javascript in webmail.
Background image with url() is very easy to be whitelisted because it's very similar to <img> tag.
> Does this really increase the attack surface area, since you can't execute javascript from the iframe?
Sorry, this concern isn't about security for browsers, but for text editable email without indication. Maybe you can argue that it's not a problem because external image is already replaceable, but IMO it's more problematic.
> No, because that's not in the HTML/CSS spec and modern browsers don't support it.
Blacklist approach means that any tags just work unless explicitly specified on blacklist. "Not in spec" won't help.
> Seems like a solved problem considering there's currently no way to execute arbitrary javascript in webmail.
That's thanks to whitelist approach.