Simon Willison's Weblog: sidechannel

Side-channel attacking browsers through CSS3 features

2018-06-01T14:54:30+00:00

Side-channel attacking browsers through CSS3 features

Really clever attack. Sites like Facebook offer iframe widgets which show the user’s name, but due to the cross-origin resource policy cannot be introspected by the site on which they are embedded. By using CSS3 blend modes it’s possible to construct a timing attack where a stack of divs layered over the top of the iframe can be used to derive the embedded content, by taking advantage of blend modes that take different amounts of time depending on the colour of the underlying pixel. Patched in Firefox 60 and Chrome 63.

Tags: css3, security, sidechannel, timing-attack

Side-Channel Leaks in Web Applications

2010-03-23T16:24:02+00:00

Side-Channel Leaks in Web Applications

Interesting new security research. SSL web connections encrypt the content but an attacker can still see the size of the HTTP requests going back and forward—which can be enough to extract significant pieces of information, especially in applications that make a lot of Ajax requests.

Tags: ajax, http, security, sidechannel, ssl

Side-Channel Attacks and Security Theatre

2007-08-02T12:30:03+00:00

Side-Channel Attacks and Security Theatre

“In order to mount most of these attacks the attacker must be local [...] every good security person knows that if your attacker has the ability to run stuff on your machine, it is game over, so why are we even caring about these attacks?”

Tags: ben-laurie, openssl, security, securitytheatre, sidechannel