Shmoo Group Finds Exploit For non-IE Browsers

shut_up_man writes "Saw this on Boing Boing: East coast hacker con Shmoocon ended today and they had a nasty browser exploit to show off... using International Domain Name (IDN) character support to display fake domain names in links and the address bar. Their examples use Paypal (with SSL too) and this looks very useful for phishing attacks. Interesting note that it works in every browser *except* IE (which makes this exploit a lot less dangerous in the end, I suppose)."v The reason IE isn't vulnerable is because it doesn't natively support IDN; with the right plug-in, it too is vulnerable.

Comments

Are phishers going to bother with this, though?

[The I Shing]

I'm surprised to hear that Microsoft's refusal to adopt international standards in their browser actually thwarts a potential phishing attack rather than aiding it. If the problem can't be fixed in the browsers, maybe email clients and websites can find some way of decoding, detecting, and disabling such links. Are phishers going to bother trying to use this exploit if it works on less than 10% of their potential victims?

Known for years....

[Chris_Jefferson]

Seriously, it's been known for years that adding international character sets was going to cause the problem of multiple identical (or almost identical) characters.

On the other hand, no-one really seems sure of the best way to fix it... One option is obviously to mark somehow when non-ASCII characters are used, but while this will help the people who only want ASCII URLs, it will still leave the problem for everyone who wants to use this extended system, making it effectively useless....

IDNs were a bad idea anyway

[Anonymous Coward]

Except when implemented in their own country code namespace of course.

There are so many characters that look alike, that it is trivial to register a domain name that will look the same as another one. Typically the different character would only be recognised by a native that used that character, although using it alongside normal English characters would probably throw them off as well.

Solution? Maybe an "IDN" icon in the URL bar, or a warning if an IDN uses a mixture of normal English characters with some foreign characters in an IDN.

Douglas Hofstadter: When an A is not an A

[G4from128k]

This brings up the amusing problem of character recognition by human and non-human intelligences. Douglas Hofstadter discusses this issue in on seeing A's and seeing As.

In the case of this exploit, a deep flaw in IDN and computer fonts means that character #1072 is rendered typographically as an "a". The irony is that this is one of the few cases in which a computer can readily tell the difference between "a" and #1072 and a person cannot. The only solution would be rules that prohibit isomorphic characters in typefaces or a in-browser warning system that analyses the potential for ambiguity and alerts the user.