Null Character Hack Allows SSL Spoofing

eldavojohn writes "Two researchers, Dan Kaminsky and Moxie Marlinspike, came up with exact same way to fake being a popular website with authentication from a certificate authority. Wired has the details: 'When an attacker who owns his own domain — badguy.com — requests a certificate from the CA, the CA, using contact information from Whois records, sends him an email asking to confirm his ownership of the site. But an attacker can also request a certificate for a subdomain of his site, such as Paypal.com\0.badguy.com, using the null character \0 in the URL. The CA will issue the certificate for a domain like PayPal.com\0.badguy.com because the hacker legitimately owns the root domain badguy.com. Then, due to a flaw found in the way SSL is implemented in many browsers, Firefox and others theoretically can be fooled into reading his certificate as if it were one that came from the authentic PayPal site. Basically when these vulnerable browsers check the domain name contained in the attacker's certificate, they stop reading any characters that follow the "\0 in the name.'"

Comments

Is the null character valid in a domain name?

[characterZer0]

If not, the CA should not have issued the cert in the first place. Which CA was it?

Re:When C Strings Attack!

[BikeHelmet]

Java strings!

32bit signed int, max length 2GB.

That ought to be enough for anybody. ;) If you need longer, there's special buffer classes that can go longer.

The string also chooses between ASCII and Unicode when initialized, (you can manually set char encoding, as well) so properly cleaned/trimmed ASCII strings don't waste any memory. (Except for the 3 bytes extra that go into a length int, instead of a null char - but those 3 bytes also give you an amazing speedup when you need to know the length of the string.)

I believe C# implements Strings in a similar way.