Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Password crack [affecting OAuth and OpenID] could affect millions

computerworld.com

Post reply on HN
Print view View original

11–20 of 61 posts

Re: Password crack [affecting OAuth and OpenID] could affect millions

#11

Post by tptacek »

edanm wrote: post #9

"On some login systems, the computer will check password characters one at a time, and kick back a "login failed" message as soon as it spots a bad character in the password. This means a computer returns a completely bad login attempt a tiny bit faster than a login where the first character in the password is correct." This doesn't sound right to me. Aren't passwords usually checked by hashing the entire password an…

Yes, systems that hash passwords aren't timeable, because attackers can't "propose" a hash that is correct to the first N bytes in order to find byte N + 1.

If you are comparing literal passwords, you may have something more to be concerned about.

Re: Password crack [affecting OAuth and OpenID] could affect millions

#12

Post by steveitis »

ronnier wrote: post #5
thrill wrote: post #2

if timing is so critical to these attacks, it seems adding a tiny variable (on the order of a millisecond) in response times would completely prevent this

On the second page of the article: >Program the system to take the same amount of time to return both correct and incorrect passwords. This can be done in about six lines of code, Lawson said.

Only by introducing a delay where is none is needed.

This makes things slower for the rest of us. 1 extra millisecond per user * 8 billion users * times 10 logins a day == Lots Of Lost Man Hours, probably enough to rebuild the great pyramids of Egypt by hand every year.

Security researchers are the reason we can't have nice things. :)

Re: Password crack [affecting OAuth and OpenID] could affect millions

#13

Post by tptacek »

steveitis wrote: post #12
ronnier wrote: post #5

Earlier quoted context omitted.

On the second page of the article: >Program the system to take the same amount of time to return both correct and incorrect passwords. This can be done in about six lines of code, Lawson said.

Only by introducing a delay where is none is needed. This makes things slower for the rest of us. 1 extra millisecond per user * 8 billion users * times 10 logins a day == Lots Of Lost Man Hours, probably enough to rebuild the great pyramids of Egypt by hand every year. Security researchers are the reason we can't have nice things. :)

The funniest part about these discussions is that we're discussing an optimization that exclusively helps attackers. Virtually all HMAC candidate hashes are correct all the way through the final byte, meaning that even in a classic short-circuited compare, you still have to read everything. In virtually all traffic, you never get to take that short circuit. The only time short-circuited comparisons ever make things faster is when an attacker is waiting for a rejection.

Re: Password crack [affecting OAuth and OpenID] could affect millions

#14

Post by callahad »

tptacek wrote: post #10

Everyone who reads HN is smart enough to simply read the primary source for this: http://lists.openid.net/pipermail/openid-security/2010-July/... Follow the thread. Nate is Root Labs, Taylor works for him. This is the same vulnerability as Nate found in Google Keyczar last year, and that Coda Hale found in Rails several months ago. Until people start handling crypto flaws the same way we handle buffer overflows, swee…

Wow, there are some fantastically stubborn, yet civil minds in that thread. I like Nate's reference to writing a blog post "to help people skip the standard progression of awareness to timing attacks."

"Standard progression of awareness" is a wonderful term.

Re: Password crack [affecting OAuth and OpenID] could affect millions

#15

Post by chaostheory »

tptacek wrote: post #10

Everyone who reads HN is smart enough to simply read the primary source for this: http://lists.openid.net/pipermail/openid-security/2010-July/... Follow the thread. Nate is Root Labs, Taylor works for him. This is the same vulnerability as Nate found in Google Keyczar last year, and that Coda Hale found in Rails several months ago. Until people start handling crypto flaws the same way we handle buffer overflows, swee…

Able to read it easily yes. Finding it during work hours - not me personally =) Good find.

Re: Password crack [affecting OAuth and OpenID] could affect millions

#16

Post by Groxx »

thrill wrote: post #2

if timing is so critical to these attacks, it seems adding a tiny variable (on the order of a millisecond) in response times would completely prevent this

That effectively already exists. The internet isn't instant or consistent, and this is about remote timing attacks.

Re: Password crack [affecting OAuth and OpenID] could affect millions

#17

Post by [deleted] »

steveitis wrote: post #12
ronnier wrote: post #5

Earlier quoted context omitted.

On the second page of the article: >Program the system to take the same amount of time to return both correct and incorrect passwords. This can be done in about six lines of code, Lawson said.

Only by introducing a delay where is none is needed. This makes things slower for the rest of us. 1 extra millisecond per user * 8 billion users * times 10 logins a day == Lots Of Lost Man Hours, probably enough to rebuild the great pyramids of Egypt by hand every year. Security researchers are the reason we can't have nice things. :)

[deleted]

Re: Password crack [affecting OAuth and OpenID] could affect millions

#18

Post by phreeza »

Does anyone know how feasible this kind of attack is with real world network latency and server load fluctuations? In the end it comes down to statistics, but i could imagine forging a token this way might take a very high number of failed attempts, which might then trigger other security mechanisms?

Re: Password crack [affecting OAuth and OpenID] could affect millions

#19

Post by blasdel »

callahad wrote: post #14
tptacek wrote: post #10

Everyone who reads HN is smart enough to simply read the primary source for this: http://lists.openid.net/pipermail/openid-security/2010-July/... Follow the thread. Nate is Root Labs, Taylor works for him. This is the same vulnerability as Nate found in Google Keyczar last year, and that Coda Hale found in Rails several months ago. Until people start handling crypto flaws the same way we handle buffer overflows, swee…

Wow, there are some fantastically stubborn, yet civil minds in that thread. I like Nate's reference to writing a blog post "to help people skip the standard progression of awareness to timing attacks." "Standard progression of awareness" is a wonderful term.

The reply in question: http://lists.openid.net/pipermail/openid-security/2010-July/...
Post reply on HN