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Yahoo discloses hack of 1B accounts

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Re: Yahoo discloses hack of 1B accounts

#181

Post by SomeCallMeTim »

Endy wrote: post #142
SomeCallMeTim wrote: post #90

Earlier quoted context omitted.

I had a Yahoo account entirely to use a Yahoo email list; I used to have it for Yahoo chat, but I haven't used that in years. So I ignored the hack a few months ago. I also never got notified that I was vulnerable. Just now I tried to log in to see if my password had been invalidated. Nope. It was my old insecure "pattern-based" password (myprefixYAHOO) that I use nowhere any more. Probably short enough to have brute…

It's more that there's more then 1B accounts out there - remember that this isn't just "yahoo.com" that got affected, it's Yahoo, YMail, RocketMail, yahoo.co.jp (a HUGE community btw), and several others which all fall under the "Yahoo accounts" umbrella. Not every account was hacked by any means; terrifyingly, the number of accounts isn't nearly what you'd expect as a percentage of "Yahoo accounts".

Makes me wonder what service or other sub-section of Yahoo actually got hacked, then. Doesn't seem to say in the article.

Re: Yahoo discloses hack of 1B accounts

#183

Post by kuschku »

chillydawg wrote: post #16
kuschku wrote: post #12

Earlier quoted context omitted.

[deleted]

No, sorry. They're borderline criminally negligent. When you have 1bn passwords stored in raw md5, a decade after the first rainbow tables were published, then you don't deserve anyone's business or your freedom.

Sure, it's borderline negligent.

But it's already a godsend compared to what many banks do, storing passwords in plaintext, sending reset passwords via plaintext email, requiring 4-8 character passwords that can only contain digits and a limited set of characters, etc.

I'd be more than happy if any bank would follow Yahoo!'s password standards.

Re: Yahoo discloses hack of 1B accounts

#184

Post by noonespecial »

cm2187 wrote: post #141
Endy wrote: post #123

Earlier quoted context omitted.

From everything I've read, the engineers did. The problem was that the security team had to go head-to-head with the budget team. And unfortunately, the budget team won - since the upper levels didn't feel that the IT security salaries were a necessary expenditure. And beyond that, there was concern that making people actually change their passwords regularly and requiring anything like security in said passwords was…

But would it require users to change their password? The way I would have implemented it, but would be keen to know how secure it is, is that you start with the md5 of the password ( md5(password) ). You then bcrypt or scrypt that md5 ( bcrypt(md5(password)) ) and replace the md5 in your database with the bcrypt hash. When a user logs in, all you need to do is to calculate the md5 first then check that md5 against th…

The problem is in collisions. Md5(password) can yield the same result for many different values of password so simply bcrypting that result means that you start with a restricted possibility space. So less secure. Punts the question to how much less secure. Seems to me it would still be worth it to do and then all new passwords going forward are done correctly.

Re: Yahoo discloses hack of 1B accounts

#185

Post by parenthephobia »

ubercore wrote: post #79
alyandon wrote: post #11

"Separately, we previously disclosed that our outside forensic experts were investigating the creation of forged cookies that could allow an intruder to access users’ accounts without a password. Based on the ongoing investigation, we believe an unauthorized third party accessed our proprietary code to learn how to forge cookies." So that exactly explains how my Yahoo account was used to send spam despite having a pa…

What do you mean by a password that can't be reasonably brute forced? EDIT: To clarify, I mean specifically with md5. I'm by no means an expert, just curious because I had considered md5 so broken that this comment caught my attention.

Rumours of MD5's death have been greatly exaggerated.

MD5's weakness is that it's (relatively) easy to produce two strings which have the same hash. However, given an MD5 hash, it's not easy to produce a string which also has that hash.

In principle, one could intentionally construct two passwords which have the same hash. It's hard to see how that could be exploited maliciously - any attacker knows both passwords to begin with. Even then, making colliding strings that would make acceptable passwords hasn't been done yet, AFAIK: the shortest colliding strings found so far are 64 bytes long and contain several unprintable characters.

OTOH, computers are fast enough now that brute-forcing MD5 is practical for short strings with a limited set of characters, which is what passwords tend to be. One should use algorithms like PBKDF2, scrypt, and bcrypt which can increase their complexity as the computation capacity of potential attackers increases. This isn't because of a particular weakness in MD5, though, and one should equally avoid storing passwords as SHA-512 hashes, say.

The thing you definitely shouldn't use MD5 for is digitally signing a file you didn't make, because it's possible that whoever did make it also made another file with the same MD5 hash, for which your signature would also be valid.

Re: Yahoo discloses hack of 1B accounts

#186

Post by xxs »

x0 wrote: post #75
dopamean wrote: post #56

Earlier quoted context omitted.

I'm genuinely curious how the decision to use MD5 gets made. Who says, "hey, maybe we should use MD5." And then who responds, "that sounds like a great idea Bob." Seriously. I've known for years that MD5 is insufficient for hashing passwords and I'm just some random guy. This kind of thing really baffles me.

And nobody ever seemed to say "hey, maybe we should be using something more secure". Yahoo's been around for how many decades, and the fact they were still using MD5 in 2013 is just shameful. Yeah if it was some legacy code from 1993 you can probably excuse it, but I just can't believe after 20 years nobody thought it was a problem. I'm not really a software developer but I really can't imagine it being a huge change…

Normally you'd =not= store the salt separately; the usual way is keeping the salt and the password together in the same 'blob'

Rehashing can be safely implemented as long as the auth. process can handle both md5 and some composite hash [i.e. shash(md5(pwd))]

It's really a trivial operation.

Re: Yahoo discloses hack of 1B accounts

#187

Post by terrib1e »

ubercore wrote: post #79
alyandon wrote: post #11

"Separately, we previously disclosed that our outside forensic experts were investigating the creation of forged cookies that could allow an intruder to access users’ accounts without a password. Based on the ongoing investigation, we believe an unauthorized third party accessed our proprietary code to learn how to forge cookies." So that exactly explains how my Yahoo account was used to send spam despite having a pa…

What do you mean by a password that can't be reasonably brute forced? EDIT: To clarify, I mean specifically with md5. I'm by no means an expert, just curious because I had considered md5 so broken that this comment caught my attention.

Definitely check this episode of 'Hacked' out for a simple overview. I just started listening to this show. It's a shame there are so few episodes.

http://www.hackedpodcast.com/episode-3-the-problem-with-pass...

Re: Yahoo discloses hack of 1B accounts

#189

Post by 0x0 »

alyandon wrote: post #11

"Separately, we previously disclosed that our outside forensic experts were investigating the creation of forged cookies that could allow an intruder to access users’ accounts without a password. Based on the ongoing investigation, we believe an unauthorized third party accessed our proprietary code to learn how to forge cookies." So that exactly explains how my Yahoo account was used to send spam despite having a pa…

Are you sure they actually logged in to your account to send spam (are the spam emails visible in your sent folder), or could it be that someone is just spoofing the SMTP MAIL FROM / email From: header?

Re: Yahoo discloses hack of 1B accounts

#190

Post by rukittenme »

csallen wrote: post #150
rukittenme wrote: post #129

Earlier quoted context omitted.

You're building a straw-man. Before trying to argue against a position you should try to understand it.

On a similar note, if you're going to tell someone they're wrong about something, you owe it to them to explain why. Otherwise they won't (nor should they) take your feedback seriously.

I did. I said the person was building a straw-man and can solve it by understanding the topic more. That means research free market capitalism then present an argument.
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