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Yahoo discloses hack of 1B accounts

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Re: Yahoo discloses hack of 1B accounts

#141

Post by cm2187 »

Endy wrote: post #123
cm2187 wrote: post #107

Earlier quoted context omitted.

But it's not like if we didn't have a pretty much continuous stream of major data leaks for the past 5 years. Surely yahoo engineers occasionally open a newspaper...

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 the bcrypt hash you have stored.

I am not a crypto expert but intuitively it doesn't look like I would have weakened the security that way. You can't really attack bcrypt(md5(password)) much more than bcrypt(password). Can you?

Re: Yahoo discloses hack of 1B accounts

#142

Post by Endy »

SomeCallMeTim wrote: post #90
AdmiralAsshat wrote: post #39

Well on the upside, if you changed your password as a result of the hack from a few months ago, you should theoretically be safe against this one which happened in 2013 . Those security questions, on the other hand, are still fair targets.

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".

Re: Yahoo discloses hack of 1B accounts

#143

Post by funnyfacts365 »

yuhong wrote: post #95
pluma wrote: post #83

Earlier quoted context omitted.

As a data point: when I was a teenage code monkey in 2004 writing PHP I already understood that unsalted MD5 is unsafe. According to Wikipedia: * 2004 it became possible to find MD5 collisions at a rate of one per hour on a cluster * 2005 it became possible to do this within "a few hours" on a consumer laptop * 2006 it became possible to do this within one minute * nowadays it's possible to do this "within seconds" P…

MD5 collisions are probably not important for passwords.

Care to explain? The hashes are what is compared so it seems it's important.

Re: Yahoo discloses hack of 1B accounts

#145

Post by Normal_gaussian »

camus2 wrote: post #36
xanadohnt wrote: post #29

Earlier quoted context omitted.

Web tokens, for example, don't necessarily include just a session ID. Some include the full session details within its payload. This can be quite useful, actually, because it offloads session-lookup onto the client.

How do you invalidate a JWT server-side without the user interacting with the server ?

My preferred method:

Add an "expires" field to the token, this should contain a date after which the token is no longer valid. Now all token s auto-invalidate after a certain period.

Allow some or all tokens to "refresh" by calling a particular endpoint (call with valid token and get a token with expiry from now).

Optionally add some form of identifier to the token (user_id works great) so that you can push a message out to your servers that looks like this: "All tokens for x expiring before y are invalid". Once time y has passed your server can forget about the message. This will be a very small set (often 0) as very few people use the "log out my devices" features.

Logouts should be done client side by deleting the token.

If you are worried about your token being sniffed you are either not using HTTPS, or sticking it somewhere stupid.

Re: Yahoo discloses hack of 1B accounts

#146

Post by flukus »

haser_au wrote: post #98
x0 wrote: post #75

Earlier quoted context omitted.

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…

There are likely to be a lot of identity systems using the password in the database, all of which have been coded to look for an MD5 hash, not a salted hash. This means code in a number of applications have to be updated at the same time. The typical way around this is to create your new destination column (e.g. sha256 with salt), and progressively have applications reference this column rather than the MD5 unsalted…

> It's a huge amount of work, and if the applications were made in 1990's, the code is likely legacy.

Which begs the question, can legacy code survive in an international network?

Re: Yahoo discloses hack of 1B accounts

#147

Post by cuckcuckspruce »

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…

>I'm not really a software developer but...

If I had a nickle for every time I've heard this statement then I'd have enough to comfortably retire.

Yes, in theory, changing a column in a database (which in this case, happens to be a password) seems simple, but in practice, it's not.

Re: Yahoo discloses hack of 1B accounts

#148

Post by harigov »

obmelvin wrote: post #38
harigov wrote: post #3

I hope they stopped depending upon those security questions if that is part of the leak. On a side note, this seems like a great time to be an abuser. One can collect so much information about users - they may actually have more data than any govt in the world.

Did you catch this? "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." While I agree with your sentiment towards security questions, they…

No, that part of the article wasn't there when I read it. Interestingly, the article ended with the word "Developing". I believe they meant that the article will be updated as and when they receive more information.

Re: Yahoo discloses hack of 1B accounts

#149

Post by sleet »

ashark wrote: post #105
x0 wrote: post #75

Earlier quoted context omitted.

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…

Well, you can only rehash if you have the plaintext password. So you have to wait until they login again, or force a password reset for everyone. In the former case you're stuck with a bunch of md5 passwords hanging around for any account that's not very active, and for the latter you'll lose some percentage of active accounts whose reset process is for some reason no longer functional. You could mix-and-match the tw…

x0's algorithm was secure_hash(md5(pass), salt), you already have md5(pass) so this can be done in one bulk update.

Re: Yahoo discloses hack of 1B accounts

#150

Post by csallen »

rukittenme wrote: post #129
cmurf wrote: post #111

OK so I'd like to invite the pure free market types to explain how this gets fixed without any government, including no lawsuits. Because I keep hearing from free market types that 100% of phishing victims are ignorant and basically deserve what happens to them, if they can't learn that they're being duped they deserve to be duped, they somehow think wholesale loss of trust ends up being focused only on specific comp…

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.
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