Yahoo discloses hack of 1B accounts • Hacker News Board

Re: Yahoo discloses hack of 1B accounts

#131

Post by dsacco » Wed, Dec 14, 2016, 11:14 PM UTC

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…

I have been in this situation, and you're correct.

Somewhere in the organization, a product team is going to throw a fit about usability and churn over the decision to reset user passwords en masse, or to force users to change them when they first log in. This isn't a slight against product managers, but one of the clearest indications of a company's overall security culture "health" is how the security, engineering and product teams choose to compromise and "pick their battles." Risk accepting vulnerabilities has a legitimate place when you have to balance product development and usability, but so does pushing back on egregious issues.

I don't have privileged insight into Yahoo's organization, but in this case it's pretty clear the security team should have either been more diligent in conveying the ramifications or less kneecapped by the surrounding org units, depending on the circumstance. More importantly, Yahoo should have "migrated" their passwords in the manner a parallel comment explains in this thread. This is what Facebook and other companies did after maturing their security programs (see "Facebook Onion" on how Facebook transitioned away from MD5).

Also good to note - there is evidence Yahoo's security culture improved over the years. The decision to go with MD5 almost certainly happened in the 90s, and when Tumblr suffered a breach all users were forced to reset their passwords. The capability and awareness was clearly there.

Re: Yahoo discloses hack of 1B accounts

#132

Post by flukus » Wed, Dec 14, 2016, 11:14 PM UTC

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…

Devils advocate because I'm not a free market type: Can we sue companies for data breaches? This could solve the issue with large companies but not fly by night operations.

Re: Yahoo discloses hack of 1B accounts

#133

Post by gist » Wed, Dec 14, 2016, 11:15 PM UTC

ausjke wrote: post #24

I'm speechless. More and more are migrating to cloud these days, I expect more and more epidemic leakage will come. I host everything myself except for email, which is always a headache but contains more private info than all others I manage combined. Maybe it is time to run a small email server again but it is easily said than done, gosh please give me something like a working PGP or whatever for safe emails(PGP is…

Well inbound email is really not a big issue from my experience. The issue (if any) is deliver-ability of outbound email. But that can be handled in any number of ways. (You can use someone else's smtp if there are issues or you can just follow best practices to have a clean ip address they are available).

I have been doing both inbound and outbound for roughly 20 years on our own equipment. But even doing just inbound gives you better control and in a way you are able to lessen the attack surface of being a large vulnerable target.

Re: Yahoo discloses hack of 1B accounts

#134

Post by jsjohnst » Wed, Dec 14, 2016, 11:15 PM UTC

jsjohnst wrote: post #116

niftich wrote: post #51

Earlier quoted context omitted.

Is the info about the Y and T cookies in this pdf [1][2] accurate? [1] (EDIT: now with screenshots) http://imgur.com/a/g61VZ [2] (Not affiliated with link, but the risk-averse may wish to open in a sandbox) ftp://hackbbs.org/milworm/270

Doing a google search for the link showed me the title of the document which I remember reading in the past. The overall coverage of Y&T cookies is more or less accurate at the time of writing back in like 2010/2011, but there's a bunch of mostly minor technical inaccuracies too. I don't want to comment on much without rereading it, but I remember the description of Sled ID made me laugh (which btw I'd guess less tha…

Also, the video that goes with the PDF is too funny! Just watched it on YouTube [0] again. Notice how he doesn't actually sign into Web Messenger, just goes to the login page? If he had, it would've failed. Same thing with him closing the browser before Yahoo Mail loaded. "Sensitive" reads and everything that did a write operation always (unless there was a bug) validated the cookie against the UDB. So even if you stole the signing key, without the values from the UDB, you would have very limited ability to do anything other than the trivial things shown in the video.

[0] https://m.youtube.com/watch?v=n2CNp_zmje8

Re: Yahoo discloses hack of 1B accounts

#135

Post by vel0city » Wed, Dec 14, 2016, 11:15 PM UTC

Canada wrote: post #119

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…

> including no lawsuits Are there are "free market types" who actually believe there shouldn't be any form of sanctions whatsoever for causing harm? I've talked to quite a few hardcore libertarians, and I've yet to encounter anyone who takes it that far.

In Robert Nozick's Anarchy, State, and Utopia he argues the minimal state would be "limited to the narrow functions of protection against force, theft, fraud, enforcement of contracts, and so on." I'd imagine most libertarians would agree basic contract laws and some level of lawsuits should be acceptable to a functioning society.

Re: Yahoo discloses hack of 1B accounts

#136

Post by JonDav » Wed, Dec 14, 2016, 11:15 PM UTC

metafunctor wrote: post #94

ubercore wrote: post #79

Earlier quoted context omitted.

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.

A preimage attack for MD5 has complexity of about 2^123. So, even if you get the MD5 hash for a password, it will be exceedingly hard to find a password that has the same hash (assuming the original password is long and random).

I thought the whole point of the MD5 vulnerability was that the limit was 2^128 and as such there are more inputs that possible output hashes, meaning more possible input collisions.

Re: Yahoo discloses hack of 1B accounts

#137

Post by dmix » Wed, Dec 14, 2016, 11:16 PM UTC

Canada wrote: post #119

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…

> including no lawsuits Are there are "free market types" who actually believe there shouldn't be any form of sanctions whatsoever for causing harm? I've talked to quite a few hardcore libertarians, and I've yet to encounter anyone who takes it that far.

Even anarcho-capitalists, the most hardcore libertarians, believe heavily in the court system.

So I'm not sure what the OP means "without lawsuits". Because lawsuits would most likely be their answer here. Also maybe competition from other email vendors who take your security seriously and doesn't leak 1 billion emails? Or pressure from investors not to create that type of liability?

Pretty obviously a strawman, it's far easier to win such an argument with silly caricatures of libertarians as an opponent... someone who believes that all companies should be able to do whatever they want, without any consequence!

Only the most extreme niche of the already niche group of anarcho-capitalists believe in private courts or private law enforcement. Which does not at all reflect mainstream libertarian thought. Who instead wish for a "minimal" state, which at a very minimum means centralized courts.

I've heard economists argue that economies and societies do not exist without some form of a legal system (chiefs, kings, courts, etc). It's the very core of human co-existence to be able to resolve disputes in a fair and just way.

Re: Yahoo discloses hack of 1B accounts

#138

Post by zzzcpan » Wed, Dec 14, 2016, 11:16 PM UTC

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…

> this gets fixed

This being what exactly? What is a threat model you are talking about? Because it sounds like you think that a typical user account used for porn, social sites and hobby is worth protecting somehow to the extent of government involvement.

Re: Yahoo discloses hack of 1B accounts

#139

Post by grandalf » Wed, Dec 14, 2016, 11:16 PM UTC

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…

> there is no such thing as insurance for this type of breach

There is insurance. Some of the breached accounts likely contained credit card info, and any exploits are covered by existing insurance.

Some of the accounts might contain embarrassing emails, but few people have insurance against hacked disclosure of that sort.

Things like this happen because the public doesn't care. Most people who use Yahoo for email are computer illiterate and are more likely to do things that lead to a breach. They are also more likely to quit using the service if things like 2FA are required.

So in a sense, the invisible hand delivered the service that was demanded, and now the market can correct. Some percentage of the users impacted will learn from the experience and demand higher quality email hosting in the future.

Re: Yahoo discloses hack of 1B accounts

#140

Post by manarth » Wed, Dec 14, 2016, 11:16 PM UTC

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…

  You can only rehash if you have the plaintext password

There are techniques to rehash, even without the plain-text password, and without the user having to login to trigger a rehash.

Drupal 7 used such a technique for upgrades from Drupal 6, migrating from MD5 to a salted sha512 hash, but it's not an uncommon technique.

The old passwords are stored as MD5 hashes in the databases. The MD5 hash is processed through the same techniques as new passwords: a salt and the new sha512 hash. Provide a way to identify whether the origin was a password, or an MD5 hash.

Either way, you end up with a hash. You can identify whether the origin was a password, or an MD5 hash, but you can neither determine the origin MD5 hash, nor the origin password, as the new hash is secure. So even if the original MD5 hash was insecure, the new hash is secure.

When someone attempts to login, you still need to determine which password-validation to use: hash = sha512(salt + password), or hash = sha512(salt + MD5(password)), but the security level is the same.