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We use scrypt for passwords hashing. This is modern hard to crack password hashing algorithm. We do have database access logs, so it was pretty straightforward
by kpumuk 13y ago
We use scrypt for passwords hashing. This is modern hard to crack password hashing algorithm.
We do have database access logs, so it was pretty straightforward to identify which users were affected.
- the1 13y agohttp://www.scribd.com/password/check http://www.scribd.com/password/check thank you for this. now I can run a list of emails against this to see who has scribd account
- the_french 13y agoThey can modify it to simply say whether your account was compromised, regardless of whether you have an account (ie, if no account -> not compromised).
- wuest 13y ago...Which they ought to do. Offering the ability to enumerate user accounts is unlikely to be the immediate goal of this utility, but it's an effect nonetheless.
- lelandbatey 13y ago30 minutes later and it's fixed. Entering an invalid email also results in a "this email was not compromised" message.
- yahelc 13y agoThat's what they're doing. "aijaspijasohisaho@asoihdshohdusudhs.com" gets a message saying that that account wasn't compromised.
- deleted 13y ago[deleted]
- dopamean 13y agoI just put in a bunch of fake email addresses and they all returned with "Good news - your password has not been compromised." I think the only confirmation that youd get of an existing account is if the password was compromised.
- psycr 13y agoThat's good to hear. As a future suggestion to anyone else who finds themselves in this unfortunate situation - including some technical granularity in your press release can go miles in offering reassurance to your technical audience/users.
- jasonlotito 13y agoWhy? Honestly asking: what difference does this have on the end result? Now that you know they are using scrypt, how will that impact your actions? You could say that this has a bearing on whether you continue to use the service, but if that were the case, wouldn't it be better to suggest that all services provide this information up front?
- bradleyland 13y agoYou will not successfully maintain positive customer relationships by boiling all customer interactions down to questions like "how will that impact your actions [right now]?" Relationships are a string of positive and negative experiences that must be carefully curated. The decision to remain in a relationship is rarely a singular event (related to a singular experience). You could think of it more as the cumulative result of all relationship experiences. Even the best relationships involve some negative experiences, but the important part is making sure those negative experiences are mitigated as best as possible. Customers will give more leeway to vendors with whom they have a strong NET positive relationship. There are two important technical points that could have been included to great effect: 1) That they store the encryption scheme with the password record so that they can upgrade their crypto incrementally. 2) That their most recent auth algorithm uses scrypt. So how do these two points directly impact the mitigation of what is otherwise a negative experience? First up we should look at users who will understand what points 1 & 2 mean. These users will respond positively to these items, because it changes the conversation from "Scribd just got h4x'd" to "Hey, at least they had good crypto in place." The next tier of users will come along, read these comments, and feel more confident that the community of knowledgable people around them are feeling OK about this, so they should too. As to the question of, "wouldn't it be better to suggest that all services provide this information up front?" I would say yes, it would. This action is not mutually exclusive of including technical details in this communication though.
- MattBearman 13y agoThanks for clarifying, good to see you're using a decent hashing algorithm :) I'm still a little unsure of how you are able to know some users had their password compromised. Is it a simple case of finding successful log in attempts from the same IP address as attack?
- kpumuk 13y agoCompromised != Hacked. To clarify: no accounts were accessed by the hackers, but small amount of account records have had passwords encrypted with outdated algorithm (basically SHA1 + salt), so we preemptively reset their passwords and sent out emails to all affected users. This is how we define "compromised" - people which had their passwords hash with old algorithm, which is relatively easy to crack.
- zwegner 13y agoThis seems to imply that many of (all?) the emails/encrypted passwords were leaked, but you don't consider most of them "compromised"...
- sakai 13y agoI'd like to echo this concern -- were all emails/encrypted passwords leaked, but you only consider those protected by outdated hashing schemes to be compromised? If so, I feel you have an obligation to alert ALL of your users.
- hackerguard 13y agoAdditional question: when did users first alert you to the hack?
- nikcub 13y agothat is a weird definition of compromised. is it true that all, or greater than 1% of, emails and hashes were dumped? I find it hard to believe you migrated 99% of passwords to a new scheme. I've never seen over 60%, and that is with a lot of prompting to users (and as as Scribd user i've never been prompted)
- spizzo 13y agoSo what do you do past this point? I know you can probably rough out how much time it would take to find hash collisions and ask as your users to change their passwords before that amount of time elapses, but past that point, can't you no longer assume that it's the actual user logging in to change their password?
- sveiss 13y agoWe performed a forced password reset on the users with compromised hashes. The old password will not work on Scribd, and those users will need to go through the password reset flow to regain access.
- spizzo 13y agoAh ok. I was wondering how you verified the users' identity if the password was compromised. That makes sense, thanks!
- kpumuk 13y agoWe have reset passwords for all affected users. Hashes that got leaked are not useful now.
- icebraining 13y agoWell, that assumes people aren't reusing those passwords.
- beachstartup 13y agohttp://en.wikipedia.org/wiki/Salt_(cryptography) http://en.wikipedia.org/wiki/Salt_(cryptography)
- harshreality 13y agoSalts make cracking a list of N password hashes take roughly N times as long, but if a password is cracked anyway (because it's common and/or because the hash is not using very many rounds, or because an attacker only cares about one particular account), and the password is reused elsewhere, the fact that it was salted doesn't matter anymore. GP is right; if owners of the leaked accounts [email, hash] pairs are reusing passwords, the leaked hashes are potentially useful even though scribd has reset them. They're simply not useful for logging in to scribd.
- thirsteh 13y agoYou should add this. Savvy people will be positively surprised to see a company actually caring about doing password authentication right.
- tptacek 13y agoThat is awesome. You should feel comfortable telling people this; it puts you way ahead of the game.
- A1kmm 13y agoCan I suggest you also share what parameters you use with scrypt? Scrypt is parametric and you can choose weak or strong choices for parameters depending on how long you want to spend validating passwords.