A recent security incident involving Dropbox Sign | Hacker News Reader

A recent security incident involving Dropbox Sign

sign.dropbox.com

213 pointsJonoBB69 comments

This is Dropbox Sign, not Dropbox. It’s a document signing product akin to Docusign, and was called Hellosign before Dropbox acquired them.

We are a customer of theirs at my startup, and as far as I can tell Dropbox has made very few changes since the acquisition beyond changing the branding. So I wouldn’t take this incident to be an indicator of much on the cloud-storage side of the company.

Acquired in 2022? IMO that's enough time to bring their service up to the same security standard as the rest of their services, assuming it's a priority.

Google and others normally have a 6 month grace period for bug bounty reports in acquisitions.

> that's enough time to bring their service up to the same security standard

If you can get competent people to work for you while keeping Wall Street happy, sure, but there are much "cooler" companies across the street that Wall Street is more excited about, are hiring right now, and the competent folk are going there.

At the end of this extreme is Equifax-like companies that have leaks and lots of other issues. Before you ask why Equifax sucks so much, ask yourself: Would you work there? No? That's why they continue to suck.

While Dropbox isn't Equifax, it isn't OpenAI or NVIDIA right now.

I worked at equifax.

Just sort of ended up there when the fun startup I was at got acquired by them. I soon burnt out and checked out mentally and eventually they noticed and we parted ways.

I just wish I had had the wisdom to get myself out before I burnt out. Looking back, it was a slowly boil the frog type of situation.

Yeah after nearly 2 years it probably isn't a credible excuse in any way.

We’ve been with hellosign for years and Dropbox has done a great job of stabilizing them. I will tell you that they have put in a ton of ops work to keep the platform up more consistently.

True, they have been more stable since the acquisition now that you mention it.

Our implementation of their API was a bit of a mess so it can be hard to see through our own crap sometimes to give credit where its due haha.

It should also be a reminder for Dropbox that acquiring a product then allowing it to languish risking security vulnerabilities -- will, appropriately, have negative brand perception implications that affect your main product too.

"Upon further investigation, we discovered that a threat actor had accessed data including Dropbox Sign customer information such as emails, usernames, phone numbers and hashed passwords, in addition to general account settings and certain authentication information such as API keys, OAuth tokens, and multi-factor authentication."

hashed passwords, API keys, OAuth tokens, MFA...

Oh no.

I use Dropbox Sign API, so a little fearful our private data was accessed. API keys were leaked as part of this hack. It's unclear from press release if hackers used the API keys to access data/documents of customers.

April 24th they became aware of issue, reporting it over a week later. I'd also be curious on how long this problem went on before being detected on April 24?

I suppose more will come out in the coming days..

Hashed passwords? Surely they mean hashed and salted passwords. Right? Right???

They were using SHA1, then they migrated.

68 million accounts dumped: https://www.theguardian.com/technology/2016/aug/31/dropbox-h...

https://www.troyhunt.com/the-dropbox-hack-is-real/

now they first hash the password using SHA512 (with a per-account salt)

then they hash the password with bcrypt (with the default strength)

then they encrypt the password with a key that the application server runs with, but that is not stored in the database.

So yes, hashed and salted.

This hack seems to affect the Dropbox Sign application, which is based on HelloSign which they acquired a few years ago. It’s still running on the hellosign.com domain and seems mostly separate, so it wouldn’t surprise me if they also store passwords differently.

That… seems excessive. Is it just security theater or actually useful somehow?

Useful because you can support existing passwords without requiring everyone to login or reset their password. Still has flaws though, like password shucking.

They encrypt the salted password hash?

> Based on our investigation, a third party gained access to a Dropbox Sign automated system configuration tool. The actor compromised a service account that was part of Sign’s back-end, which is a type of non-human account used to execute applications and run automated services. As such, this account had privileges to take a variety of actions within Sign’s production environment. The threat actor then used this access to the production environment to access our customer database.

Not familiar with this area, how usually does it happen? Social engineering or some more "technical" ways?

Also, under normal (not hacked) circumstance, who usually would have access to these service accounts?

The credentials for service accounts are generally available to a system admin but I think in most cases it would be a strange request to ask for them, so not a strong vector for social engineering.

A service account is used to give limited permissions on one system to another system. Normally only that system would need access to them, not any human.

Their main benefit is that, since no person is trying to do their day job here, the account can be locked down to precisely the permissions it needs. The reality is that service accounts are usually given extremely permissive access initially and then forgotten about. This makes them juicy targets for attackers.

I really recommend listening to the Darknet Diaries podcast (available on Spotify at least). Really high-quality interviews with both ex and current hackers, cybersecurity professionals etc.

That's why e2ee is key, decentralised tooling for these types of applications is the way (even if the UX is not as good yet)

I love Dropbox but stuff like this is a good reminder to re-evaluate using any service that store large amount of personal data without e2ee. I understand that partly because of block-level diffing and syncing, it's hard to provide true e2ee for Dropbox, but it's still a big reason why I'm having most of my stuff in iCloud Drive (with Advanced Data Protection), despite liking Dropbox much more.

Hope they'll come around and add it at some point, and not just for businesses as hinted at when they acquired boxcryptor.

(Cryptomator and encrypted sparsebundles work great on Dropbox. Just annoying to manage)

Dropbox offers end-to-end encryption now (for business teams):

https://blog.dropbox.com/topics/company/new-solutions-to-sec...

I'm not a business, I'm a paying customer on the most expensive personal tier. It's silly that they don't offer this feature for me. I also can't upgrade to a business plan because those require at least 3 users.

It just feels like feature gatekeeping to me, but no way for me to pay more to get this feature. But I also understand that personal users are not Dropbox's main focus.

A Synology/QNAP/TrueNAS NAS is a far better solution, with no restriction.

We all are probably guilty of falling for the convenience trap here or there. But setting up the sync between Dropbox and the NAS (Synology user here) with a one-way, don't delete, don't overwrite policy is a good lifeline to have - you know, just in case...

I'm a big advocate for running a NAS, but using a service like Dropbox means there's one fewer personal device that needs babysitting.

QNAP does not seem secure at all, IMO its not worth it. I have not used the others you mentioned.

You would still need somewhere to do off site backups to.

(Edit: changed offline to offsite)

Isn’t that what a Synology offers? An offline backup?

Sorry, I wrote it wrong. I meant offsite.

If you want encryption enough, you can probably pay for a three-person business plan and just not set up the extra users. Looks like it would double your monthly subscription over the most expensive personal plan.

Its says: The latest security features will be available to all Dropbox Advanced, Business Plus, and Enterprise customers starting today.

Is dropbox advanced a business plan?

Advanced is their business offering - https://help.dropbox.com/plans/advanced-plan

Apple does offer this

I used to love Dropbox, then they limited devices and storage so much it was barely worth it, and spamming me with nag popups all day to upgrade because my storage was near full sealed the deal and I just started using OneDrive (not much better but it's integeated and convenient, probably going to just go foss with a home server eventually). Another sad downfall of a once good company.

They only limited devices for free accounts.

Paywalling existing free functionality is the most creatively bankrupt and fast way to get me to never buy your product.

I use Proton Drive [1], they offer e2ee but I agree with you: the Dropbox app experience is probably still the best.

[1] https://proton.me/drive

OK, so there is no fundamental obstacle for providing true e2ee.

Of course there isn't, but it limits efficiency and features. For example, you will miss all the fancy features Google Images does in cloud and user experience might be slower, since everything must be processed and downloaded on client side. Some level of metadata is always unencrypted.

That's trading one feature for a bunch of others. Users should have the choice of what features they think are important.

They typically do, by picking the product they wish to use.

It is very complicated to get this right from development standpoint. In true E2E, client must be "fat", kitchen sink and everything. Pretty sure Dropbox isn't like that right now. E2E is not a "feature", it is like a different paradigm of problem solving.

What I'd really like is for the encryption to be plugable and orthogonal to file syncing.

Ie: authentication with dropbox/proton/bittorrent concerns only that you pay your storage/ingest/egress bill, but is otherwise unprotected and in the clear. Encryption of the file payload and metadata as a "bring-your-own" — on device — stream cypher (and key derivation, key management). Key exchange and sharing among devices or users might then use yet another service or mechanism.

Pretty sure presenting all that in a slick easy to understand way has significant challenges, but it would be great to alleviate some of the dropbox as a single point of failure.

So kinda like how rclone does encrypted backends?

Of course not. It’s just storing bits at the end of the day. But storing seemingly random bits will always be more expensive than storing predictable bits, and this case is no exception: Proton is roughly 4x more expensive per bit than Dropbox.

Was the question whether or not it is hypothetically possible to provide an E2EE storage service? Surely you can apply your engineering chops here. Of course it isn’t. But there are trade-offs, as with literally any engineering choice.

Trying to understand some of the interplay here:

> threat actor had accessed data including ... certain authentication information such as API keys, OAuth tokens, and multi-factor authentication.

> If I have a Sign account linked to my Dropbox account, is my Dropbox account affected? No. Based on our investigation to date, we believe this incident was isolated to Dropbox Sign infrastructure, and did not impact any other Dropbox products.

If you linked your Dropbox account to a Sign account, wouldn't Sign have had an OAuth token (or similar) with permissions to access documents in Dropbox accounts? One imagines that leaked, if everything else did. Would they have been able to detect this as a distinct access pattern from someone, say, choosing a file to sign via the Sign interface?

Dropbox was breached also around 2012.

That was when i stopped using the cloud for storing personal stuff.

Fast forward a decade and i've more than had my fill of self hosting stuff, so a couple of years ago i went all in on the cloud again, though with a bit of a different approach.

Stuff that is not really sensitive is uploaded "as is". Yes, that includes our photos. While i don't want our photo library to be "public domain", there is nothing there of particular interest to anybody but my family and I.

For sensitive stuff i use Cryptomator to end to end encrypt data before uploading them to the cloud. It has desktop and mobile clients that allows me transparent access to my encrypted files on the go.

For this reason, I enabled E2E encryption for iCloud. Sure, if you are very paranoid, you can choose not to trust Apple, but E2E encryption on iCloud is seamless, and I haven't noticed a difference since enabling it.

I did the same, but i still use Cryptomator for stuff like sensitive documents and the sorts, much like i would have used an encrypted image before using cryptomator.

iCloud works great, and even if you trust Apple (which i do to some extent), your data is still only safe as long as nobody gains access to your devices. Once somebody has access to your devices, files are no longer encrypted.

The choice of Cryptomator was a convenience choice. I could have just as easliy encrypted files using GPG, LUKS, encrypted disk images or similar, but i would not have been able to access those directly from my phone/tablet in their cloud location, which is something i can do with Cryptomator.

For reference, i have about 4TB data in the cloud (~3.5TB photo library), and a 2GB Cryptomator vault, so it's not exactly the main driver of the operation :)

How do you sync the cryptomator vault safely, properly handling conflicts?

I use the regular iCloud sync method.

The Crytomator vault is personal, so i'm the only user, which means that conflicts are rather rare.

I've yet to experience synchronization conflicts with iCloud in my day to day usage, and i've been using iCloud since it was called MobileMe. I even ran with a local cache for a few years, and that never caused a problem either.

That was 12 years ago, react didn't exit, Windows was "8", Chrome was version 18, ...

I remember that day. It was the day I stopped using dropbox.

> For those who received or signed a document through Dropbox Sign, but never created an account, email addresses and names were also exposed.

So they also leaked data of people who are not their customers, and who never agreed to have their information collected.

I doubt that flies under the GDPR.

In the grand scheme of things, expecting your name and email address to really stay private is not all that reasonable. You probably gave them to the person who then used Dropbox Sign to send you a document. If you were really worried you could have used a throwaway account. The old saying is, once you tell someone, it's no longer a secret.

> In the grand scheme of things, expecting your name and email address to really stay private is not all that reasonable.

In the grand scheme of things, nothing matters and we’re all going to die. It’s been a while since I read the GDPR, but I don’t remember a section titled “personal data which is OK to leak because it doesn’t matter in the grand scheme of things *shrug emoji*”.

> You probably gave them to the person who then used Dropbox Sign to send you a document. If you were really worried you could have used a throwaway account.

Yes, you probably did. And that’s irrelevant. That data should’ve been deleted once it was no longer relevant. Almost no one goes around giving throwaway email accounts to acquaintances. Do you also suggest people have a throwaway phone number they give to friends and family, for when they upload it to a service like WhatsApp?

> In the grand scheme of things, nothing matters and we’re all going to die. It’s been a while since I read the GDPR, but I don’t remember a section titled “personal data which is OK to leak because it doesn’t matter in the grand scheme of things

Best comment on HN. Ever.

Both clever and informative on so many levels. It seems half of the HN crowd work in the Ad industry and never cease coming up with ridiculous excuses for why it's OK to abuse other people's PII. I was surprised to see there wasn't the usual gnawing of teeth this time, about the GDPR which tend to follow whenever that fine regulation is mentioned.

I am confused about Dropbox Sign's pricing model.

Why are they charging per-user? What exactly does that mean? A company will have one singular account and send documents to non-Dropbox affiliated entities, who aren't classified as users.

At least it's a hack this time, it's not like when they forgot to enable authentication and you could sign-in to any Dropbox just by entering the e-mail.

https://techcrunch.com/2011/06/20/dropbox-security-bug-made-...

It seems most billion dollar companies, are just Dave, hacking away on Node and dropping directly to production... :-)

Discussed on HN:

https://news.ycombinator.com/item?id=2678576 (46 comments)

And here I am, thinking that pushing bad CSS is going to end it all for me.

> We didn’t live up to that standard here, and we’re deeply sorry for the impact it caused our customers.

This might be the first time a large company has actually apologised and admitted some fault. Colour me shocked.

good reminder to enable 2fa on my dropbox account. Whoops.

Seems like they got the 2FA keys as well[0], so I'm not sure how useful this is in this context. 2FA seems it might be more useful where it's a different site and you've reused the password or had it phished, than in this case where the site is compromised.

I'm still unclear how much I'm impacted. I've used Dropbox Sign / HelloSign but always with my dropbox account. Resetting password and 2FA anyway, because why not.

[0]: They're asking people to reset the 2FA.

So, Dropbox failed to inform the affected customers?

Reply on news.ycombinator.com