Twitter says an attacker used its API to match usernames to phone numbers

https://www.zdnet.com/article/twitter-says-an-attacker-used-its-api-to-match-usernames-to-phone-numbers/

by spzx • 6 years ago

367 230 6 years ago

jraph• 6 years ago

I read the article and thought, "well, yes, the option that needed to be enabled on the account for the attack to work describes what the API did, what is the bug?"

I found the original notice from twitter [1] easier to understand (maybe change the URL of this post?) and it does not speak about a bug. Twitter did implement a change so that the attack cannot be done anymore though.

I did not understand the fix itself, it seems the API cannot be used for its intended use anymore?

[1] https://privacy.twitter.com/en/blog/2020/an-incident-impacti...

drewmol3• 6 years ago

The intended use was for a user to submit their contact data (phone book). Twitter's API would return a list of usernames matching those numbers for the purpose of requesting/notifying/suggesting potential friends (in exchange for their* data used to build a social graph/sell). Twitter patched/updated the API which means (the API probably returns a token or key or something that doesn't reveal the username now) if someone wants to submit a list of phone numbers to get their Twitter usernames they'll have to pay Twitter[0] or use a different "exploit".

* if someone has my phone number in their phonebook and gives it to Twitter - it becomes our data.

[0] https://business.twitter.com/en/help/overview/what-are-promo...

JaRail5• 6 years ago

The fix was to block the botnets that were scanning millions of numbers and ban the associated accounts. Likely that includes some ongoing threat detection as well. That'll at least prevent scammers from collecting one more account name/number to attempt exploiting.

It doesn't do anything against a targeted attack against someone who has chosen to be discoverable. That's just how search/discovery is intended to work.

sdan2• 6 years ago

Isn’t this old news? Thought this came out a few months ago.

boudin• 6 years ago

According to the article, Twitter discovered the problem on the 24th of December 2019.

sakisv• 6 years ago

From Twitter's statement:

People who did not have this setting enabled or do not have a phone number associated with their account were not exposed by this vulnerability.

This is a bit disingenuous, given that you can't really open an account unless you provide a phone number to "verify" it.

Edit for clarification:

As gojomo said below (https://news.ycombinator.com/item?id=22233612) you may not need to provide it during sign-up, but your new account is almost immediately locked for "suspicious activity" and you need to provide a phone to unlock.

kjaftaedi• 6 years ago

That might be the case now, but twitter didn't always require them.

I wouldn't be surprised if there are 10s of millions of accounts without phone numbers associated with them.

atomi• 6 years ago

They "requested" my phone number after the fact. And by "requested" I mean I wasn't exactly given a choice. I wasn't able to access my account until I provided a number. Of course all this was for "security" reasons. Personally I'd prefer to use Google authenticator anyway.

cmroanirgo• 6 years ago

I just checked the twitter signup form, which does have a phone input. But there's a toggle saying "use email instead".

So, no phone number is required.

gojomo2• 6 years ago

New accounts without an associated phone number tend to face a lock & challenge, for "suspicious activity" (even if they've never posted), which can only be reversed by adding a phone number.

So, Twitter is de facto requiring phone numbers on many more accounts than the initial sign-up flow might indicate – to the detriment of user privacy, & increasing the damage of compromises like this one.

newnewpdro• 6 years ago

They let you create an account without a phone number, and immediately afterwards lock the account until you provide one, for alleged "suspicious activity".

Try it.

LegitShady• 6 years ago

Disagree. If you make a Twitter account and then use it without a phone number it will quickly be locked to force you to prove you're human. It took less than 3 hours for mine. They want my phone number to unlock it enough to delete the account. No way.

raxxorrax2• 6 years ago

The whole phone number thingy for added security 2 factor auth has been quite the scam.

pingyong• 6 years ago

Why wouldn't you though, that's gotta be pretty juicy data. You can compare phone numbers across so many different databases now, makes profile creation 10x more efficient. Not really surprising that everyone wants your phone number badly these days.

Microsoft does the same thing btw. Was really fun for a friend of mine who registered a Microsoft account for mixer, forgot about, bought Halo, needed an MS account to log in, thought hey I already have one, and instantly got locked out because it didn't have a phone number.

switch007• 6 years ago

It's batshit crazy. But the PR campaigns/marketing by the companies that want your phone number for other reasons seems to have worked.

the8472• 6 years ago

Instead of providing a phone number you can also email support and complain about the account lock. But yeah, it's a pretty scummy bait and switch behavior.

notrandom• 6 years ago

I personally tried this. Pregnant silence.

rahuldottech• 6 years ago

I had to send at least six emails to get this to work. Six.

dicytea• 6 years ago

Does this vulnerability affect people who added a phone number but then removed them? Last time I tried, this method was effective for getting around the "suspicious activity" lock.

caseysoftware• 6 years ago

Even if you disconnect the number, they still keep it on file.

I have a small network of legitimate accounts that they've suspended a few times. In this last round of suspensions, I can't reset any of them with my phone numbers any more.

JaRail5• 6 years ago

No, it wouldn't work. It only works if people can discover you with the "find people you know from your address book" feature. A deleted number won't match. Or you can just turn it off in your discoverability settings.

jchw3• 6 years ago

Indeed: using email based sign up usually immediately triggers a suspension. It can take as little as a few minutes.

sf_rob• 6 years ago

My account was locked, I never sent a single tweet or even followed anyone, just refused to provide them more information about myself.

Polylactic_acid• 6 years ago

Same, looks like twitter just locks any account that isn't active enough for some reason.

drewmol3• 6 years ago

TL;DR

Twitter's data collection/friend matching feature used an API endpoint that returned usernames given phone numbers. A security researcher exposed it publicly, Twitter patched it (to just return a token or something). Twitter investigated and just released their findings "out of an abundance of caution and as a matter of principle." that it's clearly been "exploited" many times in the past. Twitter probably charges for the data returned by this "exploit". It doesn't look like the settings offered stop Twitter from selling this "exploit" as a service for "promotional" content.

It's seems strange not care that Twitter sells your username but care they also accidently gave it out for free in the past.

kingosticks• 6 years ago

Any chance this means they'll get rid of their popup that asks for my phone number everytime I visit. You only have to refresh the page to get rid of it but it is annoying. This incident shows they don't know what they are doing and don't respect their user's data.

_Understated_• 6 years ago

Twitter did not clarify who these third-parties were, but it did say that some of the IP addresses used in these API exploitation attempts had ties to state-sponsored actors, a term used to described either government intelligence agencies, or third-party hacking groups that benefit from a government's backing.

Can someone explain this to me please? Are "state-sponsored hackers" this foolish to use the same IP addresses as previous, known IP's used in hacks?

Or is this just the current "because terrorism / because pedophiles" used to cover incompetence?

I don't get it...

BurnGpuBurn• 6 years ago

Yeah I never believe the "state-sponsored" hackers claim, or any claim to the location of them, until those hackers get caught and convicted based on real evidence. It's basically guesswork anyway. And certainly to a company like Twitter who doesn't even have the capabilities to really investigate a hack, compared to say the NSA, CIA or similar spooks.

meowface• 6 years ago

I've been involved in research of this nature, though not specifically attributing APTs. Think of it like old school detective work: every crime and every criminal leaves traces, including the traces of the ways they attempt to prevent being traced. This sometimes also includes attempts to impersonate other entities ("false flags"). No matter how many layers of indirection an attacker uses, there's going to be at least one thread to pull on.

There's no equivalent to DNA testing, but sometimes you can have pretty high confidence in an attribution. To be clear, this goes incredibly far beyond looking at IP address geolocation or whatever. That's less than 1% of what you're looking at. That'd be like police assuming a death threat was signed with someone's real name.

There's no way of knowing exactly what they identified or how they did it or if they got it right. I wish more companies would release such information and how they conducted the entire analysis (some do), though I understand that may not be possible due to legal and counter-intelligence reasons.

buboard2• 6 years ago

phone numbers are better than ips for surveillance. they follow you everywhere.

Scoundreller• 6 years ago

I eagerly look forward to a phone-number free world.

Would help a lot with global mobility.

rezeroed• 6 years ago

Why on earth would you give twitter your phone number!? It's an ad company. Why on earth would you give an ad company your phone number?!

arminiusreturns3• 6 years ago

Went on a tweet storm a few months ago. Twitter locked my account and forced me to give my phone number. I started getting spam calls at a level I didn't before (may be coincidence but am very tight about that sort of thing, I don't even give my grocery store my #) and I knew, just knew that at some point, this very thing would happen.

Combine that with the story that the Saudi's had infiltrated twitter and were spying on users, especially in light of how they treat their opponents (Kashoggi), when do we stop supporting companies that do these obviously poor practices?

vorpalhex• 6 years ago

when do we stop supporting companies that do these obviously poor practices?

Well, you just indicated you chose to continue supporting this company with the poor practice above. What would make you switch away from them? Clearly the spam calls weren't enough.

arminiusreturns3• 6 years ago

It's a complicated issue. I am very privacy focused, the kind of person that doesn't do facebook, burns accounts on different forums regularly, etc, but I have to admit I enjoyed the information I got out of twitter while not enjoying some of their recent changes.

Since the spam calls and the phone link in though, I have already changed my twitter-name and lost all followers, and since then I pretty much stopped tweeting. Haven't logged in in at least a month now.

The main problem with adoption of an alternative is that I was using it to keep up with the kinds of people that aren't necessarily going to move to an alternative until it reaches some sort of critical mass. My RSS feeds are already full enough without having to add a bunch of random single person blogs to keep up with, so I'm not sure to be honest. Twitter was my main compromise to stay more socially connected with a wider array of people and it's hard to let go of that.

Despite my desire for good federated and open source social networking, it isn't quite there yet, and so for the time being the one social outlet alternative I see glimmers of hope in is WT.Social.

Jamwinner• 6 years ago

Exactly. These people are petting the dog after it attacks their kid, oblivious to the training they are offering and reinforcing. We as a collective are just teaching big tech how to more effectively enslave us for profit.

scottlocklin• 6 years ago

Saudi problem seems more severe! Call me crazy!

Not that I use twitter; people who get on the thing seem to have some bizarro Stockholm syndrome.

Forgivenessizer2• 6 years ago

The average user has no idea what their phone is capable of, and how little effort it takes to spy on them. They think spying on them can only be accomplished by elite teams like on CSI:Miami, or that only some weirdo antisocial dork can do it, but only upon communion with the devil, at a crossroads, at the first full moon.

jrochkind13• 6 years ago

The endpoint matches phone numbers to Twitter accounts for those people who have enabled the “Let people who have your phone number find you on Twitter” option and who have a phone number associated with their Twitter account.

I don't recall hearing about this option. I followed the link they helpfully included[1] to see if I had it set.

I found that I DID have "Let people who have your phone number find you on Twitter" checked. But did NOT have "Let people who have your email address find you on Twitter" checked.

It's possible I actually chose that at some point, for some reason decided I was okay with "by phone number", but not "by email". But that doesn't sound like me, I'm wondering if I unchecked the "email address" one at some point when the "phone number" one didn't exist; then they later added the "phone number" one defaulted to on?

I am guessing they intend to default all of these to on (opt-out rather than opt-in), cause few people would take the trouble to go and opt-in even if they didn't mind or would like it.

But... you know. Anyway, I've unchecked both of them now.

I don't entirely understand the vulnerability, it sounds like it was "letting people who have your phone number find you on Twitter" just as advertised. "we immediately made a number of changes to this endpoint so that it could no longer return specific account names in response to queries." OK, so... you can't use the API to do that anymore, but can still use the twitter web app directly? I mean, it says right there you are letting people who know your phone number find you on twitter, which I would assume means find your account name.

It kind of sounds like they realized this whole feature was privacy-violating, or would be perceived as such, but they haven't gotten rid of the feature... I'm confused what they considered the vulnerability and what they changed or didn't, and to what extent usernames and phone numbers can still be matched by a third party on twitter.

[1] https://twitter.com/settings/contacts

arkadiyt• 6 years ago

You can also delete your phone number completely - there's no real reason for Twitter to have it, especially now that it's not required for 2fa.

larrik• 6 years ago

Didn't you use to tweet via SMS? I assume that's still an option? Seems like a valid reason for them to have it.

dylz• 6 years ago

You will receive account suspensions shortly after / days after removing it, at least in my experience.

EGreg2• 6 years ago

Honestly, there is a world of difference between having an API to do things in bulk and only allowing rate-limited clients to do something.

Both require authentication (although new court rulings may technically be outlawing all charging and quotas for APIs!)

But the API has far more permissive bulk actions. Of course, with a botnet and enough time and effort one could execute a sybil attack to circumvent any per-account quotas, and use per-resource quotas to launch a DDOS attack on some resource to any non-authenticated parties.

I wish there was - service to prevent sybil attacks somehow. Just make it exponentially more expensive to create multiple identities / accounts on networks. Has anyone got links to papers or projects or anything in that direction? It would be hugely valuable.

PS: Twitter and other startups don’t particularly care about sybil attacks and fake users when they are growing, it helps them “innocently” report great user numbers to VCs. So they don’t spend much effort preventing sleeper bots from joining in the network’s growth phase.

jrochkind13• 6 years ago

a world of difference between having an API to do things in bulk and only allowing rate-limited clients to do something.

Sure, the difference you speak of is only and exactly if the rate-limiting on your API is different than on the other rate-limited (web?) clients, right?

It doesn't have to be, but it often is, for various reasons intentional or accidental. Making the rate limiting the same might be another way to fix the "vulnerability" then? It depends on what they consider the vulnerability exactly; if you don't know what it is you consider the problem, it's hard to fix it, or for you or anyone else to judge if you've fixed it! I find their statement to be vague on what the problem was exactly, as above.

jsnell3• 6 years ago

(although new court rulings may technically be outlawing all charging and quotas for APIs!)

That seems quite hard to believe. Do you have a link?

tzs• 6 years ago

It's possible I actually chose that at some point, for some reason decided I was okay with "by phone number", but not "by email". But that doesn't sound like me, I'm wondering if I unchecked the "email address" one at some point when the "phone number" one didn't exist; then they later added the "phone number" one defaulted to on?

I looked at mine, which I'm sure I've never touched before because I never cared about Twitter settings. As with my Facebook account, my Twitter account was mostly just created to get an acceptable name in case someday I actually wanted a serious social media presence.

Both are unchecked. The account was created in early 2008.

fernandotakai• 6 years ago

yeah, same. account created in oct 2007, never checked and i have everything turned off.

nyuszika7h• 6 years ago

If you’re in the EU they were likely disabled in 2018 as part of the GDPR prompt.

segmondy• 6 years ago

I have the inverse, I never did check it myself. That I can assure you of. I don't care for anyone finding me on social media.

rcthompson2• 6 years ago

Based on the "large network of fake accounts", I'm guessing the attackers were doing something to effectively query every possible phone number and associate an account to each one.

ramses0• 6 years ago

@fake_twitter_account_212_111_xxxx w/ a phonebook contact list of "212-111-0000" => "212-111-9999". Lather, rinse, repeat. You'd need ~10M accounts w/ ~1000 phone numbers in each, and that can be reduced by some percentage if you know how U.S. phone numbers are assigned (ie: don't check for xxx_555_xxxx numbers, prefer highly populated prefixes, etc.)

Good thing they SUSPENDED those accounts! /s

deft• 6 years ago

What happened: Twitter asks users on sign up to scan their contacts (read: steal and upload them). If you say no, twitter asks again and again every day / every login until you finally allow it to. Twitter builds a huge and unnecessary db of users and phone numbers, as well as non-users IDs tied to phone numbers. Someone uses an API to steal this info that in most cases twitter only collected by tricking their users / forcing it.

Anyone affected by this should be suing twitter for even collecting this information! My friend can give away my phone number because of this data collection.

fireattack3• 6 years ago

If you say no, twitter asks again and again every day / every login until you finally allow it to.

Any proof about this claim? I use Twitter on Android and web frequently and I only refuse such request once or twice.

Bottom line, it doesn't "ask again and again every day".

throwiay987• 6 years ago

Consider yourself lucky, any account i create without a phone is immediately flagged\blocked and if i do use mine(personal), i get asked to add permissions like the parent said every single time.

nacs• 6 years ago

If you use the web client, they have a header that asks for your phone number repeatedly until you give it.

zippergz• 6 years ago

I've been using Twitter daily pretty much continuously since 2008 and I don't remember ever being prompted to upload contacts. I can believe it has happened at some point, but it certainly doesn't repeatedly ask me. I use the web interface and the first-party iOS app (though over the years I have also used various third-party apps on both iOS and macOS).

Zenst• 6 years ago

Anyone affected by this should be suing twitter for even collecting this information! My friend can give away my phone number because of this data collection.

Given the ramifications on leaking Name with phone number of people who didn't agree directly anything with Twitter and just had there contact details trawled by any of their friends signing up. Not good as with that, hijacking phone numbers has been done many ways and times, even the CEO of Twitter had that stunt pulled upon him. What with 2FA for many being a text message sent to your phone number. The ramifications of this could be bigger than they first appear and remember. They only found this, how long has this been open to such abuse. So anybody who had their phone number hijacked in X period of time, this `might` be a possible explanation in some of those instances.

Legally - no idea how this will pan out, but certainly not be the last we read about this.

xorfish• 6 years ago

You can also match phone numbers and Instagram accounts

u801e4• 6 years ago

What with 2FA for many being a text message sent to your phone number

We should also sue companies who continue to use SMS as part of their 2FA system and/or for account recovery.

RKearney• 6 years ago

A trick I found to stop this nonsense is, at least on iOS, answer yes to the Application's custom dialog to ask permission. This will then invoke the iOS security dialog where you can click "No" and never be asked again.

Generally what I see happening is apps will ask the user if it's okay, and only when the user says yes will they execute the necessary system call to request access. In iOS at least, if a user clicks No the app can never prompt for that permission ever again. Until the app makes this formal request to the operating system, it does not show up under privacy (as the app had never asked for it in the first place).

lonelappde2• 6 years ago

What does Apple allow that for App Store apls? That's obvious circumvention of iOS's privacy control regime.

vincentmarle• 6 years ago

Your friends/family probably won’t do this, so your phone number is going to be shared with Twitter anyways.

diebeforei4854• 6 years ago

Ideally, iOS would have an option to say "always deny Contacts access and never bring up a dialog again".

I don't share my contacts with any app, and I hate being asked again and again for every single new app. No means no.

ngvrnd• 6 years ago

this worked for me also.

hk__2• 6 years ago

Note this trick is also generalizable to apps/websites asking for notification permissions.

russum• 6 years ago

I've had apps ask me to go to system settings myself to enable some permissions because I've disabled it via the said OS prompt.

loco5niner• 6 years ago

Similar to being asked "do you like this app?" If you say "Yes", you are directed to rate it, if "No", you are not.

amluto• 6 years ago

Apple could nip this in the bud: don’t allow apps to read a full contact list at all. Use a contact picker when needed.

twodave3• 6 years ago

This certainly would break plenty of valid use cases for a feature like this. More likely they ought to have policy in their developer docs to scope reasonable uses of the full contact list and start rejecting updates for applications that violate the new rule.

what_ever3• 6 years ago

How will apps like Whatsapp work then?

rchaud2• 6 years ago

It's for this reason that I use PWAs wherever possible. Right now I'm using it for Twitter and Uber. Tired of turning off permissions and then having to do it again when apps auto-update and restore the original permissions.

drewmol3• 6 years ago

Anyone affected by this should be suing twitter for even collecting this information! My friend can give away my phone number because of this data collection.

If you made some agreement as to how your friend could use your phone number and 'sharing with Twitter' is a violation then you could sue them I suppose. Annoying as this data collection is, labeling information about you as only yours is incorrect, it's your friends and Twitters's (and Google/FB/AMZ/etc.) information too.

app4soft• 6 years ago

Quick & dirty fix: never use built-in/default apps for storing contacts list on your devices.

codedokode2• 6 years ago

That's not the only way Twitter uses to collect phone numbers. It can arbitrarily block your account and require to confirm a phone number to unblock it (under excuse of "better security"). How disclosing your phone number helps being safer I don't understand.

Now those collected and leaked phone numbers will be available not only to Twitter and US government but to anyone wishing to buy them from hackers.

mlindner• 6 years ago

Twitter has never asked to access my contacts before. Where are you seeing this?

numpad0• 6 years ago

I think they’re selecting target demographic to do this, because for e.g. Japanese it means having Twitter account associated with their real names means they’ll be laughed at from everyone close to(maybe 25% literal) death. Same for follow suggestions based on IP.

TheLastSamurai• 6 years ago

Yes, totally. Thieving from a thief logic applies here.

rhegart• 6 years ago

I just quit when they finally said I had to to log in.

sohkamyung• 6 years ago

Twitter asks users on sign up to scan their contacts

To be clear, this applies to the Twitter app for iOS and Android, correct?

I exclusively use the Twitter web interface (even on my Android phone) and I have never been asked this.

markdown• 6 years ago

In some countries (including mine), all sim cards/phone numbers are registered to an individual, so this is a pretty big deal.

raxxorrax2• 6 years ago

Twitter should be seen as an asylum if you ask me. But yes, if they leaked numbers from third parties not involved in Twitter at all, there should be severe legal consequences.

But I doubt there is much incentive to even create a legislative basis for such transgressions. Complicated topic to be fair, but we will only see improvements if there are severe penalties for "loosing" data. Since no system is safe, there is only the alternative left not to collect info you do not need.

busterarm• 6 years ago

So I guess Twitter applied for a technology embargo exemption to Iran?

I mean, I guess that's been public knowledge already that they serve there, but the overwhelming majority of public companies block the IP space of every country on the embargo list.

I'd think that serving Iran right now would be fairly politically untenable

xxpor• 6 years ago

Most of Iran's leadership have active twitter accounts, so I'd have to guess so.

milofeynman2• 6 years ago

I swear I saw someone mention this a month or two ago in HN comments. They said that they believed Twitter's API was being used to unmask accounts by state actors. I can't find the original article now.

jsnell3• 6 years ago

You're thinking of https://news.ycombinator.com/item?id=21873229

That was slightly different, since at that time the only information we had that this unethical "security researcher" had exploited the bug for months on billions of phone numbers and only disclosed it once Twitter blocked them.

This announcement is different in that Twitter appear to be saying that this was being abused by other actors as well.

milofeynman2• 6 years ago

That was exactly the comment. Thank you! It sounds like everyone and their mother was exploiting the API based on today's post. Thanks again.

TylerE• 6 years ago

It's a phone number, not your bank account.

It's public information.

Do you want to sue the phone telcos for publishing the phone book?

XMPPwocky• 6 years ago

What's your phone number?

I might call you and check- and check for VOIP numbers, too, so no fakes.

techsupporter• 6 years ago

check for VOIP numbers, too, so no fakes

Ah yes, continuing the fiction that anyone who uses a VoIP service must be a fraudster with a faked phone number.

Just another in the long list of if you are not using Google or Microsoft e-mail and AT&T or Verizon or T-Mobile or Sprint postpaid mobile phone service, you're obviously up to no good and deserve whatever "anti-fraud" you get.

Jestar342• 6 years ago

It's public information.

No, it isn't.

stuff4ben• 6 years ago

you have one of those private, encrypted phone numbers that prevents unauthorized usage? Get over yourself, it's public information.

BoorishBears2• 6 years ago

Eh, it pretty much is. At least in the US

I have a pretty unique name, you can search my first name + "voter registration" and get my address, phone number, and birthdate

Even if my name was common, it'd still be out there

mstolpm• 6 years ago

No, its only public if you choose to disclose it. Phone numbers are PII (personal identifying information) in regards to the GDPR.

tripa2• 6 years ago

Sorry for the slight pedantry, but PII is some American thing. GDPR deals with "personal data".

It's playing on words until you find out the PII definition isn't the one that's used to settle GDPR claims.

RL_Quine• 6 years ago

What’s your phone number? If it’s public you don’t mind sharing it. My address book is filled with people who would be very sad if that were made public.

ckastner• 6 years ago

It's not public information, and it's considered identity-tied enough to be used in many forms of two-factor identification.

moron4hire• 6 years ago

It is public information, and that's why it's ludicrous that it's used for two-factor authentication.

Two-factor authentication is a dumb solution to a real problem. The problem should be properly solved, rather than hacked around with stupid solutions like "sending notifications to accounts that can easily be spoofed by willful actors".

ghaff• 6 years ago

Private vs. public isn't a fine-grained enough distinction. It's not private in the sense that most people give it out to lots of people so that they can be contacted. (Of course, in the case of landlines, they're mostly listed in a public directory somewhere but I assume we're talking mobile here.)

BTW, you bank account number is the same way if you write checks.

So they're not private in the way that some data (like health information) that you're only going to share very selectively is private. But it's mostly not public in the sense that you'll likely put it online unless maybe it's a business phone.

jchw3• 6 years ago

Your identity is not public information on Twitter. Posting someone’s phone number and Twitter handle, if they did not explicitly share it anywhere, would be doxing, against almost any site ToS, and potentially even illegal.

sdan2• 6 years ago

Are there any legal repercussions against doxxing

glofish• 6 years ago

pff, considering that a large number of two factor authentication protocols send you SMS your phone number might just as well be your bank account

throwaway55554• 6 years ago

Just because it's public doesn't mean it should be shared with everyone.

You wouldn't type your number into a HN comment, would you? Probably not because you know exactly what would happen.

AlexandrB• 6 years ago

It may be public, but I don't see you posting your phone number on HN. Perhaps that's because you don't want everyone in the world to have it? Doesn't seem like an unreasonable expectation to me.

zepolen• 6 years ago

What's your phone number?

mikey_p• 6 years ago

The deepest irony of all this is that they require phone numbers to verify accounts, which should cut down on fake accounts, yet they had a large amount of fake accounts using this very feature, which means verifying with a phone number may not be super effective anyway...

kwijibob• 6 years ago

I factory reset my phone so my lost my gauth 2fa for Twitter. I'm locked out now.

I cannot get Twitter to let me back in even though I can verify my email and phone SMS.

I didn't make a backup code because I assumed I could use email/SMS in this situation. It seems not.

So another smaller irony is that you cannot make valid use of your linked phone number that they nag you for.

mLuby• 6 years ago

Why is "impacting" better than "affecting?"

dghughes• 6 years ago

For starters impact is a noun and affect is a verb.

It's probably textbook risk analysis lingo, an impact is measurable but an affect is not.

Usually an impact scale is created to define what impact level 5 would involve versus impact 1. It's still arbitrary but more configurable than affect.

Just my two cents, no guarantee.

simonebrunozzi• 6 years ago

Class action?

markovbot2• 6 years ago

Unlikely to succeed. This sort of invasive, drag-net data collection without user knowledge or consent is considered standard practice.

All twitter users "agreed" to it when they created their account (via the legal fiction that humans read and agree to terms of service)

cmcd• 6 years ago

I didn't create a twitter account but my information could have been leaked via this process.

jdc• 6 years ago

I'm not convinced that "standard practice" is a sufficient legal defense.

GrumpyNl• 6 years ago

One of the reasons i never installed the twitter app. Will keep using the web page.

diebeforei4854• 6 years ago

They should not allow phone number -> handle lookups. That is quite creepy.

A much more privacy-respecting method would be to only allow lookups if both parties have each other added.

thiagomgd2• 6 years ago

I was already thinking of deleting my twitter account. This is just an extra incentive

dickjocke• 6 years ago

I was rejected with no explanation from a Twitter API key, despite it being for a real account that must appear very normal in every respect.

I think it's kind of funny that they are so draconian with hobbyists and people making toys, but that any motivated bad actor can probably access most of the same endpoints and services by virtue of the fact that they have to be accessible for people to use Twitter.

daenz• 6 years ago

At some point we'll realize that privacy invasive policies are a huge security liability, right?

rewq43212• 6 years ago

I was amazed when I found out about this "trick" a year or two ago. It basically means that if you've used your personal email or phone number to create an "anonymous" twitter handle (e.g. a whistleblower, leaker, etc.), then it's not anonymous at all.

Someone can just put batches of emails into their gmail account (e.g. journalists' public emails, their employees' emails, other suspects), then use the Twitter contacts-import functionality to import those emails and match them up with Twitter account handles. It's insane.

I first saw people explaining how to do this on Quora a year or two ago, but here's another explanation that was posted just a few days before this announcement: https://www.quora.com/How-228/answer/William-Boyd-181

Twitter MUST have known about this loophole for many years. It's nigh on impossible that they are that incompetent, so, as far as I can see, they were just ignoring the loophole because they didn't want to slow down their growth by removing the feature. As with all social networks, the most important factor in keeping users is to quickly get them a network of followers and followees.

EDIT:

"People who did not have this setting enabled or do not have a phone number associated with their account were not exposed by this vulnerability," Twitter said.

This spokesperson is extremely sneaky. They completely neglect to mention that the "let others find me by email" is checked by default, and so we can only assume that anyone who has a publicly scrape-able email somewhere (basically everyone, because you've got to count all the leaked databases too - see: haveibeenpwned.com) has had their Twitter handle linked to that email. Atheist bloggers in Saudi Arabia, whistleblowers in the US, opposition activists in Russia, and so on - all potentially fucked over (past tense) by this.

And while I'm ranting: What's worse is that they apparently haven't disabled that API. They've just removed a few big crawler swarms. But the thing is, Russia / Saudi Arabia / etc. probably have narrowed their suspects down to 500 (or so) emails anyway, so they can discover the heretic/activist in a SINGLE API REQUEST! So Twitter has done nothing to fix this loophole.

yomly• 6 years ago

Yes this is the thing everyone should be talking about. Think of any of the bigger Twitter posters on Hong Kong. If anyone of the ring leaders didn't decouple their twitter handle from everything else they will have a giant bullseye painted on them by CCP

C4stor• 6 years ago

The first thing twitter proposes when you create an account : "Do you want to match emails and phone numbers to account".

In this thread : "How can it be possible to match emails and phone numbers to accounts?"

It's not a loophole, it's a feature.

It's in the TOS before you sign up : "Twitter also uses your contact information to market to you as your country’s laws allow, and to help others find your account if your settings permit, including through third-party services and client applications."

How can someone then not realize this is a possibility ? At what moment can someone start to even begin to think twitter is a safe place for endangered people ? It's an ad company, what do you expect really ?

rewq43212• 6 years ago

The fact that you're citing the TOS is not exactly helping your case, since it's well known that basically no one reads those. I'm not as concerned about techy people as I am about the average person's understanding of their identity privacy on Twitter.

But even as a techy person I was surprised by how easy it is for a random person to link millions of identities. And I'm obviously not alone given that this post made it to the front page. So when you say "what do you expect really?" - well, most people expect that a random person can't discover their email from their twitter handle. I think that's a completely fair expectation, and people should rightly be concerned about this "feature". Posts like this should be upvoted, because a lot of people aren't aware.

Your incredulity here tends to come across as "it's in the TOS, you're all pretty ignorant, I knew about this all along." which isn't all that helpful, even if it's all true.

Forgivenessizer2• 6 years ago

We need to nationalize Twitter & FB & Google, so we can get some decent privacy options. Without this, it will be impossible for us to secure friends and family we care about. Sure nerds can secure things themselves, but that's totally insufficient. Until then, things will only get worse.

3fe9a03ccd14ca5• 6 years ago

Twitter could go a long way in solving this issue by not requiring a phone number for an account. While you don’t need one to sign up, after some short period of time you’ll be locked out if you don’t provide one.

spoondan• 6 years ago

It’s interesting to me that these kinds of things are not catalogued and advertised like other vulnerabilities. This is an exploitable information leak using an endpoint that many other services likely have.

exabrial• 6 years ago

I don't even feel sorry for them. Many many times over, industry experts told people: SMS is NOT 2FA and should not be used as such. Great to see karma served, and I look forward to U2F or Webautn on my twitter account soon.

rchaud2• 6 years ago

What's there to feel sorry about? Twitter isn't facing any regulatory scrutiny over this, let alone possible fines.

lowdose• 6 years ago

Kind of ironic Twitter can't protect data theft but spends considerable amount of resources to detect Deep Fakes.

krapp• 6 years ago

How is that ironic, those are two entirely different issues.

stebann• 6 years ago

Someone have mentioned spam after being forced to provide his/her phone number to Twitter, and I have known of similar cases in 2019. I also remember a case where the police matched a twitter handle to a phone number and proceeded to arrest a guy who have been a strong activist against electronic vote. So I can conclude that this bug was well known at the beginnings of 2019.

est• 6 years ago

this "bug" made hundreds of thousands Chinese activists' account "disappear". Sad.

geogriffin• 6 years ago

After our investigation, we immediately made a number of changes to this endpoint so that it could no longer return specific account names in response to queries.

Does anyone know what this actually means? If the contact discovery API doesn't return a username, what does it do? If the answer is that it returns a user ID now instead of username, then presumably that can then be freely queried for the corresponding username..

typeformer• 6 years ago

Wtf

baybal2• 6 years ago

https://news.ycombinator.com/item?id=21748137

From 2 months ago:

Basically Twitter got pwned big time, and now denies it because GDPR will ruin them if breach is proven. Here is what Doubi's online followers figured:
State security got all phone numbers used for Twitter phone verification up to May 2019 and possibly till July.
Twitter haphazardly closed the breach in complete secrecy.
API hole explanation is excluded as people with 100% private accs got police visits.
People with foreign SIM cards also got into trouble. So the explanation that China compromised Twitter's SMS providers is also excluded, as its improbable that they did it in 4+ countries.
2016 breach is also out of question.
The only explanation is that they got hold on a big piece of their user DB, or, worse, they have an active infiltrator in Twitter, or Twitter voluntarily cooperated.
https://mobile.twitter.com/robert_spalding/status/1134797195....
https://amp.ft.com/content/afd44222-5c34-11e9-9dde-7aedca0a0....

gorgoiler• 6 years ago

Nothing in the article about collaboration with law enforcement or national security.

Some amount of liability on Twitter’s part in this is palpable, but this is also a criminal act on the part of the attacker who should accordingly be brought to justice, or at least an attempt should be made to do so.

If this is happening with law enforcement agencies then I feel like tech companies usually say so. Twitter’s statement says they are “releasing the details” but there’s no mention of law enforcement or state department involvement.

If the press release is meant to achieve this engagement publicly, then there are no actual “details” in it for example, no link to a list of IP addresses, twitter accounts, and times at which the endpoint was accessed!

Thats a bit flippant of course but perhaps there is actually a way they could have released some of those details: ASNs, days of the attack, some other aggregation?

In any case, some reassurance from Twitter that this is being followed up on by a government agency would be good to see.

swadizand• 6 years ago

Attacker what? He, Ibrahim Balic, is a security researcher; but when it comes to Twitter, they are stubborn claiming the bug was a feature. See what "attacker" says:

https://youtu.be/CuiGKv_nx7o

buboard2• 6 years ago

There should not be an app permission to export contacts list in the first place. If an app needs your contacts, there should be a way to export them offline and upload the contacts file. If a user is not technically adept to do that, they are clearly also not adept to judge the ramifications of pressing the "allow" button on the contacts permission dialog.

Twitter says an attacker used its API to match usernames to phone numbers

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