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Bruteforcing the phone number of any Google user

zerof1l

This article highlights something interesting... it is quite common to get at least one /64 IPv6 block from a hosting provider or ISP. Yet most of the rate-limiting and IP blocking is done for a single IP. Sounds like when dealing with IPv6, an entire block of /64 should be rate-limited or blocked.

vladvasiliu

Even companies which not only should know better, but are actually paid to handle things like this get it hilariously wrong.

The company I work for is a client of a big-ass CDN you've heard of (not the one whose ceo hangs around these parts). Yet, they somehow think it's fine to notify me of "new connections from an unusual IP" when I connect from the same /64 block of ipv6.

bscphil

I'd be rather surprised if IPv6 hasn't done some damage to the idea of IP blocking on the whole. It's possible, even as a residential Internet user, to request a /56 or /48 automatically with DHCPv6 Prefix Delegation. I have a /56 with Comcast. That's potentially up to 65536 /64 blocks, just from a residential user, so if you're going to attempt IP filtering for IPv6, it's got to be a lot smarter than swapping out your single-IP blocking for /64 blocking.

edelbitter

It actually makes things a easier for both blocking and allocating (e.g. VPS hoster) side.

Once the "oh no, we can't afford that many unique allocations" excuse is away, algorithms that enforce quotas for every prefix size at the same time (with no excuses for CGNAT weirdness) stop being too ruthless.

You can distribute your addresses as needed, and I can track successful and failing attempts - at whatever distribution scheme you use. E.g. group your "unverified" or "trial" accounts at a larger prefix size, so they get each other blocked - but not your paying customers.

Guvante

It is already pretty common to start with IP blocking but upgrade to blocks when the bad behavior continues.

Assuming a /64 as a starting point is an easy win and bumping it up with repeat offenders seems pretty easy in the grand scheme of things.

bigstrat2003

How are you getting a /56 from Comcast? I can only request up to a /60 from them, any larger and I get a /60 rather than whatever I requested.

stackskipton

Rate limiting on /64 for IPv6 is well known and I know Google does it for other services. Sounds like this was not properly updated when they put IPv6 into play.

markasoftware

[BuyVM](https://my.frantech.ca/cart.php?gid=37), a popular host for shady operators, gives a /48 even with their cheapest plans ($2/month, though only $7/month is in stock right now)

madars

Missing context: BuyVM is a legitimate business, popular with hobbyists, that has features that are hard to get elsewhere (e.g., BGP sessions). They do take a pro-free speech stance, but they are a far cry from bulletproof hosting ("shady operators"). An imperfect comparison at a massively bigger scale would be Cloudflare's prominence in certain communities.

benlivengood

I had assumed that most people would block by /64. Probably safest to count distinct abusive/noisy IPv6s per /64 and block/throttle when it hits a threshold.

Ratio of abuse traffic per IPv6 from a /64 might also make a good threshold.

AtomicByte

Yes that does happen to be what is commonly done

punnerud

What if the user only get one address, how to separate the two? Seems like a need to share if a larger block (providor) is handing out based on blocks or single addresses…

stackskipton

Say what? IPv6 was designed that first 64 bits are network, last 64 bit are host.

Since /64 is smallest network in IPv6 and because of that most providers hand out /64 when you ask for IPv6 public address because A) Most Rate Limiting uses /64 and B) IPv6 has so many IPs, no one cares.

Vultr has at least one /32 I was able to find (2001:19F0::/32) which if you cut that into /64 comes out ~4.2 Billion different networks or same amount of IPv4 address that exist.

ARIN will hand anyone who asks a /48 IPv6 subnet which 65,536 unique networks and getting larger prefix is not hard.

growse

> Since /64 is smallest network in IPv6

A /64 is not the smallest network in IPv6. Nothing stops you having a /112 or a /126 or whatever you like.

It is the only network size on which SLAAC works however, so it's a good choice for lan sizes.

bsamuels

IP rate limiting hasn't been a serious misuse prevention tool for 15-20 years

demosthanos

Can you elaborate? As one tool among many it seems to me to be a perfectly serviceable tool in the toolbox, with a sufficiently high rate limit to account for shared IPs.

VladVladikoff

I’m mostly impressed that he can throw 40k requests per second at a server for a prolonged period and not somehow spike the resources enough to set off some alarms.

kevindamm

it is possible that it did throw an alarm but the behavior ceased soon enough afterwards that it didn't escalate to alert-level paging, or that -- even if it did -- those resources were back to normal within a few minutes that it took to open laptop, password password OTP, link-following and graph-referencing annnd oh it's already coming back down before the status update is drafted.

And 40kqps isn't really much at the scale of Focus (or most of Google's APIs) so I could easily see it going under the radar, especially each using different IP addrs and with IPv6 across /64.

The gap worth noticing here isn't monitoring, though, it's the zero rate limiting on js_disabled flow using a token borrowed from an earlier js enabled flow.

atum47

I did something similar way back when I was trying to find the phone number for a person, using Facebook.

When recovering a password Facebook would give you most of the digits of the phone number, so I wrote them down in a vcard file and imported it on my phone to just look at the pictures. It worked surprisingly good.

VladVladikoff

There is also a similar hole with Google profile photos and other Google apps. For example if you see a review by John Smith on Google maps, you add emails on Google Hangouts, guess a bunch of variations like johnsmith@gmail.com, smithjohn@gmail.com etc and see the profile photos to compare the match.

dheera

This is why I don't use a real phone number with any of these services. They don't need my phone number to operate either.

shwouchk

g has been demanding a valid phone for years, as have most other major providers. if you lose the number you sign up with, you can potentially get locked out of the account. whats your mo?

mystifyingpoi

Not sure how it looks in USA, but in EU you can get a prepaid SIM card for $2 and use it forever for cases like this. You'll probably have to top it up with another $1-2 if used sparingly, but that's the price of such separation.

helsinki

These bug bounties pay peanuts. Sad.

RankingMember

They're only hanging themselves by cutting the bounties like this.

jeffbee

It must be a daunting chore to maintain all the legacy pages. The amount of now-years-old stuff that long-standing sites have to maintain, or choose to maintain, is shockingly high, and testing the combination of all that stuff is impossible.

If you want an example of how diverse in age these apps are, dig around in the Gmail settings panel. Eventually you will land on a popup that uses the original Gmail look and feel, from 2004.

xivzgrev

Bug bounty program appears to be an efficient spend. For a few thousand dollars they mobilize unpaid people looking for extreme edge cases and then surface these issues. It would’ve cost way more to pay an employee to search for this.

mmsc

Depends on the company. Also It can be a good way to say to management, "look, this old deprecated shit needs to be replaced because it's insecure; maintenance is a security issue"

paxys

Which is exactly why companies are aggressive about deprecating old products and services. "But why can't they just leave them running and not touch it?" Because every such service eventually becomes a security hole. The only secure code is no code.

okanat

While your argument seems to make sense on the surface, it fails in deeper inspection.

What security implications did Google Reader have? I do understand keeping older APIs and endpoints for authentication and authorization are indeed dangerous. However, if your architecture causes the mere clients of those authorization infra to be exploited, I think the problem isn't keeping the products running. You designed something inherently insecure.

oxguy3

Google Reader used Google accounts for authentication, so an exploit in Reader could potentially be compromising to your entire Google account. This very article gives an example of that; Looker Studio was used to reveal the name on any account, even though most accounts have likely never used Looker Studio.

Google could mitigate this by not having universally shared accounts across all services, but they're not going to do that because most users would find that inconvenient.

DSMan195276

> You designed something inherently insecure.

That describes most/all software older than a decade with no updates applied. How many libraries was Google Reader using that now have known vulns? I'm guessing it's more than zero.

This is the same logic as "just don't write bugs", if it was that easy everybody would already be doing it.

delroth

Google Reader was the last major user of the old social sharing stack at Google designed for Buzz, a product mostly remembered to these days for United States v. Google and the 2011 FTC consent decree. When people redesigned Google's social stack for G+ (e.g. all the infrastructure like Zanzibar underlying Circles, which to this day is close to state of the art!) the choice was between migrating Reader to the new tech - which nobody could justify the cost of - or keeping the old tech around for Reader when that tech was known to have had serious privacy issues leading to a major lawsuit.

paxys

If “what security implications does xyz have” was easy to answer then there would never be another hack or data breach. The simple answer is that we don’t know. And it is very expensive to find out.

olalonde

Brilliant. Just write secure code. I wonder why no one thought of that before...

fer

> It must be a daunting chore to maintain all the legacy pages

I always wonder who's the one maintaining the "poke" feature in Facebook.

bix6

I thought it was gone but I’m reading it was just hidden but re-added to the UI in 2024. That was always my favorite feature haha.

ctkhn

There are major things at some large enterprises that are given the same level of support. Friend works on an internal link shortener app that is heavily used at their mega corporation and it gets maybe one ticket every other sprint just for upgrading node versions etc even though its monitoring is down.

xnx

> Eventually you will land on a popup that uses the original Gmail look and feel, from 2004.

Indeed, I recently ran into a Google page that served up the old (~2013) Catull logo.

oxguy3

I was recently editing the Wikipedia page for Google Bookmarks (2005-2021). I wanted to add a logo to the page, but I was having a lot of trouble finding a high-quality copy of the logo anywhere. Eventually I figured out that Google's old URL scheme for product logos was very guessable, and they had never taken it down: https://www.google.com/intl/en-US/images/logos/bookmarks_log...

They'll probably never stop serving those old URLs because who KNOWS where they might still be in use. One of surely a million examples of weird little legacy things Google is stuck with.

xnx

That's good! Cool URLs never die. I thought they would be able to do a more effective search of their codebase to find references to their old logo in their own code.

jeffbee

I tried to guess what it might be ... I went to check moon.google.com, one of the older apps/jokes that I can recall still running. It seems that they got someone to update moon.google.com with a more recent look and feel, and dozens of moons instead of just the one.

And people say Google abandons products.

xnx

I'll share the url somewhere if I come across it again.

belter

> It must be a daunting chore to maintain all the legacy pages.

Clearly $350 billion revenue in 2024 is not enough...

Magmalgebra

Something that can be hard to appreciate if you haven't managed this sort of project is that it can be surprisingly hard to throw money at the problem.

If you try to hire at your regular "bar" for skill for boring work like this - people will often quit. This is one of the reasons many company's integrations are lacking despite it being a strategic interest - integration work is miserable and doesn't help your career.

Hiring below the skillbar at the same pay, is dangerous and often doesn't actually work out - if it was that easy someone more skilled probably would have fixed this a while ago.

So you try to pay more for the miserable work - but hold on, now you have to pay out of band salaries, and legal tells you that opens you to massive liabilities.

Ok - maybe you can just level them differently? No, HR will tell you that will mess with all your internal level processes - which are key to running the company. They're going to add a lot of additional overhead tracking these "fake" leveling bands and dealing with the consequences.

None of this means the problem is literally unsolvable, but it now requires a huge amount of time and effort from people near the top of the company who everyone would much rather spend their time on making the company better.

All of this to say - sure you could solve this problem, but it's actually much more complex than adding some line items to a budget.

Source: have watched many big companies try and fail for years to staff unsexy work like this.

AndrewDucker

You can give people time to go fix things that bug them. Two systems that you use don't work together and it bothers you? Have a day a week to fix it.

xp84

> pay out of band salaries, and legal tells you that opens you to massive liabilities

can you elaborate on this?

tough

isnt exactly this why most of it ends up outsorced to consultants or third parties generally?

staticshock

In addition to having the money, Google also needs the incentive to spend that money on such projects. If the perceived return on capital is low (or negative!), the incentive is simply not there.

reaperducer

In addition to having the money, Google also needs the incentive to spend that money on such projects. If the perceived return on capital is low (or negative!), the incentive is simply not there.

Perhaps Google should Google the concepts of "customer service," "standing behind your product," and "brand reputation."

0xbadcafebee

Google's main search page is the slowest page & UI I have found on the internet today (not accounting for bandwidth limits). Even on modern devices it lags at text entry and even rearranges characters in the text box so you have to wait 10+ seconds for it to finish loading or it will go haywire. The shopping and other pages are actually worse. So it appears you're right, $350B isn't enough money to maintain a web page in 2025.

jeffbee

There is something wrong with your computer.

xp84

don't forget how long the google.com redirect takes now if you dare to click a link on the SERP instead of just consuming their "AI Slop Overview" directly.

reaperducer

It must be a daunting chore to maintain all the legacy pages. The amount of now-years-old stuff that long-standing sites have to maintain, or choose to maintain, is shockingly high, and testing the combination of all that stuff is impossible.

One company I worked for used interns and new hires for that. One of the early tasks assigned to the intern pool was to comb the web sites for outdated information, or things that no longer conformed to the current brand book. The list then went somewhere else so the pages could be updated or deleted.

The major benefit of this was giving the new people an overview of what we do, why we do it, and a slice of the history of the products.

bornfreddy

On the other hand they had no idea if the information was valid or wildly outdated. But better something than nothing I guess. :-)

dylan604

This is where modern "learning" falls down. You load a page, read its contents, compare with what it is supposed to be, update if outdated, move on. I know I know, that sounds like, egad, work, but that's called a job.

Your immediate dismissal of an actual task I've been assigned irks to the point of being given a snarky response.

Brybry

> This time can also be significantly reduced through phone number hints from password reset flows in other services such as PayPal, which provide several more digits (ex. +14•••••1779)

I've never thought about this but it's extra scary. If you have the same phone number and email address with enough services and they all mask in a different order for reset hints...

paxys

If it makes you feel better (it probably won't) hundreds/thousands of services have collected your phone number over the years (for 2FA or any other reason), with or without consent, and a large chunk of them have had data breaches. So your name-email-phone number combo is 100% already available in public data dumps.

permo-w

not so long ago practically everyone's name and phone number was available publicly for free in any phone box

Rychard

Not to mention that these "phone books" also included everyone's address, and married couples were usually listed together.

dylan604

people always trot this out, but it was very possible to have your information unlisted so it was not printed in the book. you could also use a different name. an old coworker selected to have his name listed as David King so that when found in the book it would show up as King David.

having an unlisted number wasn't uncommon. for privacy minded people, it was a simple phone call to make it unlisted, and most just did it at time of getting the number.

wat10000

You could pretty easily opt out of that, at least in many places, although you might need to pay a small fee.

nicce

If you have used Twitter or Facebook long enough while keeping the account, public your information is.

paxys

Or Yahoo, AT&T, T-Mobile, Equifax, Capital One, Chase, eBay, Home Depot, Marriott, most health networks...

westmeal

Thanks yoda

rvnx

There are now Telegram bots to find such information. The fact that this bruteforce was revealed probably annoyed many users (like the infamous "EoG" bot).

0x_rs

There's services that do this automatically for a price, and they've been around for a while, for e-mail, phone numbers, and much more. Any bits (literally, bits) of information given without authorization (or plausible belief it's the intended user on the other side) will be efficiently put together from a variety of sources, as there's no shortage of incentive, and many all over the world prodding services used by billions of people worldwide. And then eventually leaked..

ghaff

There used to be deep web services that provided a lot of this stuff for free back in the early 2000s or so. I think everything like that is behind at least some level of paywall now but it's not hard to get a fairly complete dossier on someone given a bit of background information and a pretty small expenditure.

lesuorac

There were a few stories in the past about people social engineering their way past support by asking one companies support for the last 4 of a card and then using that last 4 for a different company.

anonymars

Here's the one I'm thinking of (time flies, doesn't it?)

https://www.wired.com/2012/08/apple-amazon-mat-honan-hacking...

> Those security lapses are my fault, and I deeply, deeply regret them.

> But what happened to me exposes vital security flaws in several customer service systems, most notably Apple's and Amazon’s. Apple tech support gave the hackers access to my iCloud account. Amazon tech support gave them the ability to see a piece of information – a partial credit card number – that Apple used to release information. In short, the very four digits that Amazon considers unimportant enough to display in the clear on the web are precisely the same ones that Apple considers secure enough to perform identity verification. The disconnect exposes flaws in data management policies endemic to the entire technology industry, and points to a looming nightmare as we enter the era of cloud computing and connected devices.

946789987649

When I was at university, I went to a talk from a security researcher who found this was the case with credit cards.

c22

Even scarier, whoever has access to admin those services can just look up the unmasked data! Better to use unique numbers and addresses per service.

dkdcio

what’s the risk? your email being made public? your phone number?

rvnx

Get personal info, then call carrier for a SIM swap, access crypto from there. Bonus: no KYC, since it's the other person's identity + you can login from 4G internet, so a trusted IP range.

qingcharles

Where can I get this though?

I haven't been able to get into my main Google account for years because they enabled 2FA without warning and it had a phone number I no longer have. I have the username and password and I get all the emails because I also have the recovery email address. I just need to get the recovery code by SMS.

shruggedatlas

What can be done to protect oneself from a SIM swap attack?

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AtomicByte

This is super creative and cool. Brutecat back at it again heh

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PeeMcGee

Wow, if I needed any more proof Google is a ghost ship then this is it. The $5K bounty is an insult, and the fact that they low-balled it in the first place makes them look like absolute clowns. Good on you for calling out how little of a shit Google gives about actually protecting user data.

jcims

Nobody is forced to participate in a bug bounty. If you don't like the rewards, don't do it. There's a limit to the financial viability of these programs.

sjg1729

If the bug bounty program doesn’t pay out much, there will be plenty of less reputable actors happy to pay more

dns_snek

Who's talking about participation? We can be appalled by their business practices as their customers (actual or potential). These are the same companies that tell us that our privacy and security is their #1 concern, and use that justification to take away our rights "for our own good", but when there's a real threat they address it with with a business-casual equivalent of "fuck off".

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paxys

Neat find, though it's funny to me that a phone number is something people (including everyone on this thread I bet) have been handing out like candy their entire adult lives - to friends, stores, banks, employers, government agencies, random websites – but still expect it to remain some critical secret that no one should ever find out. A phone number is about as private as your name, and you should consider it as such.

beezlewax

No it isn't. You give it to people you trust mostly you don't expect them to make it available publicly on the Internet.

paxys

You really trust that not a single friend of yours has ever clicked the "share contacts" button after downloading Facebook/Instagram/Snapchat/LinkedIn/TikTok...? You trust that your auto dealer or bank has not shared your details with Experian (even though you signed a piece of paper explicitly authorizing that)? You trust that your mobile operator itself isn't sharing your contact data with advertisers (go back and read your carrier agreement)? You trust that your grocery store's membership system has fool-proof IT security? Look up "recent data breaches" on Google and see how many of those companies/hospitals/government agencies you had a relationship with. I can guarantee that despite your best efforts and "trust" your phone number is accessible in a few clicks to anyone who cares to look.

xp84

I feel like both sides are right here:

1. Google shouldn't make it trivial to find out my phone number from my email. Given that even Google itself, despite having better technology available, still allows the dumpster that is SMS verification to be used as an auth "factor," they should not be enabling SIM-swapping so directly. Just knowing someone's number makes it trivial to social engineer a SIM-swap, and that can likely unlock every account most people have, and a lot of important accounts (like banks) even for security-minded people, since banks love SMS and hate everything else.

2. I shouldn't act like my phone number is a well-protected secret, or trust that anyone who calls or texts me has gotten it from a trusted source.

kccqzy

> A phone number is about as private as your name

Your name should also be somewhat private. No need to use your real name on the internet. There was a furor over Google requiring real names on Google+; this kind of outcry needs to continue.

prophesi

This is why I use things like Firefox Relay's email/phone masking for sites and services I don't trust. Would be interested if people know of free alternatives, as the phone mask requires their premium plan, and that can be a no-go for friends and family.

paxys

It helps somewhat, but unless you give a unique number to every single friend, business, bank, store, your real number will find its way into data breaches sooner or later. Heck AT&T and T-Mobile have themselves had large scale hacks in the last few years.

psunavy03

Uhh . . . this is not an earth-shattering take, considering they used to publish entire books with everyone's phone numbers and addresses in them, and you had to pay a fee not to have your number listed.

Are we really to the point people don't understand the concept of a phone book anymore?

jeroenhd

Back when phone books were a thing, you couldn't take over a phone number from the other side of the country in the middle of the night and use it to transfer funds to a foreign bank account before you even wake up.

Social security numbers were also never supposed to be secret but as their use changed over the years, so did the way people treat them.

Yes, phone numbers are leaked everywhere. So are social security numbers and home addresses. That doesn't mean your website should be leaking that information.

sumtechguy

Do I give it out? Not so much.

Do I expect it to be private? No.

You can for a small fee on some websites get my number.

Heck if you find a phone book from ~2000 where I use to live then you could just look it up in the phone book. Number portability saw to that.

Considering the number of data breaches and past history of phone numbers. To expect any sort of privacy is 'nice to have' but not going to happen. At this point it is basically security thru obscurity to expect it to be private.

Even when they had 'unlisted' numbers you could buy a book from the phone company that had it in there anyway. They even had reverse phone books you could buy. I even remember CD's from ~1998 that had the whole country. You didn't even need to keep the books.

bornfreddy

Things have changed in the last decades. With all the unsolicited calls (and especially scams) one would prefer to keep their phone number as private as possible. Doesn't mean that delivery can't get it, just that it shouldn't be on the net.

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msdrigg

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jsnell

Logging in at all requires JS, so there's very little value to a no-JS username recovery flow.

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miyuru

TIL about another google product I knew nothing about. https://lookerstudio.google.com

paxys

Not a homegrown product. Looker was a pretty popular tool for data analysis and visualization and was acquired by Google a while ago.

datadrivenangel

Lookerstudio was formerly google data studio, which was homegrown at google!

whalesalad

You are blessed to have not been harassed by your GCP rep to attend a demo of this software.

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