'123456' password exposed chats for 64M McDonald's job applicants
44 comments
·July 11, 2025bsuvc
hardwaresofton
A third problem that senior engineers might recognize: using numeric IDs on an outward facing object. UUIDs would have made this impossible as well
jszymborski
Ok, this is probably a stupid, very bad, no good idea considering I've not heard of people doing this, but can't you retain many of the benefits of numerical IDs but also the secrecy of UUIDs by using an HMAC ?
With HMAC, you can still ask for some sequential IDs
SipHash128(0, KEY) = k_0
SipHash128(1, KEY) = k_1
You get the same number of bits as a UUID.
You can't, however, sort by IDs to get their insertion sequence, however. For that you'd need something like symmetric encryption but this is already a bad idea, no reason to make it worse.
hardwaresofton
You could also "just" have an internal-use only numeric ID, or use a UUIDv7.
lelandbatey
Using numeric IDs on an outward facing object is, for the most part, totally fine. It's a serious tradeoff to ditch the nice properties of numerical IDs and the legibility they provide in order to cargo-cult a "we must reveal nothing" approach, as you would here via UUID. It also misses the point of the actual security lesson: no matter the identifier, you need to be applying access controls to your data. Even if your UUIDs were generated via 100% airtight cryptographically random sources, you have to, y'know, communicate with them. That means you'll probably leak them, expose them, or other folks will collect them (often incidentally via things like system logs). If all it takes to gain access to a thing is knowing the identifier of that thing, you've blown it in a huge way. Don't stress about the theoretical benefits of something like an opaque identifier and then completely neglect the necessary real world access control.
Can you tell I've been scarred by discussing designs with folks who focus on the "visible" problems without thinking about the fundamental question of "is this secure"?
hardwaresofton
I think I disagree with "totally fine"... Even if that were true though, this case is definitely a point where you wouldn't want to give away information with a numeric ID. Giving away # of applications/growth of that over time is definitely business information that arguably should not be discernible.
The point is not that UUIDs are magically secure, it's that they mean nothing to whoever gains access except a single job app. The assumption is that they will get out (they're in a public URL), and that they will have no meaning when they do.
It's a defense-in-depth thing IMO -- cargo-culting this approach defends you even when you don't do the other things right. It's simple -- with a non-zero probability that the actual access control is faulty, do you want a default that protects you or doesn't. What's the intentional trade we're going for? More DB perf? Easier to type URLs? There are other ways to deal with those
> Can you tell I've been scarred by discussing designs with folks who focus on the "visible" problems without thinking about the fundamental question of "is this secure"?
Yes :(
mattl
Yes it makes very little difference if I can see all your public published blog posts on a WordPress site by iterating the number.
bsuvc
Not impossible, just more difficult to guess.
"Security through obscurity" isn't really good enough.
tyre
Yes and…
UUIDs aren’t “just more difficult to guess.” They are inconceivably harder to guess.
> Put another way, one would need to generate 1 billion v4 UUIDs per second for 85 years to have a 50% chance of a single collision.
hardwaresofton
Yes, you are technically right -- I should have said "functionally impossible". It's not actually impossible, but close enough for the average random onlooker.
thaumasiotes
> It sounds like there were two separate problems:
> The first was that 123456 was the credentials for the admin panel.
No. 123456 was the credentials for the test setup, which contained nothing. But you could use the IDOR to access data from the test setup.
If 123456 had been the credentials to the admin panel, there would have been no point in exploiting an IDOR - as an admin, you can just look at whatever you want.
Natsu
123456 was both the username & password, they were hit by CWE-1392 because someone failed to change the default credentials.
thaumasiotes
The writeup never claimed that 123456:123456 were default credentials?
gnabgib
Discussion (125 points, 2 days ago, 69 comments) https://news.ycombinator.com/item?id=44513940
micw
Wait, 64 million applicants, not applications? That's like 20% of the US population!
mousethatroared
Others have said it's for the global site, but would 64 million really be that off for the US?
I just looked it up 13 of the 40k francises are in the US. Assuming linearity, thats about 21 million US applicants since they started keeping centralized, digital records.
20% of Americans younger than 40 is not a bad guess.
crazygringo
Which is 1,615 applicants per US franchise.
Seems totally reasonable to me.
2 shifts of 12 employees is 24 employees per day. Assume they all work there for 6 months on average, then if the system's been up for 10 years, that's 480 employees per franchise over a decade. Which means for every employee they hired, 2 were either rejected or chose not to work there.
Working at McD's is something a lot of people do for a few months when they're young.
Volundr
Maybe it includes applications outside the US?
bigfatkitten
They use this site for hiring globally. The number of privacy regulators they will have to notify and deal with is going to make this messy.
atm3ga
If this was disclosed via a vulnerability disclosure or bug bounty program and there are no indicators of a data breach then it's effectively like the findings from a pen-test so very likely no regulatory reporting requirements.
deafpolygon
Incredible! That’s the combination to my matched luggage!
sans_souse
The spoof prophecies are being proven! now we're all stuck in a real-life Spaceballs movie.
bigmattystyles
Just in time for the sequel!
jonplackett
For the uninitiated (ie probably anyone under 35)
dylan604
Earlier this year, Mel posted a video saying they are making a sequel.
mattl
Check your luggage for fries
pyman
Please stop giving OpenAI ideas on where to find and download more data!
$ Downloading 64M transcripts...
ajsnigrutin
It's funny how mcdonalds did everything in their power to make it almost impossible to run their mcdonalds app on a rooted phone, but their backend infrastructure is beyond broken (security wise)
ceejayoz
The McDonalds consumer-facing app is quite possibly the worst app from a major company I've ever encountered. It's shockingly bad.
parpfish
The UI is atrocious.
I do computers for a living and can barely navigate and figure out what’s going on.
hippich
Btw, I wondered why they flight root on the phone at all?
le-mark
My theory is they store payment information on the mobile app. The app connects to the store wifi automatically, even when going through the drive thru. And processes the payment then. I theorized it so they don’t store credit card info on their servers, simplifying their PCI audits. Presumably they think all that is better than preventing the app from running on rooted phones.
ajsnigrutin
I have no idea... maybe they store their "coupons" locally and are afraid you'll clone them? Don't know, I eat there twice a year and it's not worth it :)
suhide in magisk makes my banking app work, but not mcdonalds :)
tonetheman
[dead]
theturtle
Wait, sixty-four MILLION people actually wanted to work there?
Are they counting everybody since 1954?
chungy
It's the second largest fast food chain, behind Subway. It is everywhere and provides steady good work.
There should be no surprise here.
notepad0x90
getting jobs is hard. majority us on this thread couldn't get a job at mcdonalds if we tried our best. and that's mostly because they think we'll quit after a few days/week. and there are harder to get jobs that pay even less! it's about supply/demand, not how desirable the job is.
It sounds like there were two separate problems:
The first was that 123456 was the credentials for the admin panel.
The second was an insecure direct object reference, where the lead_id querystring parameter can be changed on an API call to retrieve another applicant's data.