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Comment by robjan | Hacker News Reader

The issue isn't Amadeus, it's that some airlines don't bother to use accounts with lower levels of privileges for operations which don't need full access. There are a number of different levels which are intended to be used for different purposes: for example, the credit card numbers are not visible to booking agents but can be accessed by the anti fraud department.

Some airlines just use a single "god mode" account for their whole e-commerce platform because it's cheaper / more convenient for their developers / vendors.

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Could you explain how returning all data to the frontend is connected with "god mode" usage? Is the Amadeus system such that it created/masks different fields in the data depending on the access level you have?

In this case, "hacker" logged in a customer facing portal, this is probably not even an user account in the strict sense of the word.

I am asking as I fail to see how it is not a development issue. If they returned only the data that was needed on the page, it wouldn't expose internal comments or passport IDs.

There are of course two errors that the developer of the backend made. The first is not filtering what came back from the Amadeus API, but the second one - the one I am referring to - is using an Amadeus API key with too much access.

Amadeus filters the booking record depending on the level of access that the user accessing it has (the user being the backend in this case). In a previous life for another airline, I have experienced this problem before when a vendor tried to get something through to production which was retuning credit card numbers and expiry dates to the frontend (but not the CV3). This was all because the vendor tried to use the highest privilege API key rather than the one with access to the specific info they needed. It never got past UAT thanks to thorough security review in this case.

The API key shouldn't change what type of data an API call returns. The developer should explicitly request data and that either succeeds or fails based on authorisation. Making assumptions about the use case from the key will of course lead to this kind of error.

The PNR (passenger name record) is the data record which represents your booking on Amadeus. It's basically a semi-structured flat text file. Each line is an entry which may represent a leg of your journey, your name, the payment method used to make the booking or various remarks (which themselves are arbitrarily structured).

These lines are filtered / redacted depending on your role. You have to remember that this is a legacy system which has remained pretty much unchanged for 40-50 years. It's hard to change because hundreds of airlines have their own legacy systems which rely on bookings being structured this way. And when you book a multi-carrier itinerary, the airlines often all access this same record directly on Amadeus.

There has been some movement in recent years in a platform called NDC[0] (new distribution capability) but most airlines still rely on the PNR at the moment.

[0]: https://www.iata.org/en/programs/airline-distribution/ndc/

This is pretty standard when fetching entire complex objects from many backends. You get the full object with all of the fields the authorization layer allows you to see.

Something like "GET /reservation/<id>" would rarely require you to specified the 50 fields that you would like included in the response. Many offer fields to explicitly filter for specific things, but the default is almost always to return the full object as much as the caller is allowed to see.

You shouldn’t arbitrarily include or exclude information. The response to a given input should always be the same output, and not depend on what API key you are calling with.

I agree. Using API key to determine what kind of information is returned is a strange solution. It would effectively mean that if the airline is developing an application that has multiple levels of users (airline employees, customers, admins) it would need to store and use multiple API keys to retrieve the data.

Ofcourse, real solution here is that the airline software should not just pass along everything it received from Amadeus but rather that they should convert it and return only the relevant subset. This would avoid these type of issues.

Well unfortunately that's just not how the real world works. In most production systems you are going to end up with a bunch of fields that aren't visible to regular users. There ends up being a whole bunch of roles that need access to different levels and instead of implementing separate APIs for every user type, you just mask out the fields a specific type isn't allowed to see.

This is frequently called property level authorization or field level authorization.

https://stackoverflow.com/questions/30002351/enforcing-prope...

https://help.salesforce.com/articleView?id=security_data_acc...

You're just wording it in an indirect way to make it seem like something different. It's not "Using API key to determine what kind of information is returned", it's "hiding sensitive fields based on permissions".

It's not arbitrary. It's based on authorization levels for object properties/fields. If you haven't encountered this it's likely that you haven't spent much time working on a system with many different distinct classes of actors.

Developing a different getUser API for 20 different caller types does not scale.

OK, thank you for the explanation. I was not aware that Amadeus is some type of backend system that airline software integrates with.

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