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Apple: Developer ID Certificate Revocation (OCSP)

lapcatsoftware.com

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Re: Apple: Developer ID Certificate Revocation (OCSP)

#11

Post by jchw »

abiogenesis wrote: post #8
jchw wrote: post #4

Earlier quoted context omitted.

Your quote of Lapcatsoftware is just wrong. It is not: > Apple is to blame for revoking this certificate. It is: > So blame must be apportioned to both companies. ...because the revocation itself seems to have been an unjustified request. It seems the value-add of Apple having the sole ability to revoke certificates would be that they could avoid something like this. (That said, I do think this is still mostly HP's f…

What should be the proper process then? Should Apple reply to all revocation requests asking for a proof that the certificate has really been compromised? OCSP or CRL revocations are easy to revert, so why risk letting a compromised certificate to be used for an extended amount of time?

Beats me. Apple could just give developers full discretion, which would lower the amount of time it takes to get a really compromised certificate even more. Presumably, there is some good reason to have manual discretion, otherwise, why have it?

Re: Apple: Developer ID Certificate Revocation (OCSP)

#12

Post by saagarjha »

X-Istence wrote: post #7
saagarjha wrote: post #6

Earlier quoted context omitted.

Apple's revocation policy gives you no control over the revocation–you ask them to revoke things for you by contacting them, and then they decide whether this seems like a valid request, then they grant it for you. This is not how revocation usually works, so if so, why is Apple not vetting requests when they are placing themselves into the process?

That's the same way a CA works (except with a bit of automation instead of emailing someone). I go to the CA that issued my cert and say "I'd like to revoke this" (whether that is an API call or an email), they then publish the cert into their certificate revocation list. Now, Apple could deny a request, but they are under no obligation to do so, and I would argue that they shouldn't be making those judgement calls.…

But that is exactly what they claim they are there to do. They should either just accept any request, or do a good job at denying incorrect revocations.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#13

Post by X-Istence »

saagarjha wrote: post #12
X-Istence wrote: post #7

Earlier quoted context omitted.

That's the same way a CA works (except with a bit of automation instead of emailing someone). I go to the CA that issued my cert and say "I'd like to revoke this" (whether that is an API call or an email), they then publish the cert into their certificate revocation list. Now, Apple could deny a request, but they are under no obligation to do so, and I would argue that they shouldn't be making those judgement calls.…

But that is exactly what they claim they are there to do. They should either just accept any request, or do a good job at denying incorrect revocations.

Where do they claim to do that? Maybe there is no API for it because it happens so rarely that letting the Apple Security team push a few buttons is more cost effective.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#14

Post by bentcorner »

abiogenesis wrote: post #8
jchw wrote: post #4

Earlier quoted context omitted.

Your quote of Lapcatsoftware is just wrong. It is not: > Apple is to blame for revoking this certificate. It is: > So blame must be apportioned to both companies. ...because the revocation itself seems to have been an unjustified request. It seems the value-add of Apple having the sole ability to revoke certificates would be that they could avoid something like this. (That said, I do think this is still mostly HP's f…

What should be the proper process then? Should Apple reply to all revocation requests asking for a proof that the certificate has really been compromised? OCSP or CRL revocations are easy to revert, so why risk letting a compromised certificate to be used for an extended amount of time?

I agree that HP was careless here but IMO Apple should learn here that developers who ask for a cert revocation may not understand the consequences or the cases where this is necessary.

I have no idea what the cert revocation workflow looks like, but providing cases where it should and shouldn't be used would be useful.

It's still certainly possible that this falls squarely on HP and there's only so much you can do when someone is determined to blow their foot off.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#15

Post by _qulr »

X-Istence wrote: post #9
jchw wrote: post #4

Earlier quoted context omitted.

Your quote of Lapcatsoftware is just wrong. It is not: > Apple is to blame for revoking this certificate. It is: > So blame must be apportioned to both companies. ...because the revocation itself seems to have been an unjustified request. It seems the value-add of Apple having the sole ability to revoke certificates would be that they could avoid something like this. (That said, I do think this is still mostly HP's f…

Replace Apple with any CA on the world wide web, if I go ask them to revoke a certificate, they should just do as I ask. Not try and second guess me. Apple is not to blame for HP requesting the certificate be revoked, not even apportioned. HP is the sole requestor and the sole entity responsible for the cert being revoked.

> Replace Apple with any CA on the world wide web

This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different.

Apps installed on a user's Mac are expected to run indefinitely, essentially forever. Developer ID signing certs do expire, but expiration only affects their ability to sign new app versions, it doesn't prevent old versions signed with the cert from running. The expired cert is still considered valid when you launch the app on a Mac.

When you connect to foo.com on the web, the server can use any valid cert. Certs get replaced quite frequently, often yearly. If you put a new cert on the server and revoke the old one, it doesn't necessarily harm web users, because they can make new connections with the new cert. But if a Developer ID cert is revoked, then macOS immediately (on OCSP check) prevents any app ever signed with that cert from launching, and calls it "malware". (The main purpose of Developer ID is to stop the spread of malware.) Even if the app has been installed on the user's machine for a long time, the app will no longer run. Revoking a Developer ID cert is a remote kill switch for Mac apps. This is why revocation of Developer ID certs is so destructive, and is almost always reserved only for malware.

The analogy with web CAs simply does not hold here.

Until this HP case, I've never heard of a 3rd party developer requesting that a Developer ID cert be revoked. All cases I've heard of are when Apple revokes the cert of a malware writer, which obviously the malware writer did not request.

A remote kill switch for Mac apps is extremely destructive, which is why only Apple has the power to revoke the Developer ID certs, which they should only do for a very good reason, such as malware.

It's also important to note that Developer ID is a requirement that Apple imposed on third party developers, purportedly for security purposes. We developers never wanted this, but we had no choice. Again, none of this is really under our control, it's Apple's program, and Apple is the sole CA for Mac app certs.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#16

Post by meibo » 

  The check consists of an HTTP GET request (port 80, unencrypted!) to ocsp.apple.com
Am I missing something? Is this still the case?

Seems like an obvious privacy issue, to be able to identify if an user is launching apps from a certain developer just by doing very basic packet capture.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#17

Post by donor20 »

What the heck. You don't have to prove private key compromise for a CA to revoke a cert, you just ask them to revoke it. How in the world is this apple's fault?

As long as they authenticate the person requesting the revocation. In most CA's, this can be done by signing the request with the private key to prove control.

Now we are told that blame "MUST" be apportioned? "HP and Apple failed in their responsibility"

For all we know HP could have found a remote zero day exploit in their drivers, and was going to initiate a replacement effort or something.

The author also complains no CRL is available, but that's a good thing in these cases, if there is a mistake certificate status can be updated. So again, apple has an approach here that means it's not too hard to get folks printing again.

The author makes a case that a publisher can only revoke in the case of malware and key compromise. I can think of PLENTY of situations where revocation might make sense (and publisher may be still sued I'm sure) outside of that, for small teams and even for big teams.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#18

Post by goalieca »

_qulr wrote: post #15
X-Istence wrote: post #9

Earlier quoted context omitted.

Replace Apple with any CA on the world wide web, if I go ask them to revoke a certificate, they should just do as I ask. Not try and second guess me. Apple is not to blame for HP requesting the certificate be revoked, not even apportioned. HP is the sole requestor and the sole entity responsible for the cert being revoked.

> Replace Apple with any CA on the world wide web This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different. Apps installed on a user's Mac are expected to run indefinitely, essentially forever. Developer ID signing certs do expire, but expiration only affects their ability to sign new app versions, it doesn't prevent old…

> Replace Apple with any CA on the world wide web This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different.

The brilliant thing about pki is that certificate usage is based on its cryptographic purpose. It doesn’t care about the application itself.

It’s actually a good thing that Apple doesn’t just verify the certs on install. The kill switch serves a vital security purpose.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#19

Post by ytch »

_qulr wrote: post #15
X-Istence wrote: post #9

Earlier quoted context omitted.

Replace Apple with any CA on the world wide web, if I go ask them to revoke a certificate, they should just do as I ask. Not try and second guess me. Apple is not to blame for HP requesting the certificate be revoked, not even apportioned. HP is the sole requestor and the sole entity responsible for the cert being revoked.

> Replace Apple with any CA on the world wide web This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different. Apps installed on a user's Mac are expected to run indefinitely, essentially forever. Developer ID signing certs do expire, but expiration only affects their ability to sign new app versions, it doesn't prevent old…

> Apps installed on a user's Mac are expected to run indefinitely,

But if a malware is signed and installed to a computer, revoke it can prevent further running.

Re: Apple: Developer ID Certificate Revocation (OCSP)

#20

Post by fatratchet »

_qulr wrote: post #15
X-Istence wrote: post #9

Earlier quoted context omitted.

Replace Apple with any CA on the world wide web, if I go ask them to revoke a certificate, they should just do as I ask. Not try and second guess me. Apple is not to blame for HP requesting the certificate be revoked, not even apportioned. HP is the sole requestor and the sole entity responsible for the cert being revoked.

> Replace Apple with any CA on the world wide web This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different. Apps installed on a user's Mac are expected to run indefinitely, essentially forever. Developer ID signing certs do expire, but expiration only affects their ability to sign new app versions, it doesn't prevent old…

>This is what everyone misunderstands. The Developer ID code signing program is not analogous to web certs. The usage of these certs is entirely different.

If a web cert gets revoked a browser won't accept it when making a connection to a domain/server anymore even if they previously did (unless you make it). If an app signing cert gets revoked the OS won't run a binary signed with it anymore even if it previously did (unless you make it). Sounds similar enough to me, minus expiry handling.

Revocation is indeed extremely destructive and should only used by Apple on their own accord against malware but I don't see why a dev themselves shouldn't be able to revoke their own cert without having to go back and forth with the Apple security/support team to have to try to convince them that the issue is severe enough.

The main and basically almost only reason where I see developer side revocation be used is if their keys or account have been (possibly) compromised and therefore there's a chance of it being used for malware. Time can be of big importance in a situation like that too. As a user I absolutely want Apple to revoke certs when requested by the dev themselves without triple verifying if they are really totally actually absolutely sure. I consider the upsides of that to outway the downsides.

While a binary from a dev that has been installed for a long time will be less likely to be malware but not enough to be exempt from that.

Users that dislike OSCP can disable it fully on their side if they want or locally sign anything specific they do trust. Devs didn't ask for it but having developer IDs and application singing seems like a pretty sensible thing to me in an end user OS used by the average consumer.

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