4 ms·

I'm gonna go out on a limb and suggest that this obfuscation scheme is legacy, and they keep it merely as defense in depth and because it's tested so why not.

I'm gonna go out on a limb and suggest that this obfuscation scheme is legacy, and they keep it merely as defense in depth and because it's tested so why not. Modern Macs can do remote attestations from a trusted boot chain all the way up to specific apps, which obviates the need for this sort of obfuscation. The memory spaces will be protected by the operating system as long as SIP is enabled, and if it's not enabled or has been disabled / the root partition has been modified, then that will be detectable by Apple remotely. Although code obfuscation is fun (I've built a virtualization based obfuscation in the past), a properly implemented remote attestation and security architecture does obsolete it. It's therefore mostly useful on Windows/Linux PCs where these schemes don't really hang together.

nicolodev 3y ago
Thanks for your comment. This obfuscation scheme is used only to complicate any attempt to reverse engineering (disassembling, decompilation) of the two processes involved in FairPlay DRM (I'm mainly talking about CoreFP and Fairplayd). Attackers need to spend more time on retrieving the original business logic. For sure, it's not the most hyper-defense technology Apple has employed (think about Secure Enclave). > a properly implemented remote attestation and security architecture does obsolete it [obfuscation] I'm not sure I've understood this part. So, if Apple implements remote attestation, would it be more difficult for attackers to reverse engineering the application? I am probably missing a point, would you mind if I ask you to expand that?
- baby_souffle 3y ago
  > I'm not sure I've understood this part. So, if Apple implements remote attestation, would it be more difficult for attackers to reverse engineering the application? I am probably missing a point, would you mind if I ask you to expand that? It's not to prevent RE. Apple can detect tamper so it's no concern if you RE it or not. Anything you learn from that RE work will almost certainly mean tampering with the system...
- mike_hearn 3y ago
  RA tells Apple what software stack you're running and that it's not virtualized (genuine hardware device). Therefore, you no longer need software obfuscation because: 1. The software is now tamperproofed (server won't release content key unless the RA contains an expected hash) 2. The memory space is protected from being read from other processes, so there's no need to try and hide the processing of secrets in the code itself. i.e. a system based on RA can be entirely transparent, open source even, and it can still work. The only secrets are the hardware keys that act as the root of trust. The software and hardware stack does itself need to be secure of course, but Apple has got pretty good at that. And btw Apple's platforms already support remote attestation: https://developer.apple.com/documentation/devicecheck https://developer.apple.com/documentation/devicecheck
  - nicolodev 3y ago
    Thanks for the detailed explanation. > The software and hardware stack does itself need to be secure of course Oh this is what I'm missing. It's a huge assumption that I wish that can be true!
    - mike_hearn 3y ago
      Is it not true? Not everything needs to be secure, just the right parts. The test is whether you can jailbreak the devices and not be detected by their RA scheme. As far as I know, there's no (public) way to do this. BTW, this tech isn't new. In practice if you are vertically integrating, it's possible to make things secure enough. Games consoles have been doing this for years. Even in the Xbox 360 era, the use of local exploits was detectable the moment you connected to Xbox Live, and AFAIK Xbox One remains completely unmoddable/unjailbroken even after a decade into its lifespan. There's a tech talk here by a member of the Xbox team who talk about how they secured it against physical attack: https://www.youtube.com/watch?v=U7VwtOrwceo https://www.youtube.com/watch?v=U7VwtOrwceo But bear in mind, RA was never the weak point even of the 360. Making remote attestation secure is a well studied problem in the industry. It's been done several times. You have to be a competent tech firm producing your own hardware/software combos, and you need a competent security team, but there are several companies that meet that criteria and Apple is definitely one of them.
twoodfin 3y ago
It’s also likely strong evidence in court that you can’t acquire a copy of protected content without activity that is clearly circumvention.
deleted 3y ago
[deleted]
mistrial9 3y ago
Dear Sir - a "a properly implemented remote attestation and security architecture" is one aspect of computing, but ironically, Apple Computer built its empire on "personal computers" not military style ID checking. constant "papers, please" to run My Own Computer is not what I purchased hardware to do.. signed -US Citizen

nicolodev 3y ago

Thanks for your comment. This obfuscation scheme is used only to complicate any attempt to reverse engineering (disassembling, decompilation) of the two processes involved in FairPlay DRM (I'm mainly talking about CoreFP and Fairplayd). Attackers need to spend more time on retrieving the original business logic. For sure, it's not the most hyper-defense technology Apple has employed (think about Secure Enclave). > a properly implemented remote attestation and security architecture does obsolete it [obfuscation] I'm not sure I've understood this part. So, if Apple implements remote attestation, would it be more difficult for attackers to reverse engineering the application? I am probably missing a point, would you mind if I ask you to expand that?

baby_souffle 3y ago
> I'm not sure I've understood this part. So, if Apple implements remote attestation, would it be more difficult for attackers to reverse engineering the application? I am probably missing a point, would you mind if I ask you to expand that? It's not to prevent RE. Apple can detect tamper so it's no concern if you RE it or not. Anything you learn from that RE work will almost certainly mean tampering with the system...
mike_hearn 3y ago
RA tells Apple what software stack you're running and that it's not virtualized (genuine hardware device). Therefore, you no longer need software obfuscation because: 1. The software is now tamperproofed (server won't release content key unless the RA contains an expected hash) 2. The memory space is protected from being read from other processes, so there's no need to try and hide the processing of secrets in the code itself. i.e. a system based on RA can be entirely transparent, open source even, and it can still work. The only secrets are the hardware keys that act as the root of trust. The software and hardware stack does itself need to be secure of course, but Apple has got pretty good at that. And btw Apple's platforms already support remote attestation: https://developer.apple.com/documentation/devicecheck https://developer.apple.com/documentation/devicecheck
- nicolodev 3y ago
  Thanks for the detailed explanation. > The software and hardware stack does itself need to be secure of course Oh this is what I'm missing. It's a huge assumption that I wish that can be true!
  - mike_hearn 3y ago
    Is it not true? Not everything needs to be secure, just the right parts. The test is whether you can jailbreak the devices and not be detected by their RA scheme. As far as I know, there's no (public) way to do this. BTW, this tech isn't new. In practice if you are vertically integrating, it's possible to make things secure enough. Games consoles have been doing this for years. Even in the Xbox 360 era, the use of local exploits was detectable the moment you connected to Xbox Live, and AFAIK Xbox One remains completely unmoddable/unjailbroken even after a decade into its lifespan. There's a tech talk here by a member of the Xbox team who talk about how they secured it against physical attack: https://www.youtube.com/watch?v=U7VwtOrwceo https://www.youtube.com/watch?v=U7VwtOrwceo But bear in mind, RA was never the weak point even of the 360. Making remote attestation secure is a well studied problem in the industry. It's been done several times. You have to be a competent tech firm producing your own hardware/software combos, and you need a competent security team, but there are several companies that meet that criteria and Apple is definitely one of them.

twoodfin 3y ago

It’s also likely strong evidence in court that you can’t acquire a copy of protected content without activity that is clearly circumvention.

deleted 3y ago

[deleted]

mistrial9 3y ago

Dear Sir - a "a properly implemented remote attestation and security architecture" is one aspect of computing, but ironically, Apple Computer built its empire on "personal computers" not military style ID checking. constant "papers, please" to run My Own Computer is not what I purchased hardware to do.. signed -US Citizen