4 ms·

I'm happy to have this setting. It's a great setting and I appreciate Signal adding it. However, if an attacker has the ability to directly query the Recall da

I'm happy to have this setting. It's a great setting and I appreciate Signal adding it. However, if an attacker has the ability to directly query the Recall database, they almost certainly have access to read all your Signal messages on your device. The locations where Recall files live are even more protected and isolated than your %APPDATA%\Roaming\Signal directory is. Everything running as you on your computer has full control of all your Signal messages and your identity assigned to the device. This is untrue of your Recall data, which from last I saw required a lot of finagling to get the permissions right for you to access it raw.

advisedwang 1y ago
At least this gives forward secrecy, so if someone takes control of your computer they can only spy on signal messages AFTER that point, and can't access prior messages that Recall has captured.
- vel0city 1y ago
  This is only forward secrecy for messages that were deleted and would have been captured by Recall and are still within the snapshot history which has a maximum number of days. All the messages you've previously synced to the device exist in that Signal AppData directory and can be trivially searched and read by any application running as your user account. And all attachments are also just sitting there. For example: https://vmois.dev/query-signal-desktop-messages-sqlite/ https://vmois.dev/query-signal-desktop-messages-sqlite/
  - acdha 1y ago
    Given how popular the disappearing messages feature is, a lot of messages are going to be deleted where Recall is a second, less tested copy of things which the user believes are gone. Given the past history of AI tools it seems dangerously likely that someone would find that their Recall history was retained longer than necessary or could be retrieved through some creative misuse of Recall which doesn’t require system access.
    - vel0city 1y ago
      > Given how popular the disappearing messages feature is, I don't think it's really that popular or extensively used. Most people I know who use signal use it pretty rarely. I'll turn it on when I'm about to send something sensitive, but generally it's not enabled. I've been using Signal since 2015 and I've probably only sent or received a hundred or so disappearing messages. I've sent and received many, many thousands of messages. And I mean even in this HN thread tons of people are taking about how they wish the iOS app would have better backup and transfer functions. Something tells me they're not itching to transfer all those already deleted messages. And sure, maybe Recall ends up saving things longer than it was set for. Maybe Signal does as well. And once again, accessing all your Signal database doesn't even require system privileges just your local user account. Your browser can access all your Signal messages. Your chat app can access all your Signal messages. Your email client can access all your Signal messages. Your calculator app can access all your Signal messages. That videogame made by Tencent can access all your Signal messages. They don't even have to screengrab, they can just read them.
      - fwn 1y ago
        You should be able to access everything on your own computer - that is a good thing. The real problem with Recall is that Microsoft will access the data to apply some algorithmic secret sauce. The product manager already probably has all kinds of ideas for the future: targeting ads, upselling licenses, or making MS more attractive to law enforcement. Yes, there is a benefit for the user, like a nicer search or something, but that is relatively minor. ..because Microsoft is not your friend. This feature is born from a harvesting mindset. Regarding disappearing messages: I have two chats on WhatsApp where disappearing messages are turned off, and maybe a handful on Signal. It is actually less common to disable them on WhatsApp than on Signal, mainly because Signal forbids delete windows longer than four weeks. That is not long enough sometimes. I have no idea how our usage here ends up being so dramatically different. I don't even tend to talk about the feature with most contacts.
        vel0city 1y ago
        > Microsoft will access the data Incorrect. This runs locally. Microsoft is advertising the data just as much as you opening the file in notepad or browsing a folder in explorer. And once again I just point to all the people complaining about a lack of backup and weak transfer ability. They're not looking to backup a nearly empty history.
cookiengineer 1y ago
It's kind of funny that this argument always comes up when talking about Windows security. What if I told you that botched sandboxing by default is not the standard we should accept? And that Windows' lack of competence to isolate processes isn't even what the NT Kernel envisioned (see e.g. ReactOS)? I'd never run Windows as a host system, given the track record of how Microsoft deals with RCEs and privilege escalation issues that have been unfixed for decades at this point.
- vel0city 1y ago
  It's the same security for the Signal as on MacOS and Linux. Your user has full control to it, generally all processes running as you can see it and mess with it.
- didntcheck 1y ago
  * Arguing about what should be doesn't alter the facts of the current situation * It's unfair to single out Windows here, when other platforms are not much better. Mechanisms for stronger sandboxing and storage firewalling do exist on all platforms, but in practice these are barely used on desktops, and this is true across all three major OS families. E.g. Flatpaks exist, but I believe they still represent the minority of actual application installs And ironically Wayland also gets frequent, heavy criticism for doing the right thing here - treating screen or input capture as a privileged operation, rather than a default right of any random application you have running (though I agree they should have standardized an escape hatch earlier)
  - vrighter 1y ago
    I do not want stronger sandboxing for my apps. I'll only allow it to run on my machine if I trust it anyway. I'm not worried about my apps being able to read my data. If a piece of software doesn't do what I want safely and securely, then I don't try to duct-tape it into a sandbox that's regularly broken out of anyway. I remove and use other software. If flatpak/appimage are the only way to get a piece of software, I won't even waste my time evaluating it.
alexjurkiewicz 1y ago
Right, this feels like an entry to Raymond Chen's "it rather involved being on the other side of this airtight hatchway"! I have nothing against Signal implementing screenshot hiding. But it's not exactly fixing a gaping security hole.
ruined 1y ago
signal desktop keeps database keys in the os keystore via electron safestorage api on linux that’ll be kwallet or something, on mac it’s the keyring. it’s as secure as your password manager edit: okay, you’re right, on windows it’s useless lol https://www.electronjs.org/docs/latest/api/safe-storage https://www.electronjs.org/docs/latest/api/safe-storage > [on Windows] content is protected from other users on the same machine, but not from other apps running in the same userspace.
- lovetox 1y ago
  It's not different on Linux, every App can access any key in kwallet. To make this not possible the os would need to generate some kind of unique app id that can access only what it stored. This would probably result in a lot of lost passwords for normal users.
shakna 1y ago
Recall is encrypted with a key in the TPM. But getting access to that encrypted sqlite db is a yawn. Getting the key is harder, but possible. You can breach into Microsoft's group with a particular set of GPOs - if you can run a particular set of server commands on the local network. Signal data is encrypted at rest. The key is stored in the OS store - usually meaning the TPM. However, the key isn't in Microsoft's main grouping. To date, no one has extracted the Signal key this way. Other exploits are required. Signal being smaller than the whole of Microsoft, reduces the attack surface.
- vel0city 1y ago
  > no one has extracted the Signal key this way This is incorrect. Any process running as your user can trivially get the key.
- smileybarry 1y ago
  If Signal uses the Windows Data Protection API for saving/encrypting the key (and some data online suggests that it does), then it’s trivial to fetch it back with the same APIs if you’re running as the same user. (I use `keyring` on Windows to access the key(s) VMware Workstation uses to encrypt Windows 11 VM vTPMs) It’s kept secure by a chain of keys that may be backed by the TPM, but the security boundary is the user, not the app identity. IIRC Store/UWP apps may get their own boundary for credentials (due to how .appx is implemented).

advisedwang 1y ago

At least this gives forward secrecy, so if someone takes control of your computer they can only spy on signal messages AFTER that point, and can't access prior messages that Recall has captured.

vel0city 1y ago
This is only forward secrecy for messages that were deleted and would have been captured by Recall and are still within the snapshot history which has a maximum number of days. All the messages you've previously synced to the device exist in that Signal AppData directory and can be trivially searched and read by any application running as your user account. And all attachments are also just sitting there. For example: https://vmois.dev/query-signal-desktop-messages-sqlite/ https://vmois.dev/query-signal-desktop-messages-sqlite/
- acdha 1y ago
  Given how popular the disappearing messages feature is, a lot of messages are going to be deleted where Recall is a second, less tested copy of things which the user believes are gone. Given the past history of AI tools it seems dangerously likely that someone would find that their Recall history was retained longer than necessary or could be retrieved through some creative misuse of Recall which doesn’t require system access.
  - vel0city 1y ago
    > Given how popular the disappearing messages feature is, I don't think it's really that popular or extensively used. Most people I know who use signal use it pretty rarely. I'll turn it on when I'm about to send something sensitive, but generally it's not enabled. I've been using Signal since 2015 and I've probably only sent or received a hundred or so disappearing messages. I've sent and received many, many thousands of messages. And I mean even in this HN thread tons of people are taking about how they wish the iOS app would have better backup and transfer functions. Something tells me they're not itching to transfer all those already deleted messages. And sure, maybe Recall ends up saving things longer than it was set for. Maybe Signal does as well. And once again, accessing all your Signal database doesn't even require system privileges just your local user account. Your browser can access all your Signal messages. Your chat app can access all your Signal messages. Your email client can access all your Signal messages. Your calculator app can access all your Signal messages. That videogame made by Tencent can access all your Signal messages. They don't even have to screengrab, they can just read them.
    - fwn 1y ago
      You should be able to access everything on your own computer - that is a good thing. The real problem with Recall is that Microsoft will access the data to apply some algorithmic secret sauce. The product manager already probably has all kinds of ideas for the future: targeting ads, upselling licenses, or making MS more attractive to law enforcement. Yes, there is a benefit for the user, like a nicer search or something, but that is relatively minor. ..because Microsoft is not your friend. This feature is born from a harvesting mindset. Regarding disappearing messages: I have two chats on WhatsApp where disappearing messages are turned off, and maybe a handful on Signal. It is actually less common to disable them on WhatsApp than on Signal, mainly because Signal forbids delete windows longer than four weeks. That is not long enough sometimes. I have no idea how our usage here ends up being so dramatically different. I don't even tend to talk about the feature with most contacts.
      - vel0city 1y ago
        > Microsoft will access the data Incorrect. This runs locally. Microsoft is advertising the data just as much as you opening the file in notepad or browsing a folder in explorer. And once again I just point to all the people complaining about a lack of backup and weak transfer ability. They're not looking to backup a nearly empty history.

cookiengineer 1y ago

It's kind of funny that this argument always comes up when talking about Windows security. What if I told you that botched sandboxing by default is not the standard we should accept? And that Windows' lack of competence to isolate processes isn't even what the NT Kernel envisioned (see e.g. ReactOS)? I'd never run Windows as a host system, given the track record of how Microsoft deals with RCEs and privilege escalation issues that have been unfixed for decades at this point.

vel0city 1y ago
It's the same security for the Signal as on MacOS and Linux. Your user has full control to it, generally all processes running as you can see it and mess with it.
didntcheck 1y ago
* Arguing about what should be doesn't alter the facts of the current situation * It's unfair to single out Windows here, when other platforms are not much better. Mechanisms for stronger sandboxing and storage firewalling do exist on all platforms, but in practice these are barely used on desktops, and this is true across all three major OS families. E.g. Flatpaks exist, but I believe they still represent the minority of actual application installs And ironically Wayland also gets frequent, heavy criticism for doing the right thing here - treating screen or input capture as a privileged operation, rather than a default right of any random application you have running (though I agree they should have standardized an escape hatch earlier)
- vrighter 1y ago
  I do not want stronger sandboxing for my apps. I'll only allow it to run on my machine if I trust it anyway. I'm not worried about my apps being able to read my data. If a piece of software doesn't do what I want safely and securely, then I don't try to duct-tape it into a sandbox that's regularly broken out of anyway. I remove and use other software. If flatpak/appimage are the only way to get a piece of software, I won't even waste my time evaluating it.

alexjurkiewicz 1y ago

Right, this feels like an entry to Raymond Chen's "it rather involved being on the other side of this airtight hatchway"! I have nothing against Signal implementing screenshot hiding. But it's not exactly fixing a gaping security hole.

ruined 1y ago

signal desktop keeps database keys in the os keystore via electron safestorage api on linux that’ll be kwallet or something, on mac it’s the keyring. it’s as secure as your password manager edit: okay, you’re right, on windows it’s useless lol https://www.electronjs.org/docs/latest/api/safe-storage https://www.electronjs.org/docs/latest/api/safe-storage > [on Windows] content is protected from other users on the same machine, but not from other apps running in the same userspace.

lovetox 1y ago
It's not different on Linux, every App can access any key in kwallet. To make this not possible the os would need to generate some kind of unique app id that can access only what it stored. This would probably result in a lot of lost passwords for normal users.

shakna 1y ago

Recall is encrypted with a key in the TPM. But getting access to that encrypted sqlite db is a yawn. Getting the key is harder, but possible. You can breach into Microsoft's group with a particular set of GPOs - if you can run a particular set of server commands on the local network. Signal data is encrypted at rest. The key is stored in the OS store - usually meaning the TPM. However, the key isn't in Microsoft's main grouping. To date, no one has extracted the Signal key this way. Other exploits are required. Signal being smaller than the whole of Microsoft, reduces the attack surface.

vel0city 1y ago
> no one has extracted the Signal key this way This is incorrect. Any process running as your user can trivially get the key.
smileybarry 1y ago
If Signal uses the Windows Data Protection API for saving/encrypting the key (and some data online suggests that it does), then it’s trivial to fetch it back with the same APIs if you’re running as the same user. (I use `keyring` on Windows to access the key(s) VMware Workstation uses to encrypt Windows 11 VM vTPMs) It’s kept secure by a chain of keys that may be backed by the TPM, but the security boundary is the user, not the app identity. IIRC Store/UWP apps may get their own boundary for credentials (due to how .appx is implemented).