7 ms·

> knowledge of the keys is a primary requirement for target card compromise Not claiming to be an expert, but this seems like a very big qualification. Can som

> knowledge of the keys is a primary requirement for target card compromise Not claiming to be an expert, but this seems like a very big qualification. Can someone put this into context for me? If you stole my private key for my PGP key, you would absolutely be able to sign messages as me.

lxgr 1y ago
They were apparently able to extract an eUICC's private key: > As a result of eUICC compromise, we were able to extract private ECC key for the certificate identifying target GSMA card. This is supposed to be impossible, even with knowledge of SAT applet management keys. (In other words, individual eSIM profiles are still not supposed to be able to extract private eSIM provisioning keys from any eUICC.) In the security architecture of eSIMs, compromising any eUICC's key means that an attacker can obtain the raw eSIM profile data from any SM-DP trusting it (which would be any, if it chains up to a CA part of the GSMA PKI) and do things that are supposed to be impossible, such as simultaneously installing one profile on multiple devices, or extract secret keys from a profile and then "put it back" to the SM-DP, let the legitimate user download it, and intercept their communications.
- ImPostingOnHN 1y ago
  Let's assume I have the following philosophy: My phone, my sim or esim, and anything else which I have purchased and is in my possession, belongs to me. Being able to retrieve keys to things I own, and do whatever I want with them, seems fine. If the key to my car says "do not duplicate", I should be nonetheless able to duplicate it, because I own the car and the key. If I want to run my same profile or eSIM on multiple devices, I get that the cell company doesn't like that, but I do, so I wouldn't consider that a harm to me. Given that assumption, this vulnerability/jailbreak/rooting of something I own seems less significant to me. I think, however, that I may be misunderstanding the attack. Is this possible to perform against somebody else for whom I will never have physical possession of the phone? Or for someone else to perform it against me, without ever having physical possession of my phone? It sounded like maybe a test profile was left enabled, which allows anyone to send an SMS-PP message to any phone, telling it to install an applet which compromises the phone/eUICC/eSIM's keys. Did I follow that right?
  - lxgr 1y ago
    > Let's assume I have the philosophy that my phone, my sim or esim, and anything else which I have purchased and is in my possession, belongs to me. Then you can't use eSIMs as specified. eUICCs are an implementation of trusted computing. > I think I may be misunderstanding the attack, though. Is this possible to perform against somebody else for whom I will never have physical possession of the phone? Or for someone else to perform it against me, without ever having physical possession of my phone? In a non-broken eSIM security architecture, eSIM profiles are singletons, i.e. they can only be installed on any given eUICC at one time. At install time, the SM-DP decrements the logical "remaining installs" counter from 1 to 0; at uninstall time, it goes back up to 1. This of course only works if the eUICC's assertion of "I deleted eSIM profile x" is trustworthy, hence it requires trusted computing. A different security architecture not relying on trusted computing is of course possible to imagine, but that's not what current networks assume.
    - ImPostingOnHN 1y ago
      > Then you can't use eSIMs as specified. Could you elaborate here, please? I am kind of ignorant on this topic. Using an exploit to root my phone results in not using the phone "as specified", but it still works, and it's okay with me, because I own it. It sounded like the concerns you had were ones the network operator should be concerned with. Suppose I don't care about their concerns unless they result in my stuff being compromised*. Are you saying that it breaks the security in a way that someone who doesn't own my phone and doesn't have physical access to my phone can compromise my phone and/or my eSIM? * - for the purposes of simplifying discussion, I'm dismissing the possibility that the network operator throws up their hands and entirely stops using/allowing eSIMs because they can't control everything
      - lxgr 1y ago
        The eSIM lives in dedicated, tamper-proof hardware inside your phone, separate from the application processor OS (which would be the domain of rooting) or often even the baseband. Under the eSIM security model, it holds keys that the device owner is not supposed to be able to extract, not even when they're willing to physically dismantle the chip holding it. > Are you saying that it breaks the security in a way that someone who doesn't own my phone and doesn't have physical access to my phone can compromise my phone and/or my eSIM? Yes, it does: Currently, providers assume that any eSIM honors the "singleton contract" described above. One that does not, e.g. one simulated in software using keys extracted from a physical trusted eUICC, could be used to mount the following attack: 1. Intercept the eSIM setup QR code (which contains two things: the URL of the SM-DP and a secret profile identifier) 2. Install the eSIM profile on their "software eSIM". 3. Report the eSIM as successfully deleted to the SM-DP, which now considers it available for installs again. 4. You, the legitimate owner of the eSIM, now install it on your unmodified eUICC in your phone and go about your day. 5. One day, ideally when your legitimate SIM is offline, the attacker inserts their eSIM into a phone and intercepts phone calls and SMS to your number, initiates expensive toll calls etc. One solution here would be to never allow re-installs of the same eSIM profile, which some providers already do, but I personally don't like eSIM profiles managed that way, as it requires me to interact with carrier support and often even pay money just to transfer an eSIM to a new device.

lxgr 1y ago

They were apparently able to extract an eUICC's private key: > As a result of eUICC compromise, we were able to extract private ECC key for the certificate identifying target GSMA card. This is supposed to be impossible, even with knowledge of SAT applet management keys. (In other words, individual eSIM profiles are still not supposed to be able to extract private eSIM provisioning keys from any eUICC.) In the security architecture of eSIMs, compromising any eUICC's key means that an attacker can obtain the raw eSIM profile data from any SM-DP trusting it (which would be any, if it chains up to a CA part of the GSMA PKI) and do things that are supposed to be impossible, such as simultaneously installing one profile on multiple devices, or extract secret keys from a profile and then "put it back" to the SM-DP, let the legitimate user download it, and intercept their communications.

ImPostingOnHN 1y ago
Let's assume I have the following philosophy: My phone, my sim or esim, and anything else which I have purchased and is in my possession, belongs to me. Being able to retrieve keys to things I own, and do whatever I want with them, seems fine. If the key to my car says "do not duplicate", I should be nonetheless able to duplicate it, because I own the car and the key. If I want to run my same profile or eSIM on multiple devices, I get that the cell company doesn't like that, but I do, so I wouldn't consider that a harm to me. Given that assumption, this vulnerability/jailbreak/rooting of something I own seems less significant to me. I think, however, that I may be misunderstanding the attack. Is this possible to perform against somebody else for whom I will never have physical possession of the phone? Or for someone else to perform it against me, without ever having physical possession of my phone? It sounded like maybe a test profile was left enabled, which allows anyone to send an SMS-PP message to any phone, telling it to install an applet which compromises the phone/eUICC/eSIM's keys. Did I follow that right?
- lxgr 1y ago
  > Let's assume I have the philosophy that my phone, my sim or esim, and anything else which I have purchased and is in my possession, belongs to me. Then you can't use eSIMs as specified. eUICCs are an implementation of trusted computing. > I think I may be misunderstanding the attack, though. Is this possible to perform against somebody else for whom I will never have physical possession of the phone? Or for someone else to perform it against me, without ever having physical possession of my phone? In a non-broken eSIM security architecture, eSIM profiles are singletons, i.e. they can only be installed on any given eUICC at one time. At install time, the SM-DP decrements the logical "remaining installs" counter from 1 to 0; at uninstall time, it goes back up to 1. This of course only works if the eUICC's assertion of "I deleted eSIM profile x" is trustworthy, hence it requires trusted computing. A different security architecture not relying on trusted computing is of course possible to imagine, but that's not what current networks assume.
  - ImPostingOnHN 1y ago
    > Then you can't use eSIMs as specified. Could you elaborate here, please? I am kind of ignorant on this topic. Using an exploit to root my phone results in not using the phone "as specified", but it still works, and it's okay with me, because I own it. It sounded like the concerns you had were ones the network operator should be concerned with. Suppose I don't care about their concerns unless they result in my stuff being compromised*. Are you saying that it breaks the security in a way that someone who doesn't own my phone and doesn't have physical access to my phone can compromise my phone and/or my eSIM? * - for the purposes of simplifying discussion, I'm dismissing the possibility that the network operator throws up their hands and entirely stops using/allowing eSIMs because they can't control everything
    - lxgr 1y ago
      The eSIM lives in dedicated, tamper-proof hardware inside your phone, separate from the application processor OS (which would be the domain of rooting) or often even the baseband. Under the eSIM security model, it holds keys that the device owner is not supposed to be able to extract, not even when they're willing to physically dismantle the chip holding it. > Are you saying that it breaks the security in a way that someone who doesn't own my phone and doesn't have physical access to my phone can compromise my phone and/or my eSIM? Yes, it does: Currently, providers assume that any eSIM honors the "singleton contract" described above. One that does not, e.g. one simulated in software using keys extracted from a physical trusted eUICC, could be used to mount the following attack: 1. Intercept the eSIM setup QR code (which contains two things: the URL of the SM-DP and a secret profile identifier) 2. Install the eSIM profile on their "software eSIM". 3. Report the eSIM as successfully deleted to the SM-DP, which now considers it available for installs again. 4. You, the legitimate owner of the eSIM, now install it on your unmodified eUICC in your phone and go about your day. 5. One day, ideally when your legitimate SIM is offline, the attacker inserts their eSIM into a phone and intercepts phone calls and SMS to your number, initiates expensive toll calls etc. One solution here would be to never allow re-installs of the same eSIM profile, which some providers already do, but I personally don't like eSIM profiles managed that way, as it requires me to interact with carrier support and often even pay money just to transfer an eSIM to a new device.