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| 1 | + ---===[ Dasharo Security Bulletin 001 ]===--- |
| 2 | + |
| 3 | + Wrong Intel Boot Guard fusing prevents further updates |
| 4 | + |
| 5 | +Version |
| 6 | +------- |
| 7 | + |
| 8 | +* Bulletin: DSB-001 |
| 9 | +* Published: 2025-12-22 |
| 10 | +* Updated: 2025-12-22 |
| 11 | +* Version: 1 |
| 12 | + |
| 13 | +Affected configurations |
| 14 | +----------------------- |
| 15 | + |
| 16 | +NovaCustom V540TU and V560TU devices that have undergone the additional Dasharo |
| 17 | +TrustRoot fusing process (either manually, or via Dasharo Tools Suite) between |
| 18 | +2025-10-24 and 2025-12-05. |
| 19 | + |
| 20 | +This process is not something that is automatically triggered during regular |
| 21 | +firmware updates. It requires opt-in user interaction with several warnings [1]. |
| 22 | +If you are not sure whether you have done it - you most likely have not. You may |
| 23 | +follow this document further to learn how to verify this. |
| 24 | + |
| 25 | +Devices that have not undergone the fusing procedure, are not affected. |
| 26 | + |
| 27 | +User action |
| 28 | +----------- |
| 29 | + |
| 30 | +* Verify the Intel Boot Guard key on your fused laptop, using Dasharo Tools |
| 31 | + Suite [2] |
| 32 | +* Contact Dasharo support at support[at]dasharo.com if you have fused the |
| 33 | + device by yourself, presenting output from the above tool stating |
| 34 | + that fused key does not match to the expected one. |
| 35 | +* If your device is affected, ensure that any data protected by the TPM is |
| 36 | + recoverable before proceeding with mainboard replacement. Further details are |
| 37 | + provided in the Impact section. |
| 38 | + |
| 39 | +Workarounds |
| 40 | +----------- |
| 41 | + |
| 42 | +No workarounds are available. |
| 43 | + |
| 44 | +Details |
| 45 | +------- |
| 46 | + |
| 47 | +During the release of Dasharo v1.0.0 (coreboot+UEFI) for NovaCustom Meteor Lake |
| 48 | +iGPU laptops (models V540TU [3] and V560TU [4]), a human error in the artifact |
| 49 | +publication process resulted in publishing firmware binaries being signed with |
| 50 | +a developer key instead of the correct client production key. This caused an |
| 51 | +irreversible change of fuses inside the SoC, locking the firmware with a key |
| 52 | +that we cannot reproduce for future updates. |
| 53 | + |
| 54 | +Affected binaries were immediately removed from the public distribution to |
| 55 | +prevent any further devices from being impacted. The ability for users to |
| 56 | +perform Dasharo TrustRoot fusing by themselves on these models has been |
| 57 | +temporarily suspended. |
| 58 | + |
| 59 | +Impact |
| 60 | +------ |
| 61 | + |
| 62 | +We have conducted a thorough technical analysis. Unfortunately, for the devices |
| 63 | +that have already been fused with these incorrect binaries, the situation is |
| 64 | +irreversible via software. Because the hardware is now locked to a |
| 65 | +non-production key, these units cannot accept any future firmware updates or |
| 66 | +security patches. This means that to restore full functionality, |
| 67 | +maintainability, and long-term security of these devices, the mainboards must be |
| 68 | +physically replaced. |
| 69 | + |
| 70 | +The replacement mainboard will include a new TPM (Trusted Platform Module). |
| 71 | +Consequently, any secrets previously stored in the TPM, such as disk encryption |
| 72 | +keys, will be lost during this process. |
| 73 | + |
| 74 | +Users must ensure that any data protected by TPM-backed encryption is |
| 75 | +recoverable before the mainboard replacement. In particular, recovery keys (for |
| 76 | +example, LUKS or BitLocker recovery keys) should be securely stored outside the |
| 77 | +system and verified prior to shipping the motherboard. |
| 78 | + |
| 79 | +Patching |
| 80 | +-------- |
| 81 | + |
| 82 | +* No firmware binary modification can fix the problem. |
| 83 | +* 3mdeb and NovaCustom are coordinating mainboards replacement program for all |
| 84 | + affected devices. |
| 85 | +* Reinforcing of existing automation protocols was applied to the 3mdeb internal |
| 86 | + provisioning process. This should prevent future occurrences of publication of |
| 87 | + incorrect firmware binary. |
| 88 | +* Public verification mechanisms updated: UEFI Capsule Update mechanism [5], [6] |
| 89 | + and Dasharo Tools Suite utility since v2.7.2 [7], [8] now block updates if the |
| 90 | + firmware is not signed with the correct Intel Boot Guard key. |
| 91 | + |
| 92 | +Credits |
| 93 | +------- |
| 94 | + |
| 95 | +Found internally by the Dasharo Team. |
| 96 | + |
| 97 | +References |
| 98 | +---------- |
| 99 | + |
| 100 | +[1] https://docs.dasharo.com/guides/cpu-fusing |
| 101 | +[2] https://docs.dasharo.com/dasharo-tools-suite/documentation/features/#verify-intel-boot-guard-key |
| 102 | +[3] https://docs.dasharo.com/variants/novacustom_v540tu/releases/#v100-2025-09-18 |
| 103 | +[4] https://docs.dasharo.com/variants/novacustom_v560tu/releases/#v100-2025-09-18 |
| 104 | +[5] https://github.com/Dasharo/coreboot/pull/818 |
| 105 | +[6] https://github.com/Dasharo/edk2/pull/285 |
| 106 | +[7] https://github.com/Dasharo/dts-scripts/pull/128/files |
| 107 | +[8] https://github.com/Dasharo/meta-dts/releases/tag/v2.7.2 |
| 108 | + |
| 109 | +The Dasharo Security Team |
| 110 | +https://docs.dasharo.com/security/ |
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