This summer at Black Hat, we have published research about exploiting Huawei basebands (video recording also available here). The remote code execution attack surface explored in that work was the Radio Resource stack’s CSN.1 decoder. Searching for bugs in CSN.1 decoding turned out to be very fruitful in the case of Huawei’s baseband, however, they were not the only vendor that we looked at - or that had such issues. Around at the same time that we investigated Huawei’s baseband, we also looked into the same attack surface in the baseband of MediaTek Helio chipsets. As the timelines in our advisories (1, 2, 3, 4) show, these vulnerabilities were reported way back in December 2019 and the MediaTek security advisories were released in September 2021 initially and updated in January 2022.
Recently we have presented our research on the remote exploitation of Huawei basebands at Black Hat USA 2021. As part of our findings, we have identified several bootloader vulnerabilities in Huawei Kirin chipsets. In addition to that publication, we have also recently disclosed an additional bootrom vulnerability (CVE-2021-22429) in Huawei Kirins. As it has been publicized, many of these bootloader vulnerabilities were present in bootrom code. As such, it can come as a surprise that Huawei in fact created a mitigation which was published just before Black Hat, in a July OTA update (updates started from June 29th, to be precise).
Summary In this advisory we are disclosing a vulnerability in the Huawei Over-The-Air (OTA) update implementation that allows bypassing SSL protections and execute a Man-In-The-Middle attack. The vulnerability was fixed in March 2022. Vulnerability Details Huawei devices - both those running Android and those running HarmonyOS - use Huawei’s custom implementation for applying OTA updates. OTA updates are packaged into a zip container. The update mechanism has several checks that are meant to ensure the authenticity of OTA images before they are applied: the over-the-air download is supposed to happen over a secure connection to prevent Man-In-The-Middle attacks, the zip file has a cryptographic signature that is verified by the update process, and finally the contents of the zip file include further authentications tags.
Summary There is a vulnerability in the Huawei Kirin SoC’s DDR Controller (DMSS) Access Permission system which allows the baseband to bypass the Baseband’s MPU memory protections and circumvent RO and NX protections. The vulnerability was fixed in February 2022. Vulnerability Details CVE-2021-22430 is a vulnerability in the Huawei Kirin SoC’s basebands which allowed to circumvent MPU restrictions. The vulnerability in CVE-2021-22430 was that MPU configuration was restored from a writable table for sleep cycles and therefore overwriting the cached entries resulted in new settings taking effect. This worked because the implementation normally only wrote the table once (not every time the core went to sleep) but restored the MPU configuration from it every time it was woken up.