[…]Today we’re excited to announce Asylo (Greek for “safe place”), a new open-source framework that makes it easier to protect the confidentiality and integrity of applications and data in a confidential computing environment. Asylo is an open-source framework and SDK for developing applications that run in trusted execution environments (TEEs). TEEs help defend against attacks targeting underlying layers of the stack, including the operating system, hypervisor, drivers, and firmware, by providing specialized execution environments known as “enclaves”. TEEs can also help mitigate the risk of being compromised by a malicious insider or an unauthorized third-party. Asylo includes features and services for encrypting sensitive communications and verifying the integrity of code running in enclaves, which help protect data and applications.[…]
Unbox Your Phone — Part I.
This is the first part of a blog series about reverse engineering and exploiting Samsung’s TrustZone. Following parts in the series so far: 2, 3. This first post covers the basics of the architecture. All of this is public info, nothing new, all of it has been covered in bits and pieces in various publications before. Some of it comes from Trustonic/Samsung materials, some of it from open source software, and some of it from the few great instances of prior research. It’s here as an intro, for completeness. Later in the series, I summarize the reverse engineering results and explain the vulnerabilities that I have found.[…]
Exploiting Qualcomm EDL Programmers (1): Gaining Access & PBL Internals
By Roee Hay (@roeehay) & Noam Hadad
January 22, 2018
* QPSIIR-909, ALEPH-2017029, CVE-2017-13174, CVE-2017-5947
There are many guides across the Internet for ‘unbricking’ Qualcomm-based mobile devices. All of these guides make use of Emergency Download Mode (EDL), an alternate boot-mode of the Qualcomm Boot ROM (Primary Bootloader). To make any use of this mode, users must get hold of OEM-signed programmers, which seem to be publicly available for various such devices. While the reason of their public availability is unknown, our best guess is that these programmers are often leaked from OEM device repair labs. Some OEMs (e.g. Xiaomi) also publish them on their official forums. […] In this 5-part blog post we discuss the security implications of the leaked programmers. The first part presents some internals of the PBL, EDL, Qualcomm Sahara and programmers, focusing on Firehose. In Part 2, we discuss storage-based attacks exploiting a functionality of EDL programmers – we will see a few concrete examples such as unlocking the Xiaomi Note 5A (codename ugglite) bootloader in order to install and load a malicious boot image thus breaking the chain-of-trust. Part 3, Part 4 & Part 5 are dedicated for the main focus of our research – memory based attacks. In Part 3 we exploit a hidden functionality of Firehose programmers in order to execute code with highest privileges (EL3) in some devices, allowing us, for example, to dump the Boot ROM (PBL) of various SoCs. We then present our exploit framework, firehorse, which implements a runtime debugger for firehose programmers (Part 4). We end with a complete Secure-Boot bypass attack for Nokia 6 MSM8937, that uses our exploit framework. We achieve code execution in the PBL (or more accurately, in a PBL clone), allowing us to defeat the chain of trust, gaining code execution in every part of the bootloader chain, including TrustZone, and the High Level OS (Android) itself.
The merit of our research is as follows:
* We describe the Qualcomm EDL (Firehose) and Sahara Protocols. (Part 1)
* We created firehorse, a publicly available research framework for Firehose-based programmers, capable of debugging/tracing the programmer (and the rest of the bootloader chain, including the Boot ROM itself, on some devices). (Part 3 & Part 4)
* We obtained and reverse-engineered the PBL of various Qualcomm-based chipsets (MSM8994/MSM8917/MSM8937/MSM8953/MSM8974) using the Firehose programmers and our research framework. (Part 3)
* We obtained the RPM & Modem PBLs of Nexus 6P (MSM8994). (Part 3)
* We managed to unlock & root various Android Bootloaders, such as Xiaomi Note 5A, using a storage-based attack only. (Part 2)
* We managed to manifest an end-to-end attack against our Nokia 6 device running Snapdragon 425 (MSM8937). We believe this attack is also applicable for Nokia 5, and might be even extensible to other devices, although unverified. (Part 5)
Research & Exploitation framework for Qualcomm EDL Firehorse programmers
Exploiting Qualcomm EDL Programmers (1): Gaining Access & PBL Internals
Exploiting Qualcomm EDL Programmers (2): Storage-based Attacks & Rooting
Exploiting Qualcomm EDL Programmers (3): Memory-based Attacks & PBL Extraction
Exploiting Qualcomm EDL Programmers (4): Runtime Debugger
Exploiting Qualcomm EDL Programmers (5): Breaking Nokia 6’s Secure Boot
34C3 Tool Release: Cachegrab
Today, NCC Group is releasing Cachegrab, a tool designed to help perform and visualize trace-driven cache attacks against software in the secure world of TrustZone-enabled ARMv8 cores. These cache attacks, as well as other microarchitectural attacks on secure computing environments, were presented at the 34th Chaos Communication Congress. There are two key properties of many TrustZone implementations that make the attacks within Cachegrab feasible. First, the secure world and non-secure world often share the caches within a processor. This means that when software executes in the secure world, it affects the presence or absence of non-secure world entries within the shared cache. Second, privileged users in the non-secure world are able to use privileged instructions to interleave attacker and victim processes, as well as determine what non-secure data has been evicted from the cache.[…]
ARM has announced a Platform Security Architecture.
As well, they’ve announced the ARM CryptoIsland family of TrustZone family.
And they’ve announced the ARM CoreSight SDC-600 Secure Debug Channel, which provides a dedicated path to a debugged system for authenticating debug accesses.
vTZ: Virtualizing ARM TrustZone
Zhichao Hua, Jinyu Gu, Yubin Xia, Haibo Chen, Binyu Zang, Haibing Guan
ARM TrustZone, a security extension that provides a secure world, a trusted execution environment (TEE), to run security-sensitive code, has been widely adopted in mobile platforms. With the increasing momentum of ARM64 being adopted in server markets like cloud, it is likely to see TrustZone being adopted as a key pillar for cloud security. Unfortunately, TrustZone is not designed to be virtualizable as there is only one TEE provided by the hardware, which prevents it from being securely shared by multiple virtual machines (VMs). This paper conducts a study on variable approaches to virtualizing TrustZone in virtualized environments and then presents vTZ, a solution that securely provides each guest VM with a virtualized guest TEE using existing hardware. vTZ leverages the idea of separating functionality from protection by maintaining a secure co-running VM to serve as a guest TEE, while using the hardware TrustZone to enforce strong isolation among guest TEEs and the untrusted hypervisor. Specifically, vTZ uses a tiny monitor running within the physical TrustZone that securely interposes and virtualizes memory mapping and world switching. vTZ further leverages a few pieces of protected, self-contained code running in a Constrained Isolated Execution Environment (CIEE) to provide secure virtualization and isolation among multiple guest TEEs. We have implemented vTZ on Xen 4.8 on both ARMv7 and ARMv8 development boards. Evaluation using two common TEE-kernels (secure kernel running in TEE) such as seL4 1 and OP-TEE shows that vTZ provides strong security with small performance overhead.