text
stringlengths
0
1.99k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==
|=-----------------------------------------------------------------------=|
|=---------------------=[ 6 - MMIO in the Middle ]=----------------------=|
|=-----------------------------------------------------------------------=|
|=----------------------------=[ b1ack0wl ]=-----------------------------=|
|=-----------------------------------------------------------------------=|
--[ Table of Contents
0 - Introduction
1 - What sparked this research
2 - Looking into Das U-Boot
3 - Initial Testing
4 - Using Qemu to record MMIO transactions
5 - Discoveries
6 - Failed idea(s)
7 - Give this a try yourself!
--[ 0 - Introduction
System on Chips (SoCs) are very common in embedded devices, ranging from
cell phones to cheap smart devices. These chips contain many subcomponents
within them such as flash memory, network chips, modems, ...etc. These
subcomponents are interacted with via Memory Mapped Input Output regions
(MMIO) which is a fancy way of saying "Memory Address 0x00000004 is mapped
to register 'X' for component 'Y'.
The target for this article is the TP-Link WR940N wireless router. This
device has a fairly old processor in it, the "TP9343", which is actually
a Qualcomm Atheros QCA956x SoC. Even though the target device in this
article is outdated, the technique I am about to describe can be applied
to different types of embedded devices where the bootloader can easily be
changed, or has the ability to read and write to physical memory.
--[ 1 - What sparked this research