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MCU

Sonix SN32F707

debug connector

from the SIM card side (left), to the switch (right)

GND
SWDCLK
SWDIO
+3.3V

GPRS module: Quectel M26

on USART1 (9600,N,8,1) turn on with GPIO P2.7

useul commands

AT+QIREGAPP="TM",,
AT+QIOPEN="TCP","129.6.15.28",13
AT+QNTP="193.204.114.233",123

GPS

UBLOX UBX-G70xx on USART0 (9600,N,8,1) turn on with GPIO P2.4

infos at start::

GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
GPTXT,01,01,02,HW  UBX-G70xx   00070000 *77
GPTXT,01,01,02,ROM CORE 1.00 (59842) Jun 27 2012 17:43:52*59
GPTXT,01,01,02,PROTVER 14.00*1E
GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*20
GPTXT,01,01,02,ANTSTATUS=DONTKNOW*33
GPTXT,01,01,02,LLC FFFFFFFF-FFFFFFFD-FFFFFFFF-FFFFFFFF-FFFFFFF9*53
GPTXT,01,01,02,ANTSTATUS=INIT*25
GPTXT,01,01,02,ANTSTATUS=OK*3B

Photos from FCC

https://fccid.io/2AI2O-OC30/Internal-Photos/Internal-photos-3426571

Mobile provider

https://www.hologram.io

Accelerometer: LIS3DH

example code

Cold boot stepping

apparently the instruction at 0x2b8 is

ldr r3,[r4,#12]

putting an adress minus 12 in r4 it is posible to read memory at the specified address.

This makes a "cold boot stepping" attack possible.

See Bypassing CRP on Microcontrollers by Andrew Tierney

Other components

Routines of the bootloader (0x1fff0000)

0x1fff0318 eraseFlash(r0=address)
0x1fff033c writeFlash(r0=address,r1=bytes,r2=data address)

Curiosities

In the original firmware you can find a string containing coordinate expressed according to the NMEA standard (2237.75314,N,11408.62621,E). The point to somewhere in Shenzen 1500m from the site of Omni Intelligent Technology Co.

EEPROM dump

Arduino program adapted from https://www.insidegadgets.com/2010/12/22/reading-data-from-eeprom-i2c-on-a-pcb/ (rows containig only FF are not shown)

0020|AA 55 55 AA 68 6F 6C 6F 67 72 61 6D 00 FF FF FF |.UU.hologram....|
0040|FF FF FF FF 30 30 30 30 00 FF 31 32 33 34 35 36 |....0000..123456|
0050|00 FF FF FF 30 00 FF FF 31 32 30 2E 32 34 2E 32 |....0...120.24.2|
0060|32 38 2E 31 39 39 00 FF FF FF FF FF FF FF FF FF |28.199..........|
0090|FF FF FF FF FF FF FF FF 39 36 36 36 00 FF FF FF |........9666....|
00A0|4F 4D 00 FF FF FF FF FF 79 4F 54 6D 4B 35 30 7A |OM......yOTmK50z|
00B0|00 FF FF FF 56 67 7A 37 00 FF FF FF 04 00 FF FF |....Vgz7........|
00C0|00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
0400|55 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF |U...............|

MCU