Questions tagged [arm]

A family of instruction set architectures based on a RISC architecture developed by British company ARM Holdings. Heavily used in embedded devices such as mobile phones, tablets, set-top boxes, ...

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Instruction trace using frida in android emulator

i have a emulator named "Ldplayer" in my windows os and I'm trying to log all instructions executed by the app that uses ARM JNI libraries. basically, the app is running in an x86 emulator ...
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63 views

ARM7 32-bit Branch Offset Calculator

I need to patch an arm7 program by replacing this fopen function by another function. .text:00018D68 52 D7 FF EB BL fopen ... .plt:0000EAB8 ; FILE *fopen(const ...
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Replacing bytes from start of every function with IDA Pro

I want to fix a .plt segment in IDA Pro by replacing 12 bytes from start of every function in the .plt segment with the ones I specify. I want to just make each function return so I'm replacing ...
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61 views

Immediate offset LDR in presumed malloc function looks wrong in static analysis

I am attempting to disassemble a ROM image for a BCM4366C [1] after reading a blog post where researchers reversed some other Broadcom chips [2] . I have analyzed the ROM image in Ghidra and I have ...
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474 views

Having hard time analyzing stripped code

This is my first time doing RE on a statically linked and stripped binary with ghidra. And I'm having a really hard time analyzing what function does what just by looking the decompiled code present ...
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ARM 20-pin JTAG header?

I'm trying to find the JTAG header for an Intel X Scale (ArmV5) PXA270 board. I found and populated a 20-pin header: but JTAGulator doesn't think it has a valid combination of TDI/TDO/TMS/TCK on ...
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67 views

I have a two pin debug interface, confused on how to use it

I'm very much on the software side of things so I'm super inexperienced with debugging hardware. A custom processor I'm working with gives 2 debug pins, and given that it's an ARM system I suspect it ...
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1answer
160 views

Is Ghidra's decompilation of ARMv7 strb.w instruction broken?

I'm currently disassembling some firmware, when I stumbled across the following code snippet produced by Ghidra (the names are already my own ones): void memset(byte *addr,byte value,int count) ...
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477 views

ARM bx instruction branches to address not specified as argument

I'm debugging an ARM cortex M4 (STM32F4) running FreeRTOS. Inside the assembly FreeRTOS function vPortSVCHandler, there's a branch instruction bx r14 using GDB, I step through instruction by ...
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1answer
95 views

Issue understanding simple ARM ASM function

I'm a little stuck trying to understand this simple piece of code. It get's a number in R0. The first part seems to be a R0 = abs(R0), but then it get's more difficult. The number of leading zeros is ...
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35 views

ARMv7 Word Patch (CBZ)

I'm disassembling an iPhone app I'm trying to batch the instruction CBZ -> CBNZ Instruction Code: D9 09 00 34 As per my understanding, CBZ will jump to the address if value of register is 0 I have ...
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ARM chip gpio/ identification from firmware code

Device: i was able to recover bricked Chinese IOT a Sous Vide cooker. Replaced damaged capacitor. it works. it has ARM soc/mcu/processor WI-FI (broadcom) LCD touch screen + 16bit STM mcu. EEPROM ...
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Why use MOV R0, R3 and then MOV R3, R0 (thus back and forth)

I have a static library archive which I try to understand. First I use 'ar' to extract the object files. The object files ar "ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), not stripped" ...
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1answer
302 views

IDA Pro: How to change segment register value

For a specific Android library that I have loaded into IDA, I want to switch the THUMB/ARM mode to ARM, no matter the consequences that this is going to have to the code. Is there a way to efficiently ...
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37 views

finding specific string in ios dyld_shared_cache

Im trying to find the library inside a dyld cache that contains a specific string. I grepped the cache file and for the offset of the string, however when im throwing the cache file to ida non of the ...
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1answer
309 views

Recognize binary architecture

I have binary that run on Arm Thumb cpu, in embedded devive that not running Linux. When I tried to run bimwalk or file ,and even open it with Ida ,but they didn't find out that this binary run on ...
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492 views

What does this decompiled line mean?

__dest = (byte *)(**(code **)(*plVar5 + 0x10))(plVar5,(ulonglong)(numBytes + 1)); memcpy(__dest,param_2,numBytes + 1); Can someone please explain what the first line does step by step? I get that ...
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131 views

In IDA, cannot find xrefs to string in ARM little-endian bootloader/firmware

In this firmware that is ARM Little endian. There is two strings : 0x00006953 : Foretrex 701 0x00006960 : Foretrex 601 The issue, is there is no direct Xreft to any of thoses strings ? For the ...
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Find vulnerabilities in ARM IoT device

I have an ARM IoT device with a web interface, and I have the binary of this device open in Ida Pro. I looking for vulnerabilities in the webserver binary that can be exploited to run commands or ...
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1answer
309 views

Find all syscall in statically Arm Binary

What is the easy and fast way to find all syscall in statically Arm binary ? Is there any Ida plugin that do that?
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181 views

Reverse engineering MCU with "poor" datasheet

I'm reverse engineering a chinese MCU. The datasheet for this chip is pretty poor, they left out important things like memory map, block diagrams ecc... so i got stuck. This is what i've done: I got ...
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2answers
2k views

IDA Freeware 7.0 disassemble ARM .so file

I have a .so file from an android app, and I want to disassemble it with IDA. However I get the error: The processor type 'arm' is not included in the installed version of IDA. IDA Version: Freeware ...
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3answers
922 views

Reverse engineer .so file from android app with radare2

I have a .so file from an android app, and I know how to list all functions in IDA Pro. How can I do this with radare2?
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How to see assembly of main function?

How can I dump the assembly of main function of binary(not striped) in ubuntu? I want to see the assembly command and the hex value of this command There are 1 binary for arm and 1 binary for x86
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ARMv8 (AArch64, ARM64) opcodes list

I'm sorry for such as questions where answer would seem to be easily searched in google... Some time ago I have seen table/list of ARMv8 instructions with opcodes and it was perfect, but I lost link. ...
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How to proceed after running binwalk on this firmware?

I'm trying to access the firmware from the .bin in this archive: http://mydjiflight.dji.com/file/links/OSMO_ACTION_V17020_20191203_ZIP So far I've used binwalk and gotten the following output: ...
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146 views

Detecting libc function with IDA

I have binary than running on Arm , static and striped. I don't know which compiler compiled this binary. How can I identify function like fread sleep printf ioctl
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1answer
1k views

LDR specifier combination UXTW

Sorry, if this question seems stupid, but I am new in arm64 and next 2 assembly lines seriously damaged my brain: LDR W0, [X30,W0,UXTW#2] ADD X30, X30, W0,UXTW I have readed ...
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274 views

Patch Arm binary with Ida

In Ida I can patch binary that run on x86 , but not binary that run on Arm. How can I simply patch binary , change assembly(not only hex) and save to new binary file
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1answer
217 views

reverse engineering hi3516ev200

I am new to reverse engineering and will describe my situation thus far. In short, I am looking for some tips on what to do next to gain access to a piece of hardware I am playing with. I bought a ...
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60 views

Bin patching Arm7tdmi CRC32?

Ok so I am total noob here. I wanted to play with the bin from an instrument cluster I work on a lot. I was able to pull the bin off the MCU with a J-link. If I erase the chip and flash it with a bin ...
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1answer
99 views

IDA - ObjC - Meaning of _BYTE and dword_0?

This is my first experience disassembling/reverse engineering, and am having a bit of difficulty keeping up. For reference, I'm trying to uncover the inner workings of a pretty good library in my ...
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364 views

How to Modify CBZ Branch in ARM64?

If I want after running the CBZ W0, loc_C5C8 command Run to the ADRP X8,#selRef_curent_version@PAGE command regardless of the condition (in picture), what should I do?
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192 views

Reversing a firmware update for an LG HTS

I'm trying to reverse a firmware update for an LG Home Theater BH7220, and I've hit a brick wall. This HTS has a main chip from LG referred to as "BH7000:1165" in the schematics. The chip has the ...
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3answers
345 views

Strange vtable setup in constructor disassembly

In a program I'm trying to recover data structures I've discovered the following strange (ARM) disassembly code: ctor_1: ldr r1, =vtable_base str r1, [r0] ;r0 always contains ...
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139 views

Strange behaviour debugging Android ARM binary with gdbserver

I'm trying to run this armv5 binary from OWASP's mobile security guide (validate) using Android Studio's emulator on my x86_64 machine. I'm seeing very weird behaviour and would appreciate any ...
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Why is U-Boot changing this bit marked as "DO NOT CHANGE"?

While reverse engineering very early hardware initialization code of an old S3C6410 based tablet, I came across an instruction that changes a bit that the user manual (relevant info on pg. 3-50) ...
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57 views

Mach-O ARM64 using literal values instead of a frame pointer (BP) register

I'm investigating an iOS app Mach-O binary in IDA and noticed it's using a fixed constant as an offset to the SP to denote the start of the stack frame instead of a register. Is this normal? ARM ...
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124 views

What binary value does Thread and Process ID Register contains in Android ARM?

I have following instructions in Android shared library: MRC p15, 0, R3,c13,c0, 3 LDR R3, [R3,#4] MOV R0, #0 STR R0, [R3,#0xC] According to ARM documentation: Reading or writing the Thread and ...
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284 views

What is the following assembly code doing? [closed]

str fp,[sp, -4]! add fp, sp, #0 sub sp, sp, #12 str r0, [fp, #-8] str r1 [fp, #-12] L5: ldr r3, [fp, #-8] ldrb r3, [r3] cmp r3, #0 beq .L2 ldr r3, [fp, #-12] ldrb r3, [r3] cmp r3, #0 beq .L2 ldr r3, [...
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82 views

When virtual table is not the first element of structure?

Assuming that source code is compiled for ARMv7 architecure using clang (native shared object library for Android, Itanium ABI) what are the cases when virtual table pointer is not the first element ...
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785 views

Extracting firmware image from binary

I have firmware file in .bin format, but I need get firmware.img image file and Kernel uImage file for reflashing bricked device. How can I get these parts? I used Binwalk to extract content, ...
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131 views

How is `va_list` implemented in Assembler level on ARMv7 Android?

I need to extract all arguments from CallStaticObjectMethodV JNI call on ARMv7 Android at Assembler level. Can anyone advice how is va_list implemented on low level in ARMv7 Android?
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Get certain instruction count for multi-architecture binaries

I need to get an ELF binary's total count of Function call instruction conditional jump (branch) instruction The binary could be any CPU architecture, like x64, ARM, MIPS, Motorola 68K, etc. It ...
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2answers
583 views

Reverse Engineering Firmware Aether Cone

I have been trying to work out if its possible to reverse engineer the firmware for the Aether Cone. This is a good sound quality WIFI and Bluetooth speaker, but with Aether going bust, there is no ...
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141 views

Why does this command crash IDA Android native debugger?

In Android shared library that heavily protected against debugging, I found following code: CODE32 ldr pc, [pc, #-4] For me, this instruction looks like NOP; it just jumps to next instruction in ARM ...
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150 views

Debugging arbitrary ARM binary image using IDA and QEMU

i'm new to this and still learning a lot. Now i have managed to download the binary image from an Flash memory out of a unit having an OMAP5912 SoC. The SoC has an ARM9 family CPU core running little ...
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Extracting ARM Boot zImage

I'm trying to analyze the firmware of a system running Linux and connecting various home automation and security devices. Every time it boots, the GM8125 processor running ARMv5TE loads a firmware ...
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1answer
277 views

Understand what Ioctl do

I looking in ida on arm linux binary . I can see there that there is ioctl call ioctl(fd,req,num). fd is fd to /dev/module. ,req is some 4bytes and num is some number. How can I understand what ...
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131 views

Why decrement a hex value in assembly code?

I am running a disassembly of a firmware image for a Cortex-M4 and the entry point is doing something strange. EntryPoint: 00001000 db 0x00 ; '.' 00001001 db 0xff ; '.' 00001002 ...