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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Confusion between different ARM architectures

I am trying to develop a machine learning model to help with the process of reverse engineering. As the first stage, we are currently trying to train an embedding model that understand the ...
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ARM multiply compiler optimization

I need help interpreting this compiler optimization: ;R12 = 0x88888889; UMULL LR, R2, R12, R3 ; R3 * 0x88888889; MOV R2, R2,LSR#3 ; ((R3 * 0x88888889 << 32) >&...
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JTAG TCK on Intel X Scale (ArmV5) PXA270

Is TCK on JTAG the same speed as CPU clock on a Intel X Scale (ArmV5) PXA270? I'm probing signals on pads around the CPU and got a waveform like: But I don't know whether any of this data is JTAG, or ...
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print instructions app executes using frida android

i connected my android device over tcp and now i want my device to print all instructions as the app executes when it loads this module but print instructions from current thread not those present in ...
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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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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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47 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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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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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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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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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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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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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
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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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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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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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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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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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Using Gdb-Server with Ida 7.4 failed

I have gdb-server to arm , downloded from https://github.com/therealsaumil/static-arm-bins/blob/master/gdbserver-armel-static-8.0.1. When I use Ida 6.6 to connect remotly to this gdb-server that work ...
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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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60 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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Identify encrypt /decrypt rsa function

I have arm static binary that I know it use RSA. How can I find the encrypt/decrypt function?
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Find common functions in arm static binary

According to Detecting libc function with IDA I have static binary for arm and I want to find common function like fread sleep printf ioctl etc. When I looking for string in this binary I found glibc ...
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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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a.out: Invalid ELF image for this architecture

I am trying to run arm executable using qemu and I am getting this following error a.out: Invalid ELF image for this architecture. My assemble code hello.s .text .global _start _start: mov r0, #1 ...
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Loading garmin Foretrex 601 firmware into IDA Pro

I'm trying to load a Foretrex 601 firmware into IDA pro (fw_all.bin) But I have no idea how to do so since is a ARM architecture and it not drag&drop like x86/x86 arch. The GCD file can be ...
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211 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
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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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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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226 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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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
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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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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
43 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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118 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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120 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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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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Building firmware.bin from mtd partitions

Working on reversing current router firmware here and I can't find any sources from the manufacturer for their firmware and toolchain. I wanted to do this approach. firmware.bin is loaded and ...
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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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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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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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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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