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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How can I find out what type of processor an Intel Hex file belongs to?

I have a text file and I know that it is a firmware of a device. This file have Intel Hex Format as below: :03:8000:00:028100FA :02:8003:00:XXXXXX :02:800B:00:XXXXXX :02:8013:00:XXXXXX :01:801B:00:...
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What does the "=>" sign means in ARM assembly LDR?

what does this arm instruction means? LDRB param_1,[r12,r5]=>local_b0 In particular I don't understand the "=>local_b0" part. Ghidra decompiles it to local_b0._0_1_ = *(byte *)((int)&...
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How can i extract u-boot image from fgt90d.out firmware and install Openwrt image?

I have a lot of out of licensed Fortigate90D devices so i want to reuse and run Openwrt/pfsense on them. I have dumped and decoded the bios and got some useful datas, according to datas we can see u-...
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Why would just two bits of the SP be used here?

This is the section of disassembled code in question. It’s from a Linux kernel module compiled for 4.4.16 on ARMv7. ; Registers used: ; - r3 : unsigned long argp 0000005c mov r1, ...
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Understanding ARMv7 seemingly overly verbose disassembly

I’m working with a disassembled ARMv7 binary. There are several instances where groups of instructions seem sub-optimal, but this one really caught my attention: 00009086 movw r3, #...
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LPC2378FBD144 Arm7 hex file

I have binary file for the LPC2378FBD144 processor ineed to reverse engineer it using IDA V7.3 im little confused about memory organization values i should put in the memory organization thank you for ...
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1 vote
1 answer
268 views

Change function call to another function call in arm using IDA

Is it possible to patch arm lib in a way that changes branch instruction calling one function to another function call? I have instruction B function_a and want change it to: B function_b
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2 votes
1 answer
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Migrate x86 printer drivers to arm [Brother]

I have a Brother DCP 197C printer and I would like to print from my phone using a raspberry pi. To archieve it I need to install drivers, but brother only provide x86 and x64 drivers, any way to do it?...
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Reverse an encryption algorithem in APK .so file

I try to reverse a cipher algorithm (I guess Tiny Encryption Algorithm (TEA)) in an android application. But I have a serious problem in initializing arguments. How I can understand that I have ...
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2 votes
1 answer
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What do these 2 Ghidra warnings mean?

When disassembling ARM binaries in Ghidra, I often see these warnings: /* WARNING: Could not recover jumptable at 0x0747c198. Too many branches */ /* WARNING: Treating ...
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What is the meaning of ARM LDAXR/STLXR instructions?

Often while disassembling ARM files, I see some code snippet with the following pattern: loc_BB30: .text:C0 FE 5F 88 LDAXR WZR, W0, [X22] .text:00 04 00 51 SUB W0, W0, #1 .text:...
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Setting Breakpoints on Thumb Instructions in GDB

I'm practicing reversing a stripped arm binary, and found that when I set a breakpoint at say 0x010451, and run the program, gdb spins forever until I hit ctrl+c. When I do, the current pc is at the ...
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Emulator that emulates arm hardware

I want to hook arm instructions as they executes but most of the emulators are based on VirtualBox that uses houdini to translate arm instructions to x86, and i really can't hook a native JNI lib, ...
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2 answers
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How to determine ARM architecture from the ELF file extracted from the firmware?

I have extracted the ELF file from the flash dump of a printer, I cannot find too much information about the SoC chip on the printer. What's the best practice to determine the ARM architecture (ARMv7-...
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1 vote
1 answer
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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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2 votes
1 answer
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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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1 answer
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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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1 vote
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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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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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1 answer
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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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1 vote
0 answers
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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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1 vote
1 answer
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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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1 vote
1 answer
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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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5 votes
1 answer
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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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1 vote
1 answer
113 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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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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8 votes
1 answer
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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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2 votes
1 answer
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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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1 vote
0 answers
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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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1 vote
1 answer
610 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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1 vote
2 answers
745 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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0 votes
1 answer
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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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1 vote
0 answers
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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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1 vote
1 answer
580 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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2 votes
2 answers
207 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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1 vote
2 answers
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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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1 vote
3 answers
1k 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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-1 votes
2 answers
1k views

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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10 votes
3 answers
8k views

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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2 votes
0 answers
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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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1 answer
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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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2 votes
1 answer
2k 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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0 votes
1 answer
427 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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2 votes
1 answer
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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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1 vote
0 answers
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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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1 vote
1 answer
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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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1 answer
623 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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