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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STM32 and Ghidra: REing an ARM Cortex (Thumb) firmware doesn't get the entry-point right

I'm reverse engineering a firmware used on an STM32 microcontroler. With the datasheet and some help I managed to find the entry point (Reset vector): MasterStackPointer ...
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2 answers
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ARM (STM32) memory mapping on Ghidra: offset only part of the firmware file

I have a binary firmware that I'm trying to reverse engineer. I loaded it up on Ghidra, setting the file as raw binary, ARM Cortex, little endian. I used an address offset of zero for the file. And I ...
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Ghidra: Ignoring partial resolution of indirect

The decompiled code for a function shows "Warning: Ignoring partial resolution of indirect" and I am not able to determine the values of variables local_18 in this decompile: uint ...
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Cutter cannot parse AUTDA instruction

I work on reverse engineering of an iOS software using Cutter, and receive several opcodes as "invalid". For example: <addr> 301ac1da invalid Looking up the hex ...
1 vote
1 answer
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Trying to reverse a bin file

I'm trying to reverser a bin file with Ghidra, without success for the moment, I can't find any functions in the decompiled file. he bin file is for an ARM 32bits, I'm pretty sure this is an stm32, so ...
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Can an OpenWrt FIT kernel be virtualized in qemu?

I have a router I'd like to virtualize in order to do some dynamic analysis. I could virtualize individual binaries with qemu, but I'd like to have the whole ecosystem up and running. I'll start here: ...
2 votes
1 answer
67 views

Is there any way to understand if a raw binary firmware is Cortex-M or not?

I have a list of firmwares, and I should filter just the Cortex-M type. Is there any automated way that I can distinguish them from other ARM firmwares? I have some ideas like Interrupt vector Table (...
0 votes
1 answer
81 views

Reverse engineering ELF: The e_phentsize field in the ELF header is less than the size of an ELF program header

I have extracted the .so binary libTheArmKing.so (located in lib directory in apk file) from a hack of World War Heroes game (an Android game) from Plantimod Forum. file output: libTheArmKing.so: ELF ...
6 votes
4 answers
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Do I have to learn computer architecture for underestanding or doing reverse engineering?

I am completely noob in reverse engineering, and I've just started to learn it. Now I have this question in my mind, that does a reverse engineer use any computer architecture knowledge for doing his/...
3 votes
1 answer
185 views

STM32 - Disable Voltage Check

I'm planning to edit the binary Firmware for an STM32F030K6T6 ARM microcontroller used in the IKEA Fyrtur blinds. In particular I'm trying to disable the Voltage check (allow alternative power source)...
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Patching a B(ranch) causes segfault in ARMv7 binary, while the same patch (with JMP) works on x64 binary

Any ideas why trying to patch a ARMv7 binary causes a segfault while basically the same patch on the Win64 version of the software works as expected? Here is the Win64 version, that works UPX0:...
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Gdb hardware watchpoint error on android

After failing to find a solution to this I have started using Gdb and have encountered another error. Gdbfails to set hardware watchpoint when I'm remote debugging a rooted arm7-a target. It supports ...
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2 votes
1 answer
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LLDB debugging on android?

I currently don't have a pc. I have two rooted devices Arm64 host device with Debian rootfs and the device to be debugged which contains the lldb-server binary armv7. I am trying to remote debug my ...
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5 votes
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What's the format of Mediatek MRE VXP file and how to create a workable VXP binary?

Background Mediatek's MRE (MAUI Runtime Environment) is the default runtime on Nokia S30+ platform, replacing the J2ME platform on older Nokia. From MRE's page: MRE (MAUI Runtime Environment) is a ...
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not called functions

trying to reverse a Cortex-M0 bin file using Ghidra. There are functions that are Never Called any where in the code! (but actually should be called somewhere !) What could be the reasons? Tnx
1 vote
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IDA show xrefs in .pdata and nothing else

I'm debugging the Windows ARM64 version's EFI (bootaa64.efi). Using QEMU and GDB I was able to find that bootaa64.efi was stuck in one of the two functions BlKernelSp0SystemErrorHandler and ...
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1 answer
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ARM - Understanding a "base address" when reversing firmware

I've read that when reversing firmware from an embedded system it's important to get the right base address of the firmware to make sure cross references to things such as strings work when looking at ...
1 vote
1 answer
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Need help identifying this SoC

Does anybody know the manufacturer of this ARM CPU / SoC? I cannot find any information about it. I don't even know what the character in front of “Star” means. “SAV500D” seems to be the model, the ...
2 votes
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Is it possible to dump firmware of a device via USB port?

I have a device which can be connected via USB port. The vendor of this device provides a tool for upgrading firmware of this device via USB port. lsusb command says that this device has following ...
1 vote
1 answer
80 views

ARM/THUMB assembly mismatch between binaries causes crash

I am trying to play around with an app for Android and every time I try to call a function (lua_gettop() from the Lua 5.1 library) from the app's address space, it hits me with ILL_ILLOPC. I made sure ...
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How to resolve illegal instruction for this ARM stack exploitation?

Summary I am trying to write a stack overflow exploit for ARM Cortex-A72 running Raspberry Pi OS (32-bit). Because of my choice of OS, I am restricted to the ARMv7 (32-bit) instruction set. I have ...
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ADDS(operations with S suffix) -Arm

This question was asked before here but in the answers I did get what i was looking for. Consider this: ADDS R0 RO R1 As far as I know to update the cpsr flags a subtraction has to be made. So after ...
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android index.android.bundle file

I downloaded an app from Raccoon. I got these files: com.company.name-3423.apk config.ar-3423.apk config.armeabi_v7a-3423.apk config.en-3423.apk config.iw-3423.apk config.ru-3423.apk config.xhdpi-3423....
1 vote
1 answer
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Hopper Disassembler AArch64 assemble instruction syntax error

As the screenshot shown above, I attempt to change cbz to cbnz, hopper gives me "syntax error". At this moment I can only change it by editing the instruction encoding in hex view as a ...
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1 answer
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Change iOS app binary file

I want to manipulate iOS binary file and change two strings in it. I used hex editor to search and change these strings. But after the binary file is uploaded and replaced with the origin app's binary ...
2 votes
1 answer
372 views

Arm custom u-boot reversing

I'm trying to reverse a custom u-boot that implements cryptography for the Kernel at runtime (the Kernel at rest is encrypted also in a flash). I can probably ask the IoT vendor to provide the ...
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Reading from buffer and printing output to a text file

00001f10 2846 mov r0, r5 00001f12 6349 ldr r1, [pc, #0x18c] {data_20a0} 00001f14 7944 add r1, pc {data_ce5e, "OK:%16[^:]:%16[^:]:%d:%d:%d:%d:%…"} ...
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Code caves in arm assembly

In a disassembled elf binary i found these arm thumb instructions: function0 0x002cc3a8 8079 ldrb r0, [r0, #6] 0x002cc3aa 7047 bx lr In the codecave these were the initial hex ...
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Branching in arm assembly

This is an example assembly code: function0() 0x0.mov r0, #1 0x8.mov r1, #20 0x10.mov r2, #6 0x18.cmp r1, #16 0x20.b function1 function1() 0x28.cmp r0, #1 0x30.b functionX functionX(...
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1 vote
1 answer
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How to insert arm instructions into a function in a native library?

I am new and am still learning assembly languuage. In a native android app library that has been disassembled i found this function which had 1 instruction. addres hex arm instruction ...
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2 votes
1 answer
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When would a program normally transfer data between memory and coprocessor?

In the analysis of an ARM binary, when would one normally encounter transfer operations between memory and a coprocessor? These are encoded as the LDC and STC operators. Would it be common for ...
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ARM floating point register S0 used without initialization

The following code snippet is the first few assembly instructions of a function. The code runs on armv8a. SUB SP, SP, #0x170 is the first assembly instruction of the function. Please note the ...
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Running ELF file built for ARM arhitecture

My goal is to run and debug ELF file (c444) which is compiled for the ARM architecture. I have some experience with x32 and x64 Intel architectures. However, I down know how to proceed with ARM-based ...
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2 answers
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How to calculate the value needed to branch two points in IDA pro?

I need to find how to get the value to make a branch between two points in IDA Pro, but I can’t figure it out. For more context: the instructions I’m following says “Calculate the value needed to do a ...
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1 answer
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What does this function do?

I'm trying to understand what client sends to server. I already did most of the work, but one function left. I can't understand what to do with this function and what it does. I've tried to change ...
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1 answer
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Why the disassembled code in IDA is different from in xcode? And How to solve unk_xxxx in IDA View?

I have built an executable file (the architecture is ARMv7, the base SDK is iOS), which depended on an xxx.a file in xcode; I don't have the source code of thexxx.a. I want to check some logic in `xx. ...
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1 answer
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Where stack canary is located?

Is stack canary located between the local variable in stack and the place that the function saved the registers in the beginning of function? push r5,lr so I can't change any registers (while the ...
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2 votes
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Finding (or building) a kernel for Huawei EchoLife EG8145V5

I have a Huawei EchoLife EG8145V5 for which I am trying to build some software. It has a built-in Linux distro of some sort, but I would like to add to it, as there is "plenty" of storage ...
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2 votes
1 answer
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How to know when a subroutine starts when reversing an ARM64 file?

I'm kinda new in the ARM world, and a question suddenly came up in my mind: how does (your favorite reverse engineering tool) know where a subroutine of an ARM64 file is starting (because I'd like to ...
3 votes
2 answers
883 views

Disassembling ARM based Camera Firmware

I'm trying to disassemble hikvision firmware 5.5.85. I want to extract the contents of digicap.dav file. Binwalk is unable to extract the known zip files. binwalk -e digicap.dav DECIMAL ...
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1 vote
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Debug bFLT in qemu-arm-static

I have bFLT binary (into linux-arm arch.) that I can run with qemu-arm-static . I want to debug that binary dynamically with GDB. I know I can debug binary with qemu like qemu-arm-static -g 1111 <...
1 vote
1 answer
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Ghidra showing pointer being given as size argument of calloc

I'm attempting to figure out the structure of a "God object". I found where it's being initialized, but I've never seen calloc used like this before: god = (God *)calloc(1,(size_t)&...
2 votes
0 answers
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Understanding Hex-Rays syntax

I have a Ida decompiled function that invokes another function through a function pointer but I'm really confused how it calculates it's address. I'm new to hex-rays syntax. int __fastcall SUB_XXXX(...
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ARM Cortex-M0 - How to either (non-intrusively) extract firmware or modify downloadable firmware (NuMicro NUC126)

As a hands-on introduction into RE, I've decided to take on a small, simple embedded device. In hindsight, it was probably a mistake. This "project" has consumed me for about 2 weeks. ...
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2 votes
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Reversing uboot on an aarch64 Hi3559AV target problems

I am trying to reverse uboot for an ARM aarch64 Hi3559AV target. I've dumped the binary uboot.bin.gz, and have loaded it in IDA at the correct address. IDA seems to see a lot of strings (and ...
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3 votes
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Find the entry point in Interrupt Vector Table ARM9

I'm analyzing the firmware of a device that has the cpu ARM946E-S. It has not a file system, just assembly code and strings. I've disassembled the firmware using ida pro, but I couldn't find the entry ...
3 votes
2 answers
287 views

What does this ARM assembly code do?

I'm trying to figure out the password that is used to access the U-Boot shell, as mentoined in my previous question. I'm having trouble understanding how exactly the code works. Here is an image of ...
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Loading a U-Boot ARM flash image into IDA Pro

I have a U-Boot image file which was extracted from flash memory of a board with an Hi3520D ARM CPU. I would like to load this file into IDA Pro and dig out the password that is required for accessing ...
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1 vote
1 answer
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IDApython - Turning a modified operand into a string reference

I am working on an IDAPython script that is supposed to fix the disassembly of a firmware, by resolving it's symbol table. The core of the script is working fine, but I have some issue when it comes ...
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Reverse Engineering Classes in ARM

I came across this part in the book Reverse Engineering For Beginners book by Denis Yurichev. It writes about reverse engineering Classes in C++, but it doesn't provide any examples in ARM. Page 546 ...
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