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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30 views
Making changes to a binary file that is a Intel hex file?
im trying to reverse the SMOK Alien firmware which can be found here. The file is a Intel HEX file. I then used srec_cat on it to create a binary file which i can actually open in an editor in order ...
3
votes
1answer
149 views
Need help understanding XOR cipher
I am trying to modify a save file for a game. I think it is using an XOR cipher to encrypt it. Looking though the disassembly I think I found the function that decrypts it. I ran the assembly ...
2
votes
1answer
54 views
ELF - The start address of .got section is different from the entry point address of the GOT(global offset table)
I used readelf to read the information of the ELF file. I found the address of .got section in the section header is different from the GOT entry point address read from the dynamic section. Is the ...
1
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2answers
118 views
Reverse engineer a ARM-v7a function
Currently I am trying to reverse engineer the following armeabi-v7a function:
I already wrote the following Java code:
static double getFunc(double param0, double param1, double param2, double ...
4
votes
2answers
84 views
Disassemble ELF - PC is set to 0?
I tried to disassemble a ELF file which is a shared object file executed on armv7a (Android). I saw a strange block. It seems that the PC, program counter register, is set to 0. Did I miss something ...
1
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1answer
73 views
Finding RegisterNatives function calls in JNI_OnLoad's assembly code
My goal is to see what a native method m does. It doesn't have a direct counterpart in the so file, but I've found the JNI_OnLoad function's ARM assembly code. It starts with
AAAAAAAA <JNI_OnLoad@@...
0
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1answer
98 views
How to Modify this Branch in ARM64?
I try to modify the branch of this disassembly in a binary:
SUB SP, SP, #0x60
STP X26, X25, [SP,#0x50+var_40]
STP X24, X23, [SP,#0x50+var_30]
STP X22, ...
1
vote
1answer
59 views
Could someone explain how this ARM instructions works compared to the actual Objective-C code?
I'm trying to understands how it works by decompiling my own Objective-C code. Here's the decompiled instruction:
var_8= -8
var_4= -4
SUB SP, SP, #8
MOVS R2, #1
STR ...
1
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0answers
94 views
Patching an ipa (iPhone app) using Hopper Disassembler
I have learned in the past to patch some iOS apps to bypass jailbreak detection. Today, I decided to change the UI elements in the Spotify app on iOS Platform (ios 11). I downloaded a .ipa file of ...
-1
votes
1answer
41 views
Which ARM command is influencing the SP position?
I do static analysis of ARM assembly code (I can't debug it).
When I look on argument that in SP+0x<SomeOffset> I can find what I'm looking for, but if I look a few lines further down I see ...
1
vote
1answer
24 views
Why would an ELF SHT_REL section contain relocations outside the section its sh_info refers to?
I have a .so from an Android JNI/NDK application. Here are two of its sections:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[10] .rel.plt REL ...
2
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2answers
196 views
How can I make sense of an Android NDK library?
So I'm currently trying to understand how an Android app interprets the data sent from a Bluetooth-enabled scale.
Understanding the Java code was relatively easy. The code was obfuscated but I found ...
6
votes
1answer
333 views
Why is this ARM binary throwing an 'Illegal instruction' error and quitting?
Issue
I'm hoping someone can help me determine why this binary won't execute.
It is a closed-source, stripped ARM binary. That said, it is freely downloadable on the internet so there is a link to ...
3
votes
1answer
53 views
ARM Thumb2 register usage
I am reversing ARM Thumb2 code.
I am looking for a table that shows which registers are used to pass arguments to functions, and which registers must be saved after the function ends.
By the way, if ...
10
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1answer
278 views
How to write [sp+local_variable] in radare2
Hello I'm playing with my native android library, everything was going smoothly till now. I have problem with opcodes, i don't know how to tell radare2 to write str opcode with specifc registry, and ...
0
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1answer
94 views
how to understand branch arm instruction
I have this instruction F6F700B8 I know that it b #-0xA000 but how I can understand from F6F700B8 that is b #-0xA000 ? .
When I tried to translate it on http://armconverter.com/hextoarm/ I get B.W #...
6
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2answers
208 views
Best Way to Identify Statically Linked Functions in Firmware
I have a piece of firmware that I pulled off an NXP LPC17XX series chip. Through reviewing the processor manual, I was able to identify the entry point of the code and disassemble the code without any ...
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1answer
39 views
Ldr arm thumb2 must be multiple of 4?
I saw here http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/CIHDGFEG.html that on arm thumb2 ldr must be multiple of 4.
I run on arm thumb 2 and want run this instruction ldr r0, ...
-1
votes
2answers
161 views
translate arm instructions to hex
I looking for simple tool(not site) to translate arm instruction to hex like http://armconverter.com/.
Without linker , I want put 1 instruction , and want get the hex .
Do you know one please?
1
vote
1answer
132 views
Determining endianness of PE files (Windows on ARM?)
For ELF files, there is a field near the start of the ELF header that indicates the endianness of the file:e_ident[EI_DATA]. If an application wants to extract data from the header of a given ELF ...
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1answer
63 views
Arm function save registers r0 and r1
I see arm 32 bits assembly code.
Usually each function do push { r4-r9,lr} ( save 6 registers on stack ). And in the end of function pop them .
I see function that save push {r0,r1,r4-r9,lr} but ...
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2answers
33 views
Edit arm thumb2 intelhex file
I have intelhex file to arm 32 bits thumb 2.
I want edit this file add/ change instructions.
Looking for easy and free tool (prefer gui windows tool ) to do it please.
0
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1answer
169 views
How ida choose arm Thumb/Thumb2
I load binary file to ida and choose arm cpu.
How can I see if ida choose on arm/arm Thumb2 / arm Thumb? and how can I change it?
Bytes translate is depend witch arm is it(arm/arm Thumb2 / arm ...
2
votes
2answers
117 views
Arm ldr diffrent between # and =
In ARM assembly, what is the difference between
ldr r4, =0x44454433
and
ldr r4, #0x44454433 ?
0
votes
1answer
139 views
Patching branch on assembly code
I compile this code
1. #include <stdio.h>
2. void F(int a, int b)
3. {
4. int c= a+b;
5. int d= a*b;
6. }
7. void printAll()
8. {
9. printf("test1");
10. printf("test2");
11. ...
0
votes
2answers
126 views
explain c compile code
I compile c code to arm with this site https://godbolt.org/
int F(int a, int b)
{
int c=0;
for(int i=0;i<=10;i++)
{
c+=a+b;
}
return c;
}
the result was
F(int, ...
0
votes
1answer
99 views
Newbie here: hidden values in assembly? [closed]
So i'm new to the whole reverse engineering thing with only experience in C#. So I wanted to try and change the framerate of applications (eg. this unity game) at an assembly level on iOS ( I have an ...
0
votes
3answers
593 views
What is an immediate value?
I just read this post.
What does mean an "immediate value" ? Is there any string/ascii there?
How can I find this value on the binary file?
I have the same code and when I search on 0x28 address I ...
0
votes
2answers
545 views
How does the ldr instruction work on ARM?
ldr r0, #0x28
What does thw ldr instruction ? Does it load a string from some offset?
How can I find the string/value that is actually loaded ?
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vote
1answer
105 views
Undefined instruction in Go binary compiled for ARM
I'm reverse engineering an ARM binary written in Go, and the following code sequence occurs fairly often (from runtime.cgoIsGoPointer):
BL runtime.panicindex
DCD 0xF7FABCFD
or, from runtime....
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vote
1answer
227 views
Binary encryption
I'd like to ask your help to understand the algorithm used to encrypt these hex/bin firmware (for an ARM-Cortex M4 microcontroller).
In the tar file above you can find different firmware versions.
...
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0answers
371 views
Arm hex firmware reverse
it has been a couple of months that I'm working on the firmware produced by a company that makes (not licensed) gamepad console adapters.
One of my goal was to understand how they bypassed (hacked) ...
1
vote
1answer
97 views
How to change a string in a arm 32bit lsb executable binary using radare2?
I have a arm 32bit lsb executable which prints "hello world" to the screen. How do I change the string to "Good bye" using radare2.
I believe this will teach me the basics of RE and radare2.
Thank ...
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2answers
256 views
How can i start the RE process in radare2?(make changes to the registers) [closed]
I'm an absolute newbie to reverse engineering. I have a 32bit lsb arm binary which I would like to reverse engineer using radare2. How should I begin ?
2
votes
1answer
186 views
Hex-Rays function signature does not match demangled name
From the demangled name, I know that a function takes an std::string const& as a parameter but when generating psuedo-c code with Hex-Rays' decompiler it autodetects the parameters as (int a1, int ...
1
vote
1answer
76 views
ARM function start points look strange sometimes in IDA Pro
I am a little bit confused with this strange issue with ARM firmware. My original firmware file has no symbols, so I need to find them by myself trough the internet. But here I have a certain function ...
0
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0answers
170 views
ELF hook function by address
I used this to intercept (https://github.com/asLody/ElfHook). Everything is simple enough, but here's the question. Let's say I want to intercept a function, not by its name, by its address, as in the ...
3
votes
1answer
759 views
Entry point for STM32 firmware
I'm trying to disassemble a firmware for a DIY project, open hardware but closed firmware.
My question is how to initialize the disassembler properly (Hopper Disassembler).
The values I try to figure ...
2
votes
1answer
82 views
ARM system crashes after changing stack address
-- Edit with latest update on the problem, it is not solved yet :( --
While playing with an ARM embedded Linux system (Version 3.8.13), out of curiosity, I created a small "debug" kernel module.
...
3
votes
2answers
552 views
ARM64 syscalls table
I wonder if there some syscall table for Linux ARM64 architecture?
I found syscall table for Linux ARM32 and many other architectures, but the problem still exists.
Does anyone know where can I find ...
1
vote
1answer
1k views
Inject code into JNI function (Android shared library)
An android app loads a native library (.so) using System.loadLibrary. It then calls a specific function, which takes 3 input variables, and returns a string containing a MD5 hash.
You can see the ...
0
votes
1answer
262 views
DCD data in IDA disassmbed file
There is some DCD data in a disassembled binary using IDA as shown the image description. The binary is an ELF of ARM processor type. I want to know what are these data? Is it possible they be code ...
0
votes
1answer
236 views
ARM ELF Obfuscation [closed]
Metamorphic is a technique to obfuscate a binary and change the opcode sequence and create new samples with same functionality. In my case, I have some elf binary of ARM processor type and their ...
0
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0answers
51 views
Set offset to zero using 4 bytes with ARM/Thumb Instructions
I have come to the conclusion, with my limited knowledge, that this is not possible. I am asking here as there may be a solution.
I would like to achieve setting [R0, #0xC0] to #0 with just 4 bytes. ...
4
votes
2answers
339 views
HexRays: Variadic methods like printf
I have identified a routine that behaves exactly like printf in an ARM64 binary. Arguments are passed in the standard fashion (e.g. X0, X1, X2 ...) and I have given the function the signature (Y) of:
...
4
votes
1answer
102 views
ARMCC/C++ Empty Vtable entries
I am reversing an application for the 3ds which are compiled with ARMCC.
I found the vtables of the key classes and have a problem figuring out how the C++ representation of these was.
Vtable of ...
1
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0answers
81 views
Why does IDA mark this as end of function?
I'm analyzing a .so file that is a part of an android application.
I've stumbled upon this block of code:
LOAD:0001B63C sub_1B63C ; CODE XREF: sub_1B628+Cp
LOAD:...
0
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0answers
42 views
Function Call to function not in file?
Trying to reverse engineer an ARMv7 ELF file. There seems to be a function, that populates a ptr, but, the function does not seem to be located within the file. I know the ptr is in fact populated, ...
0
votes
0answers
147 views
Problem debugging with IDA and QEMU
I am trying to debug an ARM ELF file using IDA Pro and QEMU.
No matter what address I choose to start debugging at, the first instruction is replaced with the instruction SVCMI 0xF0E92D, trying to ...
0
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1answer
100 views
Help with LDRD Instruction
According to documentation, the LDRD instruction works, as follows
LDRD R8, R9, [R3, #0x20]; load r8 from a word 32 bytes above the address in R3, and load r9 from a word 36 bytes above the ...
