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Questions tagged [machine-code]

Machine code is the lowest level form of encoding instructions (binary). It is usually what the processor directly decodes and executes.

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How to increment and decrement machine code in radare2?

I watched a video (I believe it was a talk by the author of radare2) of how to increment machine code in radare2 very easily, simply by hitting 'c' and then using + and - to respectively increment and ...
2
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2answers
509 views

Can Machine Learning be used to develop better reverse engineering tools? [duplicate]

So i googled this but other than some papers i couldnt find any reverse engineering tool that was built using machine learning I'm not an expert in machine learning and deep learning but it seems ...
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2answers
310 views

How identify witch cpu run assembly [duplicate]

I have around 300 bytes of binary machine code. I don't know which instruction set the code is for so I can't open it with IDA. Is there any tool that can help identify the instruction set?
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537 views

how data types and variables are converted to machine code?

I know that every x86 instruction has an opcode for that, but I don't know how data types and variables are converted to machine code. So I tried to figure out. I wrote a simple C program and ...
2
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3answers
740 views

Building a control flow graph from machine code

I want to write my own soft, that can disassemble code, and turn it into conrol flow graph. Now i know the basics of graph theory, but i don't get where i should start, do i need to basically keep the ...
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3answers
3k views

Determind length of instructions in bytes

Where is it possible to find a list of x86 instructions (and x64 instructions) with the (hex) opcode and the length/size in bytes of the instructions, such as: 0x90 = NOP = 1 byte 0xE9 = JMP = 5 ...
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1answer
237 views

Which architecture is this machine code?

I dumped a ROM recently. I tried to disassembled the machine code* for many architectures, but I always got assembly which, at best, looked like garbage. Note: I can perfectly read the strings the ...
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2answers
332 views

How to identify code ran when clicking on an object in a game

I've played with using software like cheat engine to modify memory, null out code and even inject some code of my own. However finding the right spot to modify is always a difficulty. I'd like to be ...
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2answers
527 views

Difficulty of reverse engineering based on target

I'm not asking about the difficulty of reverse engineering in general, but rather the difficulty of reverse engineering a particular hypothetical target. We'll assume that having the source code ...
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2answers
281 views

One-pass streaming algorithm for detecting bytecode/opcode?

I am searching for an algorithm and/or snippet of code that provides a one-pass algorithm over a steady datastream that can detect a valid sequence of bytecode or opcode. There are no PE32, ELF, or ...
1
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1answer
640 views

Code-Cave Assembly Patching Issue in x64_dbg

I'm trying a code-cave approach to this query that was asked about on this forum earlier. I'm using x64_dbg to perform this task. My issue here is that after I have written the extra lines of ...
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0answers
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Decoding A/C IR Codes

I captured infrared codes from an air conditioner remote to realize each code contains the entire state (i.e. temperature, mode, fan speed, etc.) every time a button is pressed. I believe this is so ...
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2answers
295 views

Reverse engineering and programming byte-by-byte on mobile OSs?

I can't find any disassembling programs for the various binary formats out there that can run on OSes like Android, iOS, Blackberry, etc. These are the only devices I have access to, and I am trying ...
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2answers
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how can the processor instruction set be identified solely by examining a binary image? [duplicate]

Constraints: I am doing reverse engineering of a binary firmware image of unknown provenance, which operates on a device that is not physically accessible to me. That is, I can't take apart the ...
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3answers
139 views

Any programs that can convert textual ones and zeroes to full comparison bytes?

since the byte is the lowest addressable datum and bit rotating/flipping can come in to play here, are there any programs that can enable you to write ones and zeroes (binary), and after every 8 of ...
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0answers
90 views

How to write bit-by-bit to a medium, as opposed to byte-by-byte? [closed]

I am trying to write binary opcodes, but I can't in a text editor as 1s and 0s because: 1 or 0 on a text editor ends up being stored as the literal ASCII equivalent code on the storage medium, not ...
6
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1answer
864 views

I need quick correction on this x86 opcode conundrum

I am trying to figure out how to encode the instruction MOV DS, AX, but I am confused from the opcode table as follows: Is MOV DS all one byte, or is MOV one byte, DS the second, and the AX the third?...
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2answers
300 views

Issues writing a bootloader in x86 16-bit machine code

I am having trouble displaying simple text. I am trying to do it all in machine code with INT 10h, but: I can't find the binary opcode for INT 10h anywhere in the Intel Manual. I can't figure out how ...
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1answer
162 views

Is there always 1:1 correlation between hexadecimal and binary?

I was wondering this because I have found that some instructions, on the machine code level, are too large if taken a step down from hex to 0s and 1s. On Motorola 68000 I found that some instructions ...
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2answers
1k views

Can anyone here show me the binary opcodes for these x86 assembly instructions? [closed]

I want the exact binary opcodes executable to CPU directly. [BITS 16] ; 16 bit code generation [ORG 0x7C00] ; Origin location ; Main program main: ; Label for the start of the main ...
7
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1answer
214 views

How to view the instruction pipeline?

Instruction pipelining is used to execute instructions in a parallel fashion by dividing them into several steps .When I pause the execution in a debugger I am only able to see the location of the eip ...
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1answer
1k views

Common Lisp bytecode or machine code decompiler

Does anyone know of a decompiler for Common Lisp? I know most lisp environments include a disassembler. But I don't know of any decompilers. I would think it should be possible to make a decompiler ...