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Questions tagged [assembly]

A family of very low-level programming languages, just above machine code, where each statement corresponds to a single machine code instruction.

8
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3answers
1k views

Trying to reverse engineer C code that is 64bit assembly

This is the code I am looking at 0x0000000000401048 <+70>: mov 0x401ba0(,%rax,4),%eax This is an array of 15 integers. Just wondering how I can access indices 0 to 15 in gdb Thanks
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votes
2answers
3k views

Why are special tools required to ascertain the differences between two related binary code files?

How comes that text diffing tools like diff, kdiff3 or even more complex ones usually fail at highlighting the differences between two disassemblies in textual form - in particular two related binary ...
34
votes
5answers
4k views

What is the reason for this method to call itself?

While reversing a 32bit Mach-O binary with Hopper, I noticed this peculiar method. The instruction on 0x0000e506 seems to be calling an address right below the instruction. What would be the reason ...
18
votes
2answers
3k views

Anti-debug techniques on Unix platforms?

I am trying to scan all possible techniques to disrupt the usage of a debugger on a Unix platform (ie POSIX and a bit more). I am thinking about techniques such as the PTRACE test at the beginning of ...
34
votes
7answers
10k views

What hints in machine code can point me to the compiler which was used to generate it?

When I am looking at the machine code of an application, are there hints and patterns I can discern from the generated machine code which would indicate which compiler (and possibly version) was used ...
21
votes
7answers
3k views

How are x86 CPU instructions encoded?

I'm writing a small utility library for hooking functions at run time. I need to find out the length of the first few instructions because I don't want to assume anything or require the developer to ...
20
votes
7answers
5k views

How is a structure located within a disassembled program?

I took a basic 40-hr Reverse Engineering course a few summers ago. While teaching us to use IDAPro, the instructor demonstrated, rather quickly and without explaining much, how to label certain ...