This C/ASM project is about the principle of self-reproduction and the problems that derive from it. It is a perfect introduction to more complex projects, particularly malware projects.
A quine is a computer program (a kind of metaprogram) whose output and source code are identical. As a challenge or for fun, some programmers try to write the shortest quine in a given programming language.
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The first executable is named
Colleen.
The source code contains:
◦ A main function.
◦ Two different comments.
◦ One of the comments is present in the main function
◦ One of the comments is present outside of the program.
◦ Another function in addition to the main function. -
The second executable is named
Grace.
• When executed, the program writes in a file namedGrace_kid.c/Grace_kid.sthe source code of the file used to compile the program.
• The source code contains:
◦ No main declared.
◦ Three defines.
◦ One comment.
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printf in ASM: When not using floating point registers, al needs to be zeroed out before printf is called, otherwise it will segfault.
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The first six integer or pointer arguments are passed in registers as follows:
- rdi: Used for the first integer or pointer argument.
- rsi: Used for the second integer or pointer argument.
- rdx: Used for the third integer or pointer argument.
- rcx: Used for the fourth integer or pointer argument.
- r8: Used for the fifth integer or pointer argument.
- r9: Used for the sixth integer or pointer argument.
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Combining the flags: O_RDWR | O_CREAT | O_TRUNC = 02o | 0100o | 01000o = 01102o (octal) O_RDWR (2) + O_CREAT (64) + O_TRUNC (512) = 578 (decimal)
// To stop vim from adding a newline at end of file,
// add these two lines in .vimrc
:set nofixeol
:set nofixendofline
// Remove new line character at the end of a file
vim -b <file>
// once in vim:
:set noeol
:wq
// Find out the section where the string data is stored
hexdump -C Colleen
// View the details of the .text section of an ELF file
objdump -h -j .text <ELF_file>