[mipsel] execve 분석

2014.12.26 20:24

소스

#include <stdio.h>


int main ()

{

char *name[2];

name[0]="/bin/sh";

name[1]=0;

execve(name[0], name, NULL);

}



메모리맵

(gdb) shell cat /proc/2484/maps 

00400000-00401000 r-xp 00000000 08:01 529142     /home/mk_shellcode/execve

00410000-00411000 rw-p 00000000 08:01 529142     /home/mk_shellcode/execve

77e3a000-77fa7000 r-xp 00000000 08:01 265575     /lib/mipsel-linux-gnu/libc-2.13.so

77fa7000-77fb6000 ---p 0016d000 08:01 265575     /lib/mipsel-linux-gnu/libc-2.13.so

77fb6000-77fbf000 r--p 0016c000 08:01 265575     /lib/mipsel-linux-gnu/libc-2.13.so

77fbf000-77fc1000 rw-p 00175000 08:01 265575     /lib/mipsel-linux-gnu/libc-2.13.so

77fc1000-77fc4000 rw-p 00000000 00:00 0 

77fc4000-77fe7000 r-xp 00000000 08:01 265572     /lib/mipsel-linux-gnu/ld-2.13.so

77fef000-77ff1000 rw-p 00000000 00:00 0 

77ff5000-77ff6000 rw-p 00000000 00:00 0 

77ff6000-77ff7000 r--p 00022000 08:01 265572     /lib/mipsel-linux-gnu/ld-2.13.so

77ff7000-77ff8000 rw-p 00023000 08:01 265572     /lib/mipsel-linux-gnu/ld-2.13.so

7ffd6000-7fff7000 rwxp 00000000 00:00 0          [stack]

7fff7000-7fff8000 r-xp 00000000 00:00 0          [vdso]




objdump로 디스어셈블



addiu    sp,sp,-40   ( = esp - 40 )

sw    ra,36(sp)        ( = push  ret )

sw    s8,32(sp)        ( = push  ebp )

move    s8,sp          ( =at&t 문법으로 보면 mov  %esp, %ebp )



lui    v0,0x40

addiu    v0,v0,2096(0x830)     =>    (v0 = 0x00400830)

sw     v0,24(s8)                     => Memory[fp+24] = v0

sw     zero,28(s8)                  => Memory[fp+28] = 0

lw      v0,24(s8)                     => v0 = Memory[fp+24]

move    a0,v0                        => a0 = v0

addiu    v0,s8,24                   => v0 = fp + 24

move    a1,v0                        => a1 = v0

move    a2,zero                     => a2 = 0

jal    400500 <execve@plt>

move    at,at



move    sp,s8          (  =at&t 문법으로 보면 mov %ebp, %esp)

lw    ra,36(sp)          ( = pop ret )

lw    s8,32(sp)         ( = pop ebp )

addiu    sp,sp,40      ( = esp + 40 )

jr    ra                      ( goto ret )

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