Anonymous FTP Login Detection

# Copyright (C) 2009 Greenbone Networks GmbH
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-or-later
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# 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_oid("1.3.6.1.4.1.25623.1.0.108477");
  script_version("2021-09-01T14:04:04+0000");
  script_tag(name:"last_modification", value:"2021-09-01 14:04:04 +0000 (Wed, 01 Sep 2021)");
  script_tag(name:"creation_date", value:"2009-03-12 10:50:11 +0100 (Thu, 12 Mar 2009)");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:N");
  script_tag(name:"cvss_base", value:"0.0");
  script_name("Anonymous FTP Login Detection");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2009 Greenbone Networks GmbH");
  script_family("Service detection");
  script_dependencies("find_service2.nasl", "find_service_3digits.nasl", "logins.nasl");
  script_require_ports("Services/ftp", 21);

  script_tag(name:"summary", value:"Checks if the remote FTP Server allows anonymous logins.

  Note: The reporting takes place in a separate VT 'Anonymous FTP Login Reporting' (OID: 1.3.6.1.4.1.25623.1.0.900600).");

  script_tag(name:"vuldetect", value:"Try to login with an anonymous account at the remote FTP Server.");

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

  exit(0);
}

include("ftp_func.inc");
include("misc_func.inc");
include("port_service_func.inc");

report = 'It was possible to login to the remote FTP service with the following anonymous account(s):\n\n';
listingReport = '\nHere are the contents of the remote FTP directory listing:\n';
passwd = "[email protected]";

port = ftp_get_port( default:21 );

foreach user( make_list( "anonymous", "ftp" ) ) {

  soc1 = open_sock_tcp( port );
  if( ! soc1 )
    continue;

  login_details = ftp_log_in( socket:soc1, user:user, pass:passwd );
  if( ! login_details ) {
    ftp_close( socket:soc1 );
    continue;
  }

  vuln = TRUE;
  report += user + ':' + passwd + '\n';

  set_kb_item( name:"ftp/" + port + "/anonymous", value:TRUE );
  set_kb_item( name:"ftp/anonymous_ftp/detected", value:TRUE );

  # TODO: We might want to check if ftp/login contains the "anonymous" user
  # and ftp/password [email protected] and then do a replace_kb_item()
  # below to catch cases where only the ftp user is allowed to connect to
  # the service.
  if( ! get_kb_item( "ftp/login" ) ) {
    set_kb_item( name:"ftp/login", value:user );
    set_kb_item( name:"ftp/password", value:passwd );
  }
  if( ! get_kb_item( "ftp/anonymous/login" ) ) {
    set_kb_item( name:"ftp/anonymous/login", value:user );
    set_kb_item( name:"ftp/anonymous/password", value:passwd );
  }

  port2 = ftp_get_pasv_port( socket:soc1 );
  if( ! port2 ) {
    ftp_close( socket:soc1 );
    continue;
  }

  soc2 = open_sock_tcp( port2, transport:get_port_transport( port ) );
  if( ! soc2 ) {
    ftp_close( socket:soc1 );
    continue;
  }

  send( socket:soc1, data:'LIST /\r\n' );
  listing = ftp_recv_listing( socket:soc2 );
  close( soc2 );
  ftp_close( socket:soc1 );

  if( listing && strlen( listing ) ) {
    listingAvailable = TRUE;
    listingReport += '\nAccount "' + user + '":\n\n' + listing;
  }
}

if( vuln ) {
  if( listingAvailable )
    report += listingReport;
  set_kb_item( name:"ftp/" + port + "/anonymous_report", value:report );
}

exit( 0 );