Kerberos Detection (UDP)

# Copyright (C) 2013 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("1.3.6.1.4.1.25623.1.0.108027");
  script_version("2021-04-14T13:21:59+0000");
  script_tag(name:"last_modification", value:"2021-04-14 13:21:59 +0000 (Wed, 14 Apr 2021)");
  script_tag(name:"creation_date", value:"2013-12-12 11:31:47 +0100 (Thu, 12 Dec 2013)");
  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("Kerberos Detection (UDP)");
  script_category(ACT_GATHER_INFO);
  script_family("Service detection");
  script_copyright("Copyright (C) 2013 Greenbone Networks GmbH");
  script_require_udp_ports(88);

  script_tag(name:"summary", value:"UDP based detection of a Kerberos server.");

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

  exit(0);
}

include("host_details.inc");
include("port_service_func.inc");

function parse_resp( res, byte ) {

  local_var res, byte, i, len, realm, stime;

  if( ! res || strlen( res ) < 16 ) return;

  for( i = 4; i < strlen( res ); i++ ) {

    if( res[i] == byte ) {

      i++;
      l = res[i];
      len = ord( l );

      if( ! len || strlen( res ) < len || res[i-3] == '\xA2' ) continue; # \xA2 == ignore ctime

      return substr( res, i + 1, ( i + len ) );

    }
  }
}

function mkd_date_str( rdate ) {

  local_var y, M, d, h, m, s;

  y = substr( rdate, 0, 3 );
  M = substr( rdate, 4, 5 );
  d = substr( rdate, 6, 7 );
  h = substr( rdate, 8, 9 );
  m = substr( rdate, 10, 11 );
  s = substr( rdate, 12, 13 );

  return y + '-' + M + '-' + d + ' ' + h + ':' + m + ':' + s;

}

port = 88;
if( ! get_udp_port_state( port ) )
  exit( 0 );

if( ! soc = open_sock_udp( port ) )
  exit( 0 );

req = raw_string(0x6a,0x81,0xa2,0x30,0x81,0x9f,0xa1,0x03,0x02,0x01,0x05,0xa2,0x03,0x02,0x01,0x0a,
                 0xa4,0x81,0x92,0x30,0x81,0x8f,0xa0,0x07,0x03,0x05,0x00,0x50,0x80,0x00,0x10,0xa1,
                 0x14,0x30,0x12,0xa0,0x03,0x02,0x01,0x01,0xa1,0x0b,0x30,0x09,0x1b,0x07,0x4f,0x70,
                 0x65,0x6e,0x56,0x41,0x53,0xa2,0x09,0x1b,0x07,0x6f,0x70,0x65,0x6e,0x76,0x61,0x73,
                 0xa3,0x1c,0x30,0x1a,0xa0,0x03,0x02,0x01,0x00,0xa1,0x13,0x30,0x11,0x1b,0x06,0x6b,
                 0x72,0x62,0x74,0x67,0x74,0x1b,0x07,0x6f,0x70,0x65,0x6e,0x76,0x61,0x73,0xa4,0x11,
                 0x18,0x0f,0x32,0x30,0x30,0x39,0x31,0x30,0x31,0x32,0x31,0x31,0x33,0x35,0x30,0x35,
                 0x5a,0xa5,0x11,0x18,0x0f,0x32,0x30,0x30,0x39,0x31,0x30,0x31,0x32,0x32,0x31,0x33,
                 0x35,0x30,0x35,0x5a,0xa7,0x06,0x02,0x04,0x0f,0xf1,0xa0,0xa8,0xa8,0x17,0x30,0x15,
                 0x02,0x01,0x12,0x02,0x01,0x11,0x02,0x01,0x10,0x02,0x01,0x17,0x02,0x01,0x01,0x02,
                 0x01,0x03,0x02,0x01,0x02);

send( socket:soc, data:req );

res = recv( socket:soc, length:1024 );
close( soc );

if( ! res || res[0] != '\x7e' )
  exit( 0 );

service_register( port:port, ipproto:"udp", proto:"kerberos" );

stime = parse_resp( res:res, byte:'\x18' );

report = 'A Kerberos Server is running at this port.\n';

if( stime ) report += '\nServer time: ' + mkd_date_str( rdate:stime ) + '\n';

set_kb_item( name:"kerberos/detected", value:TRUE );
set_kb_item( name:"kerberos/udp/detected", value:TRUE );
log_message( port:port, proto:"udp", data:report );

exit( 0 );