Apache Guacamole Default Credentials (HTTP)

# Copyright (C) 2021 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.

CPE = "cpe:/a:apache:guacamole";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117610");
  script_version("2022-02-15T15:02:34+0000");
  script_tag(name:"last_modification", value:"2022-02-15 15:02:34 +0000 (Tue, 15 Feb 2022)");
  script_tag(name:"creation_date", value:"2021-08-04 10:19:36 +0000 (Wed, 04 Aug 2021)");
  script_tag(name:"cvss_base", value:"7.5");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_name("Apache Guacamole Default Credentials (HTTP)");
  script_category(ACT_ATTACK);
  script_family("Default Accounts");
  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_dependencies("gb_apache_guacamole_http_detect.nasl", "gb_default_credentials_options.nasl");
  script_require_ports("Services/www", 80);
  script_mandatory_keys("apache/guacamole/http/detected");
  script_exclude_keys("default_credentials/disable_default_account_checks");

  script_tag(name:"summary", value:"The remote Apache Guacamole instance is using known default
  credentials for the HTTP login.");

  script_tag(name:"vuldetect", value:"Tries to login via HTTP using known default credentials.");

  script_tag(name:"impact", value:"This issue may be exploited by a remote attacker to gain access
  to sensitive information or modify system configuration.");

  script_tag(name:"affected", value:"All Apache Guacamole instances with default credentials.");

  script_tag(name:"solution", value:"Change the password.");

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

  exit(0);
}

if( get_kb_item( "default_credentials/disable_default_account_checks" ) )
  exit( 0 );

include("host_details.inc");
include("http_func.inc");
include("http_keepalive.inc");
include("misc_func.inc");

if( ! port = get_app_port( cpe:CPE, service:"www" ) )
  exit( 0 );

if( ! dir = get_app_location( cpe:CPE, port:port ) )
  exit( 0 );

if( dir == "/" )
  dir = "";

creds = make_array();
creds["guacadmin"] = "guacadmin";

url = dir + "/api/tokens";
report = "It was possible to gather a valid 'authToken' with the following known default credentials (username:password:authToken) via a login at '" + http_report_vuln_url( port:port, url:url, url_only:TRUE ) + "':" + '\n';

foreach username( keys( creds ) ) {

  password = creds[username];

  data = "username=" + username + "&password=" + password;

  req = http_post_put_req( port:port, url:url, data:data, add_headers:make_array( "Content-Type", "application/x-www-form-urlencoded" ) );
  res = http_keepalive_send_recv( port:port, data:req );
  if( ! res || res !~ "^HTTP/1\.[01] 200" )
    continue;

  headers = http_extract_headers_from_response( data:res );
  body = http_extract_body_from_response( data:res );
  if( ! headers || ! body || headers !~ "Content-Type\s*:\s*application/json" )
    continue;

  # e.g. the following with a 200 status code for successful login:
  # {"authToken":"C48C40DC75BDA1229B183BEF10834C6EE2A5BE3F6131236DE37014FC8D0F22B8","username":"guacadmin","dataSource":"postgresql","availableDataSources":["postgresql","postgresql-shared"]}
  # or the following on invalid credentials with a 403 status code:
  # {"message":"Invalid login","translatableMessage":{"key":"APP.TEXT_UNTRANSLATED","variables":{"MESSAGE":"Invalid login"}},"statusCode":null,"expected":[{"name":"username","type":"USERNAME"},{"name":"password","type":"PASSWORD"}],"type":"INVALID_CREDENTIALS"}
  # see e.g.:
  # https://github.com/ridvanaltun/guacamole-rest-api-documentation/blob/master/docs/AUTHENTICATION.md#generate-token
  if( egrep( string:body, pattern:'"username"\\s*:\\s*"' + username + '"', icase:FALSE ) &&
      egrep( string:body, pattern:'"authToken"\\s*:\\s*"[^"]+"', icase:FALSE ) ) {

    token = "N/A";
    to = eregmatch( string:body, pattern:'"authToken"\\s*:\\s*"([^"]+)"', icase:FALSE );
    if( to[1] )
      token = to[1];

    report += '\n' + username + ":" + password + ":" + token;
    VULN = TRUE;
  }
}

if( VULN ) {
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );