CKEditor / FCKeditor 'uploadtest.html' SSRF Vulnerability

# 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.

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117497");
  script_version("2021-06-16T13:40:04+0000");
  script_tag(name:"cvss_base", value:"4.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:S/C:P/I:N/A:N");
  script_tag(name:"last_modification", value:"2021-06-16 13:40:04 +0000 (Wed, 16 Jun 2021)");
  script_tag(name:"creation_date", value:"2021-06-16 11:36:51 +0000 (Wed, 16 Jun 2021)");
  script_name("CKEditor / FCKeditor 'uploadtest.html' SSRF Vulnerability");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_family("Web application abuses");
  script_dependencies("sw_ckeditor_http_detect.nasl", "gb_fckeditor_http_detect.nasl");
  script_require_ports("Services/www", 80);
  script_mandatory_keys("ckeditor_or_fckeditor/http/detected");

  script_xref(name:"URL", value:"https://www.exploit-db.com/exploits/50021");

  script_tag(name:"summary", value:"The 'uploadtest.html' file shipped with CKEditor / FCKeditor is
  prone to a server-side request forgery (SSRF) vulnerability.");

  script_tag(name:"vuldetect", value:"Checks via a crafted HTTP GET request if the affected
  uploadtest.html file exists on the target host.");

  script_tag(name:"impact", value:"This flaw may allow an unauthenticated attacker to send
  unauthorized requests from the target host to external and internal systems, potentially leading
  to network enumeration or facilitating other attacks.");

  script_tag(name:"affected", value:"CKEditor version 3.x and FCKeditor version 2.x are known to
  ship the vulnerable file.");

  script_tag(name:"solution", value:"Remove the affected file from the target host.

  Note: CKEditor 4.0+ doesn't ship this file anymore but it still might exist on the file system
  if it wasn't removed during the update.");

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

  exit(0);
}

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

cpe_list = make_list( "cpe:/a:ckeditor:ckeditor", "cpe:/a:fckeditor:fckeditor" );

if( ! infos = get_app_port_from_list( cpe_list:cpe_list, service:"www" ) )
  exit( 0 );

CPE  = infos["cpe"];
port = infos["port"];

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

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

urls = make_list(
  dir + "/filemanager/connectors/uploadtest.html", # nb: Seen on CKEditor 3.x
  dir + "/editor/filemanager/connectors/uploadtest.html" ); # nb: Seen on FCKeditor 2.x

foreach url( urls ) {

  req = http_get( port:port, item:url );
  res = http_keepalive_send_recv( port:port, data:req );

  if( res && res =~ "^HTTP/1\.[01] 200" &&
      ( "<title>FCKeditor - Uploaders Tests</title>" >< res || # nb: CKEditor 3.x had used the same title
        "Custom Uploader URL:<BR>" >< res ||
        'value="Send it to the Server"' >< res ) ) {
    report = http_report_vuln_url( port:port, url:url );
    security_message( port:port, data:report );
    exit( 0 );
  }
}

exit( 99 );