Amazon AWS / S3 (compatible) Bucket Publicly Accessible (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.

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117470");
  script_version("2021-06-08T09:48:03+0000");
  script_tag(name:"last_modification", value:"2021-06-08 09:48:03 +0000 (Tue, 08 Jun 2021)");
  script_tag(name:"creation_date", value:"2021-06-08 09:24:04 +0000 (Tue, 08 Jun 2021)");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:N/A:N");
  script_tag(name:"cvss_base", value:"5.0");
  script_name("Amazon AWS / S3 (compatible) Bucket Publicly Accessible (HTTP)");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_family("General");
  script_dependencies("find_service.nasl", "httpver.nasl", "global_settings.nasl");
  script_require_ports("Services/www", 80);
  script_exclude_keys("Settings/disable_cgi_scanning");

  script_xref(name:"URL", value:"https://mikey96.medium.com/cloud-based-storage-misconfigurations-critical-bounties-361647f78a29");
  script_xref(name:"URL", value:"https://docs.aws.amazon.com/AmazonS3/latest/userguide/acls.html");

  script_tag(name:"summary", value:"The Amazon Web Services (AWS) / Simple Storage Service (S3)
  (compatible) bucket is publicly accessible.");

  script_tag(name:"vuldetect", value:"Checks via HTTP if an AWS / S3 bucket is publicly
  accessible.");

  script_tag(name:"impact", value:"Based on the information provided in this bucket an attacker
  might be able to extract sensitive data from the bucket.");

  script_tag(name:"solution", value:"Enable access control lists (ACL) on the bucket to prevent
  public access to sensitive data.");

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

  exit(0);
}

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

port = http_get_port( default:80 );

url = "/";
res = http_get_cache( item:url, port:port );
if( ! res || res !~ "^HTTP/1\.[01] 200" )
  exit( 0 );

headers = http_extract_headers_from_response( data:res );
body = http_extract_body_from_response( data:res );
if( ! headers || ! body )
  exit( 0 );

# e.g.
# <ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
# or just:
# <ListBucketResult>
if( egrep( string:headers, pattern:"^Content-Type\s*:\s*application/xml", icase:TRUE ) &&
    egrep( string:body, pattern:"^\s*<ListBucketResult[^>]*>", icase:FALSE ) ) {
  report = http_report_vuln_url( port:port, url:url );
  report += '\nExtracted data (truncated):\n\n' + substr( body, 0, 1500 );
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );