Knot DNS Server < 2.3.0 AXFR Response DoS Vulnerability

# SPDX-FileCopyrightText: 2016 Greenbone AG
# 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-only

CPE = "cpe:/a:knot:dns";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.106119");
  script_version("2025-10-31T05:40:56+0000");
  script_tag(name:"last_modification", value:"2025-10-31 05:40:56 +0000 (Fri, 31 Oct 2025)");
  script_tag(name:"creation_date", value:"2016-07-08 10:27:46 +0700 (Fri, 08 Jul 2016)");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2020-06-11 19:43:00 +0000 (Thu, 11 Jun 2020)");
  script_cve_id("CVE-2016-6171");
  script_name("Knot DNS Server < 2.3.0 AXFR Response DoS Vulnerability");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2016 Greenbone AG");
  script_family("Denial of Service");
  script_dependencies("gb_knot_dns_detect.nasl");
  script_mandatory_keys("knotdns/detected");

  script_tag(name:"summary", value:"Knot DNS Server is prone to a denial of service (DoS)
  vulnerability.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");

  script_tag(name:"insight", value:"Primary DNS servers may cause a denial of service (secondary DNS
  server crash) via a large AXFR response, and possibly allows IXFR servers to cause a denial of
  service (IXFR client crash) via a large IXFR response and allows remote authenticated users to
  cause a denial of service (primary DNS server crash) via a large UPDATE message.");

  script_tag(name:"impact", value:"An authenticated remote attacker may cause a denial of service
  condition.");

  script_tag(name:"affected", value:"Knot DNS versions prior to 2.3.0.");

  script_tag(name:"solution", value:"Update to version 2.3.0 or later.");

  script_xref(name:"URL", value:"http://www.openwall.com/lists/oss-security/2016/07/06/3");
  script_xref(name:"URL", value:"https://lists.dns-oarc.net/pipermail/dns-operations/2016-July/015058.html");
  script_xref(name:"URL", value:"https://www.knot-dns.cz/2016-08-09-version-230.html");

  script_tag(name:"qod_type", value:"remote_banner_unreliable");
  script_tag(name:"solution_type", value:"VendorFix");

  exit(0);
}

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

if( ! port = get_app_port( cpe:CPE ) )
  exit( 0 );

if( ! infos = get_app_version_and_proto( cpe:CPE, port:port ) )
  exit( 0 );

version = infos["version"];
proto = infos["proto"];

if( version_is_less( version:version, test_version:"2.3.0" ) ) {
  report = report_fixed_ver( installed_version:version, fixed_version:"2.3.0" );
  security_message( data:report, port:port, proto:proto );
  exit( 0 );
}

exit( 99 );