OpenSSL: Segmentation fault in SSL_check_chain (CVE-2020-1967) - Linux

# SPDX-FileCopyrightText: 2020 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:openssl:openssl";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.108753");
  script_version("2024-02-19T05:05:57+0000");
  script_cve_id("CVE-2020-1967");
  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:"last_modification", value:"2024-02-19 05:05:57 +0000 (Mon, 19 Feb 2024)");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-07-20 23:15:00 +0000 (Tue, 20 Jul 2021)");
  script_tag(name:"creation_date", value:"2020-04-22 06:05:59 +0000 (Wed, 22 Apr 2020)");
  script_name("OpenSSL: Segmentation fault in SSL_check_chain (CVE-2020-1967) - Linux");
  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2020 Greenbone AG");
  script_family("Denial of Service");
  script_dependencies("gb_openssl_consolidation.nasl", "os_detection.nasl");
  script_mandatory_keys("openssl/detected", "Host/runs_unixoide");

  script_xref(name:"URL", value:"https://www.openssl.org/news/secadv/20200421.txt");
  script_xref(name:"URL", value:"https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=eb563247aef3e83dda7679c43f9649270462e5b1");

  script_tag(name:"summary", value:"OpenSSL server or client applications are prone to a
  denial-of-service vulnerability.");

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

  script_tag(name:"insight", value:"Server or client applications that call the SSL_check_chain() function
  during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect
  handling of the 'signature_algorithms_cert' TLS extension. The crash occurs if an invalid or unrecognised
  signature algorithm is received from the peer.");

  script_tag(name:"impact", value:"This could be exploited by a malicious peer in a Denial of
  Service attack.");

  script_tag(name:"affected", value:"OpenSSL versions 1.1.1d, 1.1.1e, and 1.1.1f.

  This issue does not impact OpenSSL versions prior to 1.1.1d.");

  script_tag(name:"solution", value:"Update to version 1.1.1g or later. See the references for more details.");

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

  exit(0);
}

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

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

if( ! infos = get_app_version_and_location( cpe:CPE, port:port, exit_no_version:TRUE ) )
  exit( 0 );

vers = infos["version"];
path = infos["location"];

if( version_in_range( version:vers, test_version:"1.1.1d", test_version2:"1.1.1f" ) ) {
  report = report_fixed_ver( installed_version:vers, fixed_version:"1.1.1g", install_path:path );
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );