Exim <= 4.96 STARTTLS Vulnerability

# SPDX-FileCopyrightText: 2021 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:exim:exim";

if (description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.146491");
  script_version("2024-01-10T05:05:17+0000");
  script_tag(name:"last_modification", value:"2024-01-10 05:05:17 +0000 (Wed, 10 Jan 2024)");
  script_tag(name:"creation_date", value:"2021-08-11 04:29:22 +0000 (Wed, 11 Aug 2021)");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-08-20 17:32:00 +0000 (Fri, 20 Aug 2021)");

  script_cve_id("CVE-2021-38371");

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

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

  script_name("Exim <= 4.96 STARTTLS Vulnerability");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2021 Greenbone AG");
  script_family("General");
  script_dependencies("gb_exim_smtp_detect.nasl");
  script_mandatory_keys("exim/detected");

  script_tag(name:"summary", value:"Exim is prone to a vulnerability in STARTTLS.");

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

  script_tag(name:"insight", value:"The STARTTLS feature in Exim allows response injection
  (buffering) during MTA SMTP sending.");

  script_tag(name:"affected", value:"Exim version 4.96 and prior.");

  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://nostarttls.secvuln.info/");

  exit(0);
}

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

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

if (!version = get_app_version(cpe: CPE, port: port))
  exit(0);

if (version_is_less_equal(version: version, test_version: "4.96")) {
  report = report_fixed_ver(installed_version: version, fixed_version: "None");
  security_message(port: port, data: report);
  exit(0);
}

exit(0);