OpenSSH 6.2 <= 8.7 Privilege Escalation Vulnerability

# 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.
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# This program is distributed in the hope that it will be useful,
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
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CPE = "cpe:/a:openbsd:openssh";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117696");
  script_version("2021-10-11T08:01:31+0000");
  script_tag(name:"last_modification", value:"2021-10-11 08:01:31 +0000 (Mon, 11 Oct 2021)");
  script_tag(name:"creation_date", value:"2021-09-27 06:23:21 +0000 (Mon, 27 Sep 2021)");
  script_tag(name:"cvss_base", value:"4.4");
  script_tag(name:"cvss_base_vector", value:"AV:L/AC:M/Au:N/C:P/I:P/A:P");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-10-07 14:46:00 +0000 (Thu, 07 Oct 2021)");

  script_cve_id("CVE-2021-41617");

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

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

  script_name("OpenSSH 6.2 <= 8.7 Privilege Escalation Vulnerability");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_family("Privilege escalation");
  script_dependencies("gb_openssh_consolidation.nasl");
  script_mandatory_keys("openssh/detected");

  script_tag(name:"summary", value:"OpenSSH is prone to a privilege scalation vulnerability in
  certain configurations.");

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

  script_tag(name:"insight", value:"sshd failed to correctly initialise supplemental groups when
  executing an AuthorizedKeysCommand or AuthorizedPrincipalsCommand, where a
  AuthorizedKeysCommandUser or AuthorizedPrincipalsCommandUser directive has been set to run the
  command as a different user. Instead these commands would inherit the groups that sshd was started
  with.

  Depending on system configuration, inherited groups may allow
  AuthorizedKeysCommand/AuthorizedPrincipalsCommand helper programs to gain unintended privilege.

  Neither AuthorizedKeysCommand nor AuthorizedPrincipalsCommand are enabled by default in
  sshd_config.");

  script_tag(name:"affected", value:"OpenSSH versions 6.2 through 8.7.");

  script_tag(name:"solution", value:"Update to version 8.8 or later.");

  script_xref(name:"URL", value:"https://www.openssh.com/txt/release-8.8");

  exit(0);
}

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

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

if (version_in_range(version: version, test_version: "6.2", test_version2: "8.7")) {
  report = report_fixed_ver(installed_version: version, fixed_version: "8.8", install_path: location);
  security_message(port: port, data: report);
  exit(0);
}

exit(99);