OpenSSH Information Disclosure Vulnerability (CVE-2016-20012)

# 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.

CPE = "cpe:/a:openbsd:openssh";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117777");
  script_version("2022-11-24T10:18:54+0000");
  script_tag(name:"last_modification", value:"2022-11-24 10:18:54 +0000 (Thu, 24 Nov 2022)");
  script_tag(name:"creation_date", value:"2021-11-16 11:55:28 +0000 (Tue, 16 Nov 2021)");
  script_tag(name:"cvss_base", value:"4.3");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:P/I:N/A:N");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2021-09-30 19:40:00 +0000 (Thu, 30 Sep 2021)");

  script_cve_id("CVE-2016-20012");

  # e.g. from https://security-tracker.debian.org/tracker/CVE-2016-20012:
  # Negligible impact, not treated as a security issue by upstream
  # MITRE changed the CVE to DISPUTED with NOTE: the vendor does not
  # recognize user enumeration as a vulnerability for this product.
  script_tag(name:"qod_type", value:"remote_probe");

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

  script_name("OpenSSH Information Disclosure Vulnerability (CVE-2016-20012)");

  script_category(ACT_GATHER_INFO);

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

  script_tag(name:"summary", value:"OpenBSD OpenSSH is prone to an information disclosure
  vulnerability.");

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

  script_tag(name:"insight", value:"OpenSSH allows remote attackers, who have a suspicion that a
  certain combination of username and public key is known to an SSH server, to test whether this
  suspicion is correct. This occurs because a challenge is sent only when that combination could be
  valid for a login session.");

  script_tag(name:"affected", value:"All currently OpenSSH versions are known to be affected.");

  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://github.com/openssh/openssh-portable/pull/270");
  script_xref(name:"URL", value:"https://rushter.com/blog/public-ssh-keys/");
  script_xref(name:"URL", value:"https://utcc.utoronto.ca/~cks/space/blog/tech/SSHKeysAreInfoLeak");

  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 );

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

report = report_fixed_ver( installed_version:vers, fixed_version:"None", install_path:path );
security_message( port:port, data:report );
exit( 0 );