OpenSSH 'auth2-gss.c' User Enumeration Vulnerability - Linux

# Copyright (C) 2018 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("1.3.6.1.4.1.25623.1.0.813888");
  script_version("2021-05-28T07:06:21+0000");
  script_cve_id("CVE-2018-15919");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:N/A:N");
  script_tag(name:"last_modification", value:"2021-05-28 07:06:21 +0000 (Fri, 28 May 2021)");
  script_tag(name:"severity_vector", value:"CVSS:3.0/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:"2019-03-07 16:29:00 +0000 (Thu, 07 Mar 2019)");
  script_tag(name:"creation_date", value:"2018-09-05 13:12:09 +0530 (Wed, 05 Sep 2018)");
  script_name("OpenSSH 'auth2-gss.c' User Enumeration Vulnerability - Linux");
  script_copyright("Copyright (C) 2018 Greenbone Networks GmbH");
  script_category(ACT_GATHER_INFO);
  script_family("General");
  script_dependencies("gb_openssh_consolidation.nasl", "os_detection.nasl");
  script_mandatory_keys("openssh/detected", "Host/runs_unixoide");

  script_xref(name:"URL", value:"https://bugzilla.novell.com/show_bug.cgi?id=1106163");
  script_xref(name:"URL", value:"https://seclists.org/oss-sec/2018/q3/180");

  script_tag(name:"summary", value:"OpenSSH is prone to a user enumeration vulnerability.");

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

  script_tag(name:"insight", value:"The flaw exists in the 'auth-gss2.c' source code file of the
  affected software and is due to insufficient validation of an authentication request packet when
  the Guide Star Server II (GSS2) component is used on an affected system.");

  script_tag(name:"impact", value:"Successfully exploitation will allow a remote attacker to harvest
  valid user accounts, which may aid in brute-force attacks.");

  script_tag(name:"affected", value:"OpenSSH version 5.9 through 7.8.");

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

  exit(0);
}

include("version_func.inc");
include("revisions-lib.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"];

if((revcomp(a:vers, b:"7.8p1") <= 0) && (revcomp(a:vers, b:"5.9") >= 0)) {
  report = report_fixed_ver(installed_version:vers, fixed_version:"None", install_path:path);
  security_message(port:port, data:report);
  exit(0);
}

exit(99);