FreeBSD : openvpn -- illegal client float can break VPN session for other users (8604121c-7fc2-11ea-bcac-7781e90b0c8f)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from the FreeBSD VuXML database :
#
# Copyright 2003-2020 Jacques Vidrine and contributors
#
# Redistribution and use in source (VuXML) and 'compiled' forms (SGML,
# HTML, PDF, PostScript, RTF and so forth) with or without modification,
# are permitted provided that the following conditions are met:
# 1. Redistributions of source code (VuXML) must retain the above
#    copyright notice, this list of conditions and the following
#    disclaimer as the first lines of this file unmodified.
# 2. Redistributions in compiled form (transformed to other DTDs,
#    published online in any format, converted to PDF, PostScript,
#    RTF and other formats) must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer
#    in the documentation and/or other materials provided with the
#    distribution.
# 
# THIS DOCUMENTATION IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION,
# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

include('compat.inc');

if (description)
{
  script_id(135714);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/03/15");

  script_cve_id("CVE-2020-11810");

  script_name(english:"FreeBSD : openvpn -- illegal client float can break VPN session for other users (8604121c-7fc2-11ea-bcac-7781e90b0c8f)");

  script_set_attribute(attribute:"synopsis", value:
"The remote FreeBSD host is missing one or more security-related
updates.");
  script_set_attribute(attribute:"description", value:
"Lev Stipakov and Gert Doering report :

There is a time frame between allocating peer-id and initializing data
channel key (which is performed on receiving push request or on async
push-reply) in which the existing peer-id float checks do not work
right.

If a 'rogue' data channel packet arrives during that time frame from
another address and with same peer-id, this would cause client to
float to that new address.

The net effect of this behaviour is that the VPN session for the
'victim client' is broken. Since the 'attacker client' does not have
suitable keys, it can not inject or steal VPN traffic from the other
session. The time window is small and it can not be used to attack a
specific client's session, unless some other way is found to make it
disconnect and reconnect first.");
  # https://github.com/OpenVPN/openvpn/commit/f7b318f811bb43c0d3aa7f337ec6242ed2c33881
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?74ec1b4d");
  # https://sourceforge.net/p/openvpn/openvpn/ci/f7b318f811bb43c0d3aa7f337ec6242ed2c33881/
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?c53088ff");
  # https://www.mail-archive.com/[email protected]/msg19720.html
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?264af6a8");
  script_set_attribute(attribute:"see_also", value:"https://community.openvpn.net/openvpn/ticket/1272");
  script_set_attribute(attribute:"see_also", value:"https://patchwork.openvpn.net/patch/1077/");
  # https://vuxml.freebsd.org/freebsd/8604121c-7fc2-11ea-bcac-7781e90b0c8f.html
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?d5ae1390");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-11810");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/04/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/04/16");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/04/17");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:openvpn");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:openvpn-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:openvpn-mbedtls");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"FreeBSD Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2020-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info");

  exit(0);
}


include("audit.inc");
include("freebsd_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/FreeBSD/release")) audit(AUDIT_OS_NOT, "FreeBSD");
if (!get_kb_item("Host/FreeBSD/pkg_info")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;

if (pkg_test(save_report:TRUE, pkg:"openvpn<2.4.8_3")) flag++;
if (pkg_test(save_report:TRUE, pkg:"openvpn-mbedtls<2.4.8_3")) flag++;
if (pkg_test(save_report:TRUE, pkg:"openvpn-devel<202016")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:pkg_report_get());
  else security_warning(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");