Palo Alto Networks PAN-OS 7.0.x < 7.0.6 DHCP Packet Handling Dataplane DoS

#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(91971);
  script_version("1.4");
  script_cvs_date("Date: 2018/08/08 12:52:14");


  script_name(english:"Palo Alto Networks PAN-OS 7.0.x < 7.0.6 DHCP Packet Handling Dataplane DoS");
  script_summary(english:"Checks the PAN-OS version.");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is affected by a denial of service vulnerability.");
  script_set_attribute(attribute:"description",value:
"The version of Palo Alto Networks PAN-OS running on the remote host is
7.0.x < 7.0.6. It is, therefore, affected by a flaw in the firewall
functionality that is triggered when the firewall is configured as a
DHCP relay and it receives DHCP requests from a third-party client or
server that exceed the payload length specified in RFC-2132. An
unauthenticated, remote attacker can exploit this, via a crafted DHCP
packet, to cause the dataplane to restart, resulting in a denial of
service condition.");
  # https://www.paloaltonetworks.com/documentation/70/pan-os/pan-os-release-notes/pan-os-7-0-6-addressed-issues#47759
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?2d18c994");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Palo Alto Networks PAN-OS version 7.0.6 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/03/23");
  script_set_attribute(attribute:"patch_publication_date", value:"2016/03/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/07/07");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:paloaltonetworks:pan-os");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2016-2018 Tenable Network Security, Inc.");

  script_dependencies("palo_alto_version.nbin");
  script_require_keys("Host/Palo_Alto/Firewall/Version", "Host/Palo_Alto/Firewall/Full_Version");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("misc_func.inc");

app_name = "Palo Alto Networks PAN-OS";
version = get_kb_item_or_exit("Host/Palo_Alto/Firewall/Version");
full_version = get_kb_item_or_exit("Host/Palo_Alto/Firewall/Full_Version");
fix = '7.0.6';

# Ensure sufficient granularity.
if (version !~ "^\d+\.\d+") audit(AUDIT_VER_NOT_GRANULAR, app_name, full_version);

# 7.0.x is affected.
if (version !~ "^7\.0($|[^0-9])") audit(AUDIT_INST_VER_NOT_VULN, app_name, full_version);

# Compare version to vuln and report as needed.
if (ver_compare(ver:version, fix:fix, strict:FALSE) < 0)
{
  report =
    '\n  Installed version : ' + full_version +
    '\n  Fixed version     : ' + fix +
    '\n';
  security_report_v4(severity:SECURITY_WARNING, extra:report, port:0);
  exit(0);
}
else audit(AUDIT_INST_VER_NOT_VULN, app_name, full_version);