F5 Networks BIG-IP : Excess resource consumption due to low MSS values vulnerability (K35421172)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from F5 Networks BIG-IP Solution K35421172.
#
# The text description of this plugin is (C) F5 Networks.
#

include('compat.inc');

if (description)
{
  script_id(129313);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/11/03");

  script_cve_id("CVE-2019-11479");
  script_xref(name:"CEA-ID", value:"CEA-2019-0456");

  script_name(english:"F5 Networks BIG-IP : Excess resource consumption due to low MSS values vulnerability (K35421172)");

  script_set_attribute(attribute:"synopsis", value:
"The remote device is missing a vendor-supplied security patch.");
  script_set_attribute(attribute:"description", value:
"Jonathan Looney discovered that the Linux kernel default MSS is
hard-coded to 48 bytes. This allows a remote peer to fragment TCP
resend queues significantly more than if a larger MSS were enforced. A
remote attacker could use this to cause a denial of service. This has
been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127,
4.19.52, 5.1.11, and is fixed in commits
967c05aee439e6e5d7d805e195b3a20ef5c433d6 and
5f3e2bf008c2221478101ee72f5cb4654b9fc363. (CVE-2019-11479)

The Linux kernel is vulnerable to a flaw that allows attackers sending
crafted packets with low maximum segment size (MSS) values to trigger
excessive resource consumption.

Impact

BIG-IP

The BIG-IP system has no exposure to this vulnerability within the
Traffic Management Microkernel (TMM), including virtual servers and
virtual IP addresses (also known as the data plane). However, the
BIG-IP system is vulnerable via the self IP addresses and the
management interface (also known as the control plane). A remote
attacker can exploit this vulnerability to cause a denial of service
(DoS) by sending a sequence of specially crafted TCP packets.

Backend systems accessed via a FastL4 virtual server

By its nature as a full-proxy, the BIG-IP system protects backend
systems accessed through a standard virtual server, as any attacker's
TCP connection would be terminated at the BIG-IP system. However,
backend systems accessed via a FastL4 virtual server(a virtual server
configured with a FastL4 profile) are exposed by default as the attack
traffic is forwarded as-is to the backend system.

Traffix SDC

A remote attacker can exploit this vulnerability to cause a DoS by
sending a sequence of specially crafted TCP packets.");
  script_set_attribute(attribute:"see_also", value:"https://my.f5.com/manage/s/article/K35421172");
  script_set_attribute(attribute:"solution", value:
"Upgrade to one of the non-vulnerable versions listed in the F5 Solution K35421172.");
  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_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-11479");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"in_the_news", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/06/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/06/19");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/09/25");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_access_policy_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_advanced_firewall_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_application_acceleration_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_application_security_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_application_visibility_and_reporting");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_domain_name_system");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_global_traffic_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_link_controller");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_local_traffic_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_policy_enforcement_manager");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:f5:big-ip_webaccelerator");
  script_set_attribute(attribute:"cpe", value:"cpe:/h:f5:big-ip");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"F5 Networks Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2019-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("f5_bigip_detect.nbin");
  script_require_keys("Host/local_checks_enabled", "Host/BIG-IP/hotfix", "Host/BIG-IP/modules", "Host/BIG-IP/version", "Settings/ParanoidReport");

  exit(0);
}


include('f5_func.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var version = get_kb_item('Host/BIG-IP/version');
if ( ! version ) audit(AUDIT_OS_NOT, 'F5 Networks BIG-IP');
if ( isnull(get_kb_item('Host/BIG-IP/hotfix')) ) audit(AUDIT_KB_MISSING, 'Host/BIG-IP/hotfix');
if ( ! get_kb_item('Host/BIG-IP/modules') ) audit(AUDIT_KB_MISSING, 'Host/BIG-IP/modules');

if (report_paranoia < 2) audit(AUDIT_PARANOID);

var sol = 'K35421172';
var vmatrix = {
  'AFM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'AM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'APM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'ASM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'AVR': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'DNS': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'GTM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'LC': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'LTM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'PEM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  },
  'WAM': {
    'affected': [
      '15.0.0-15.0.1','14.0.0-14.1.2','13.1.0-13.1.3','12.1.0-12.1.5','11.5.2-11.6.5'
    ],
    'unaffected': [
      '15.1.0','15.0.1.1','14.1.2.1','14.0.1.1','13.1.3.2','12.1.5.1','11.6.5.1'
    ],
  }
};

if (bigip_is_affected(vmatrix:vmatrix, sol:sol))
{
  var extra = NULL;
  if (report_verbosity > 0) extra = bigip_report_get();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : extra
  );
}
else
{
  var tested = bigip_get_tested_modules();
  var audit_extra = 'For BIG-IP module(s) ' + tested + ',';
  if (tested) audit(AUDIT_INST_VER_NOT_VULN, audit_extra, version);
  else audit(AUDIT_HOST_NOT, 'running any of the affected modules');
}