Ubuntu 16.04 LTS : Linux kernel vulnerabilities (USN-4427-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4427-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include('compat.inc');

if (description)
{
  script_id(138836);
  script_version("1.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id(
    "CVE-2019-12380",
    "CVE-2019-19947",
    "CVE-2019-20810",
    "CVE-2019-20908",
    "CVE-2020-10732",
    "CVE-2020-10766",
    "CVE-2020-10767",
    "CVE-2020-10768",
    "CVE-2020-11935",
    "CVE-2020-13974"
  );
  script_xref(name:"USN", value:"4427-1");

  script_name(english:"Ubuntu 16.04 LTS : Linux kernel vulnerabilities (USN-4427-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-4427-1 advisory.

    It was discovered that the Kvaser CAN/USB driver in the Linux kernel did not properly initialize memory in
    certain situations. A local attacker could possibly use this to expose sensitive information (kernel
    memory). (CVE-2019-19947)

    Chuhong Yuan discovered that go7007 USB audio device driver in the Linux kernel did not properly
    deallocate memory in some failure conditions. A physically proximate attacker could use this to cause a
    denial of service (memory exhaustion). (CVE-2019-20810)

    Jason A. Donenfeld discovered that the ACPI implementation in the Linux kernel did not properly restrict
    loading SSDT code from an EFI variable. A privileged attacker could use this to bypass Secure Boot
    lockdown restrictions and execute arbitrary code in the kernel. (CVE-2019-20908)

    It was discovered that the elf handling code in the Linux kernel did not initialize memory before using it
    in certain situations. A local attacker could use this to possibly expose sensitive information (kernel
    memory). (CVE-2020-10732)

    It was discovered that the Linux kernel did not correctly apply Speculative Store Bypass Disable (SSBD)
    mitigations in certain situations. A local attacker could possibly use this to expose sensitive
    information. (CVE-2020-10766)

    It was discovered that the Linux kernel did not correctly apply Indirect Branch Predictor Barrier (IBPB)
    mitigations in certain situations. A local attacker could possibly use this to expose sensitive
    information. (CVE-2020-10767)

    It was discovered that the Linux kernel could incorrectly enable Indirect Branch Speculation after it has
    been disabled for a process via a prctl() call. A local attacker could possibly use this to expose
    sensitive information. (CVE-2020-10768)

    Mauricio Faria de Oliveira discovered that the aufs implementation in the Linux kernel improperly managed
    inode reference counts in the vfsub_dentry_open() method. A local attacker could use this vulnerability to
    cause a denial of service. (CVE-2020-11935)

    It was discovered that the Virtual Terminal keyboard driver in the Linux kernel contained an integer
    overflow. A local attacker could possibly use this to have an unspecified impact. (CVE-2020-13974)

    It was discovered that the efi subsystem in the Linux kernel did not handle memory allocation failures
    during early boot in some situations. A local attacker could possibly use this to cause a denial of
    service (system crash). (CVE-2019-12380)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-4427-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-13974");

  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:"2019/05/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/07/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/07/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1077-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1111-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1136-raspi2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-1140-snapdragon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-lowlatency");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc-e500mc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc-smp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc64-emb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-4.4.0-186-powerpc64-smp");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2020-2024 Canonical, Inc. / NASL script (C) 2020-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');
include('ksplice.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('16.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var kernel_mappings = {
  '16.04': {
    '4.4.0': {
      'generic': '4.4.0-186',
      'generic-lpae': '4.4.0-186',
      'lowlatency': '4.4.0-186',
      'powerpc-e500mc': '4.4.0-186',
      'powerpc-smp': '4.4.0-186',
      'powerpc64-emb': '4.4.0-186',
      'powerpc64-smp': '4.4.0-186',
      'kvm': '4.4.0-1077',
      'aws': '4.4.0-1111',
      'raspi2': '4.4.0-1136',
      'snapdragon': '4.4.0-1140'
    }
  }
};

var host_kernel_release = get_kb_item('Host/uptrack-uname-r');
if (empty_or_null(host_kernel_release)) host_kernel_release = get_kb_item_or_exit('Host/uname-r');
var host_kernel_base_version = get_kb_item_or_exit('Host/Debian/kernel-base-version');
var host_kernel_type = get_kb_item_or_exit('Host/Debian/kernel-type');
if(empty_or_null(kernel_mappings[os_release][host_kernel_base_version][host_kernel_type])) audit(AUDIT_INST_VER_NOT_VULN, 'kernel ' + host_kernel_release);

var extra = '';
var kernel_fixed_version = kernel_mappings[os_release][host_kernel_base_version][host_kernel_type] + "-" + host_kernel_type;
if (deb_ver_cmp(ver1:host_kernel_release, ver2:kernel_fixed_version) < 0)
{
  extra += 'Running Kernel level of ' + host_kernel_release + ' does not meet the minimum fixed level of ' + kernel_fixed_version + ' for this advisory.\n\n';
}
  else
{
  audit(AUDIT_PATCH_INSTALLED, 'Kernel package for USN-4427-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2019-12380', 'CVE-2019-19947', 'CVE-2019-20810', 'CVE-2019-20908', 'CVE-2020-10732', 'CVE-2020-10766', 'CVE-2020-10767', 'CVE-2020-10768', 'CVE-2020-11935', 'CVE-2020-13974');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4427-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}