Ubuntu 18.04 LTS : Linux kernel vulnerabilities (USN-4439-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4439-1. 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(139027);
  script_version("1.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id(
    "CVE-2019-12380",
    "CVE-2019-16089",
    "CVE-2019-19036",
    "CVE-2019-19462",
    "CVE-2019-20810",
    "CVE-2019-20908",
    "CVE-2020-10732",
    "CVE-2020-10757",
    "CVE-2020-10766",
    "CVE-2020-10767",
    "CVE-2020-10768",
    "CVE-2020-11935",
    "CVE-2020-13974",
    "CVE-2020-15780"
  );
  script_xref(name:"USN", value:"4439-1");

  script_name(english:"Ubuntu 18.04 LTS : Linux kernel vulnerabilities (USN-4439-1)");

  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 18.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-4439-1 advisory.

    It was discovered that the network block device (nbd) implementation in the Linux kernel did not properly
    check for error conditions in some situations. An attacker could possibly use this to cause a denial of
    service (system crash). (CVE-2019-16089)

    It was discovered that the btrfs file system implementation in the Linux kernel did not properly validate
    file system metadata in some situations. An attacker could use this to construct a malicious btrfs image
    that, when mounted, could cause a denial of service (system crash). (CVE-2019-19036)

    It was discovered that the kernel->user space relay implementation in the Linux kernel did not properly
    check return values in some situations. A local attacker could possibly use this to cause a denial of
    service (system crash). (CVE-2019-19462)

    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)

    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)

    Fan Yang discovered that the mremap implementation in the Linux kernel did not properly handle DAX Huge
    Pages. A local attacker with access to DAX storage could use this to gain administrative privileges.
    (CVE-2020-10757)

    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)

    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)

    Jason A. Donenfeld discovered that the ACPI implementation in the Linux kernel did not properly restrict
    loading ACPI tables via configfs. A privileged attacker could use this to bypass Secure Boot lockdown
    restrictions and execute arbitrary code in the kernel. (CVE-2020-15780)

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-4439-1");
  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-2020-15780");
  script_set_attribute(attribute:"cvss3_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:"2020/07/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.0.0-1045-gke");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.0.0-1065-oem-osp1");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-: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 (! ('18.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 18.04', '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 = {
  '18.04': {
    '5.0.0': {
      'gke': '5.0.0-1045',
      'oem-osp1': '5.0.0-1065'
    }
  }
};

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-4439-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2019-12380', 'CVE-2019-16089', 'CVE-2019-19036', 'CVE-2019-19462', 'CVE-2019-20810', 'CVE-2019-20908', 'CVE-2020-10732', 'CVE-2020-10757', 'CVE-2020-10766', 'CVE-2020-10767', 'CVE-2020-10768', 'CVE-2020-11935', 'CVE-2020-13974', 'CVE-2020-15780');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4439-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}