Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4525-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4525-1. 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(140723);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id(
    "CVE-2019-18808",
    "CVE-2019-19054",
    "CVE-2020-12888",
    "CVE-2020-16166",
    "CVE-2020-25212"
  );
  script_xref(name:"USN", value:"4525-1");

  script_name(english:"Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4525-1)");

  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 / 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as
referenced in the USN-4525-1 advisory.

    It was discovered that the AMD Cryptographic Coprocessor device driver in the Linux kernel did not
    properly deallocate memory in some situations. A local attacker could use this to cause a denial of
    service (memory exhaustion). (CVE-2019-18808)

    It was discovered that the Conexant 23885 TV card device driver for the Linux kernel did not properly
    deallocate memory in some error conditions. A local attacker could use this to cause a denial of service
    (memory exhaustion). (CVE-2019-19054)

    It was discovered that the VFIO PCI driver in the Linux kernel did not properly handle attempts to access
    disabled memory spaces. A local attacker could use this to cause a denial of service (system crash).
    (CVE-2020-12888)

    It was discovered that the state of network RNG in the Linux kernel was potentially observable. A remote
    attacker could use this to expose sensitive information. (CVE-2020-16166)

    It was discovered that the NFS client implementation in the Linux kernel did not properly perform bounds
    checking before copying security labels in some situations. A local attacker could use this to cause a
    denial of service (system crash) or possibly execute arbitrary code. (CVE-2020-25212)

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-4525-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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-2020-25212");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/11/07");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/09/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/09/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1019-raspi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1024-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1025-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1025-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1025-oracle");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1026-azure");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-48-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-48-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-48-lowlatency");
  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 || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 18.04 / 20.04', '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': {
    '5.4.0': {
      'generic': '5.4.0-48',
      'generic-lpae': '5.4.0-48',
      'lowlatency': '5.4.0-48',
      'raspi': '5.4.0-1019',
      'aws': '5.4.0-1025',
      'gcp': '5.4.0-1025',
      'oracle': '5.4.0-1025',
      'azure': '5.4.0-1026'
    }
  },
  '20.04': {
    '5.4.0': {
      'generic': '5.4.0-48',
      'generic-lpae': '5.4.0-48',
      'lowlatency': '5.4.0-48',
      'raspi': '5.4.0-1019',
      'kvm': '5.4.0-1024',
      'aws': '5.4.0-1025',
      'gcp': '5.4.0-1025',
      'oracle': '5.4.0-1025',
      'azure': '5.4.0-1026'
    }
  }
};

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-4525-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2019-18808', 'CVE-2019-19054', 'CVE-2020-12888', 'CVE-2020-16166', 'CVE-2020-25212');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4525-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}