Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-4389-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4389-1. 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(137299);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id(
    "CVE-2020-0067",
    "CVE-2020-0543",
    "CVE-2020-10751",
    "CVE-2020-12114",
    "CVE-2020-12464",
    "CVE-2020-12659"
  );
  script_xref(name:"USN", value:"4389-1");

  script_name(english:"Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-4389-1)");

  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 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-4389-1 advisory.

    It was discovered that the F2FS file system implementation in the Linux kernel did not properly perform
    bounds checking on xattrs in some situations. A local attacker could possibly use this to expose sensitive
    information (kernel memory). (CVE-2020-0067)

    It was discovered that memory contents previously stored in microarchitectural special registers after
    RDRAND, RDSEED, and SGX EGETKEY read operations on Intel client and Xeon E3 processors may be briefly
    exposed to processes on the same or different processor cores. A local attacker could use this to expose
    sensitive information. (CVE-2020-0543)

    Piotr Krysiuk discovered that race conditions existed in the file system implementation in the Linux
    kernel. A local attacker could use this to cause a denial of service (system crash). (CVE-2020-12114)

    It was discovered that the USB susbsystem's scatter-gather implementation in the Linux kernel did not
    properly take data references in some situations, leading to a use-after-free. A physically proximate
    attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.
    (CVE-2020-12464)

    Bui Quang Minh discovered that the XDP socket implementation in the Linux kernel did not properly validate
    meta-data passed from user space, leading to an out-of-bounds write vulnerability. A local attacker with
    the CAP_NET_ADMIN capability could use this to cause a denial of service (system crash) or possibly
    execute arbitrary code. (CVE-2020-12659)

    Dmitry Vyukov discovered that the SELinux netlink security hook in the Linux kernel did not validate
    messages in some situations. A privileged attacker could use this to bypass SELinux netlink restrictions.
    (CVE-2020-10751)

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-4389-1");
  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:H/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-2020-12659");

  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:"2020/04/17");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/06/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/10");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1012-raspi");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1015-aws");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1015-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1015-kvm");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1015-oracle");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1016-azure");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-27-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-37-generic");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-37-generic-lpae");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-37-lowlatency");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-: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 (! ('20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 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 = {
  '20.04': {
    '5.4.0': {
      'generic': '5.4.0-37',
      'generic-lpae': '5.4.0-37',
      'lowlatency': '5.4.0-37',
      'raspi': '5.4.0-1012',
      'aws': '5.4.0-1015',
      'gcp': '5.4.0-1015',
      'kvm': '5.4.0-1015',
      'oracle': '5.4.0-1015',
      'azure': '5.4.0-1016'
    }
  }
};

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-4389-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2020-0067', 'CVE-2020-0543', 'CVE-2020-10751', 'CVE-2020-12114', 'CVE-2020-12464', 'CVE-2020-12659');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-4389-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}