Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-5050-1)

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-5050-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(152774);
  script_version("1.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2020-26558",
    "CVE-2021-0129",
    "CVE-2021-3564",
    "CVE-2021-3573",
    "CVE-2021-28691",
    "CVE-2021-38208"
  );
  script_xref(name:"USN", value:"5050-1");

  script_name(english:"Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-5050-1)");

  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-5050-1 advisory.

  - Bluetooth LE and BR/EDR secure pairing in Bluetooth Core Specification 2.1 through 5.2 may permit a nearby
    man-in-the-middle attacker to identify the Passkey used during pairing (in the Passkey authentication
    procedure) by reflection of the public key and the authentication evidence of the initiating device,
    potentially permitting this attacker to complete authenticated pairing with the responding device using
    the correct Passkey for the pairing session. The attack methodology determines the Passkey value one bit
    at a time. (CVE-2020-26558)

  - Improper access control in BlueZ may allow an authenticated user to potentially enable information
    disclosure via adjacent access. (CVE-2021-0129)

  - Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force
    Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in
    response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-
    after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0
    will have already exited and thus the call to kthread_stop will be performed against a stale pointer.
    (CVE-2021-28691)

  - A flaw double-free memory corruption in the Linux kernel HCI device initialization subsystem was found in
    the way user attach malicious HCI TTY Bluetooth device. A local user could use this flaw to crash the
    system. This flaw affects all the Linux kernel versions starting from 3.13. (CVE-2021-3564)

  - A use-after-free in function hci_sock_bound_ioctl() of the Linux kernel HCI subsystem was found in the way
    user calls ioct HCIUNBLOCKADDR or other way triggers race condition of the call hci_unregister_dev()
    together with one of the calls hci_sock_blacklist_add(), hci_sock_blacklist_del(), hci_get_conn_info(),
    hci_get_auth_info(). A privileged local user could use this flaw to crash the system or escalate their
    privileges on the system. This flaw affects the Linux kernel versions prior to 5.13-rc5. (CVE-2021-3573)

  - net/nfc/llcp_sock.c in the Linux kernel before 5.12.10 allows local unprivileged users to cause a denial
    of service (NULL pointer dereference and BUG) by making a getsockname call after a certain type of failure
    of a bind call. (CVE-2021-38208)

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-5050-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/C: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-2021-3573");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2021-28691");

  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:"2021/05/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/08/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/08/24");

  script_set_attribute(attribute:"plugin_type", value:"local");
  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-5.8.0-1038-oracle");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-1039-gcp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-1040-azure");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-1042-aws");
  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) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 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': {
    '5.8.0': {
      'oracle': '5.8.0-1038',
      'gcp': '5.8.0-1039',
      'azure': '5.8.0-1040',
      'aws': '5.8.0-1042'
    }
  }
};

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 = 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-5050-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2020-26558', 'CVE-2021-0129', 'CVE-2021-3564', 'CVE-2021-3573', 'CVE-2021-28691', 'CVE-2021-38208');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-5050-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : extra
  );
  exit(0);
}