Ubuntu 20.04 LTS : Linux kernel (Azure) vulnerabilities (USN-5120-1)

#%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-5120-1. 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(154338);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/28");

  script_cve_id(
    "CVE-2019-19449",
    "CVE-2020-26541",
    "CVE-2020-36311",
    "CVE-2021-3612",
    "CVE-2021-3759",
    "CVE-2021-22543",
    "CVE-2021-38199",
    "CVE-2021-38207",
    "CVE-2021-40490"
  );
  script_xref(name:"USN", value:"5120-1");

  script_name(english:"Ubuntu 20.04 LTS : Linux kernel (Azure) vulnerabilities (USN-5120-1)");

  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-5120-1 advisory.

    It was discovered that the f2fs file system in the Linux kernel did not properly validate metadata in some
    situations. An attacker could use this to construct a malicious f2fs image that, when mounted and operated
    on, could cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-19449)

    It was discovered that the Linux kernel did not properly enforce certain types of entries in the Secure
    Boot Forbidden Signature Database (aka dbx) protection mechanism. An attacker could use this to bypass
    UEFI Secure Boot restrictions. (CVE-2020-26541)

    It was discovered that the KVM hypervisor implementation for AMD processors in the Linux kernel did not
    ensure enough processing time was given to perform cleanups of large SEV VMs. A local attacker could use
    this to cause a denial of service (soft lockup). (CVE-2020-36311)

    It was discovered that the KVM hypervisor implementation in the Linux kernel did not properly perform
    reference counting in some situations, leading to a use-after-free vulnerability. An attacker who could
    start and control a VM could possibly use this to expose sensitive information or execute arbitrary code.
    (CVE-2021-22543)

    Murray McAllister discovered that the joystick device interface in the Linux kernel did not properly
    validate data passed via an ioctl(). A local attacker could use this to cause a denial of service (system
    crash) or possibly execute arbitrary code on systems with a joystick device registered. (CVE-2021-3612)

    It was discovered that the Linux kernel did not properly account for the memory usage of certain IPC
    objects. A local attacker could use this to cause a denial of service (memory exhaustion). (CVE-2021-3759)

    Michael Wakabayashi discovered that the NFSv4 client implementation in the Linux kernel did not properly
    order connection setup operations. An attacker controlling a remote NFS server could use this to cause a
    denial of service on the client. (CVE-2021-38199)

    It was discovered that the Xilinx LL TEMAC device driver in the Linux kernel did not properly calculate
    the number of buffers to be used in certain situations. A remote attacker could use this to cause a denial
    of service (system crash). (CVE-2021-38207)

    It was discovered that the ext4 file system in the Linux kernel contained a race condition when writing
    xattrs to an inode. A local attacker could use this to cause a denial of service or possibly gain
    administrative privileges. (CVE-2021-40490)

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-5120-1");
  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-2021-3612");

  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:"2019/12/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/10/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/10/22");

  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-5.8.0-1043-azure");
  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': {
      'azure': '5.8.0-1043'
    }
  }
};

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-5120-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2019-19449', 'CVE-2020-26541', 'CVE-2020-36311', 'CVE-2021-3612', 'CVE-2021-3759', 'CVE-2021-22543', 'CVE-2021-38199', 'CVE-2021-38207', 'CVE-2021-40490');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-5120-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}