RHEL 8 : shim (RHSA-2021:1734)

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2021:1734. The text
# itself is copyright (C) Red Hat, Inc.
##

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

if (description)
{
  script_id(149687);
  script_version("1.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/06/04");

  script_cve_id(
    "CVE-2020-14372",
    "CVE-2020-25632",
    "CVE-2020-25647",
    "CVE-2020-27749",
    "CVE-2020-27779",
    "CVE-2021-20225",
    "CVE-2021-20233"
  );
  script_xref(name:"RHSA", value:"2021:1734");
  script_xref(name:"IAVA", value:"2020-A-0349");

  script_name(english:"RHEL 8 : shim (RHSA-2021:1734)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing one or more security updates for shim.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as
referenced in the RHSA-2021:1734 advisory.

    The shim package contains a first-stage UEFI boot loader that handles chaining to a trusted full boot
    loader under secure boot environments.

    Security Fix(es):

    * grub2: acpi command allows privileged user to load crafted ACPI tables when Secure Boot is enabled
    (CVE-2020-14372)

    * grub2: Use-after-free in rmmod command (CVE-2020-25632)

    * grub2: Out-of-bounds write in grub_usb_device_initialize() (CVE-2020-25647)

    * grub2: Stack buffer overflow in grub_parser_split_cmdline() (CVE-2020-27749)

    * grub2: cutmem command allows privileged user to remove memory regions when Secure Boot is enabled
    (CVE-2020-27779)

    * grub2: Heap out-of-bounds write in short form option parser (CVE-2021-20225)

    * grub2: Heap out-of-bounds write due to miscalculation of space required for quoting (CVE-2021-20233)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and
    other related information, refer to the CVE page(s) listed in the References section.

    Additional Changes:

    For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes
    linked from the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://access.redhat.com/security/data/csaf/v2/advisories/2021/rhsa-2021_1734.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?0377cfc1");
  # https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?862005a9");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/updates/classification/#moderate");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/vulnerabilities/RHSB-2021-003");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2021:1734");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1873150");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1879577");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1886936");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1899966");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1900698");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1924696");
  script_set_attribute(attribute:"see_also", value:"https://bugzilla.redhat.com/show_bug.cgi?id=1926263");
  script_set_attribute(attribute:"solution", value:
"Update the RHEL shim package based on the guidance in RHSA-2021:1734.");
  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:C/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-2021-20233");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_cwe_id(121, 184, 285, 416, 787);
  script_set_attribute(attribute:"vendor_severity", value:"Moderate");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/07/30");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/05/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/05/19");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-aa64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-ia32");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-unsigned-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-unsigned-x64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:shim-x64");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"II");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Red Hat Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "redhat_repos.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list", "Host/cpu");

  exit(0);
}


include('rpm.inc');
include('rhel.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/RedHat/release');
if (isnull(os_release) || 'Red Hat' >!< os_release) audit(AUDIT_OS_NOT, 'Red Hat');
var os_ver = pregmatch(pattern: "Red Hat Enterprise Linux.*release ([0-9]+(\.[0-9]+)?)", string:os_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
os_ver = os_ver[1];
if (!rhel_check_release(operator: 'ge', os_version: os_ver, rhel_version: '8')) audit(AUDIT_OS_NOT, 'Red Hat 8.x', 'Red Hat ' + os_ver);

if (!get_kb_item('Host/RedHat/rpm-list')) 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 && 'ppc' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Red Hat', cpu);

var constraints = [
  {
    'repo_relative_urls': [
      'content/dist/rhel8/8.10/aarch64/baseos/debug',
      'content/dist/rhel8/8.10/aarch64/baseos/os',
      'content/dist/rhel8/8.10/aarch64/baseos/source/SRPMS',
      'content/dist/rhel8/8.10/x86_64/baseos/debug',
      'content/dist/rhel8/8.10/x86_64/baseos/os',
      'content/dist/rhel8/8.10/x86_64/baseos/source/SRPMS',
      'content/dist/rhel8/8.6/aarch64/baseos/debug',
      'content/dist/rhel8/8.6/aarch64/baseos/os',
      'content/dist/rhel8/8.6/aarch64/baseos/source/SRPMS',
      'content/dist/rhel8/8.6/x86_64/baseos/debug',
      'content/dist/rhel8/8.6/x86_64/baseos/os',
      'content/dist/rhel8/8.6/x86_64/baseos/source/SRPMS',
      'content/dist/rhel8/8.8/aarch64/baseos/debug',
      'content/dist/rhel8/8.8/aarch64/baseos/os',
      'content/dist/rhel8/8.8/aarch64/baseos/source/SRPMS',
      'content/dist/rhel8/8.8/x86_64/baseos/debug',
      'content/dist/rhel8/8.8/x86_64/baseos/os',
      'content/dist/rhel8/8.8/x86_64/baseos/source/SRPMS',
      'content/dist/rhel8/8.9/aarch64/baseos/debug',
      'content/dist/rhel8/8.9/aarch64/baseos/os',
      'content/dist/rhel8/8.9/aarch64/baseos/source/SRPMS',
      'content/dist/rhel8/8.9/x86_64/baseos/debug',
      'content/dist/rhel8/8.9/x86_64/baseos/os',
      'content/dist/rhel8/8.9/x86_64/baseos/source/SRPMS',
      'content/dist/rhel8/8/aarch64/baseos/debug',
      'content/dist/rhel8/8/aarch64/baseos/os',
      'content/dist/rhel8/8/aarch64/baseos/source/SRPMS',
      'content/dist/rhel8/8/x86_64/baseos/debug',
      'content/dist/rhel8/8/x86_64/baseos/os',
      'content/dist/rhel8/8/x86_64/baseos/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'shim-aa64-15.4-2.el8_1', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'shim-ia32-15.4-2.el8_1', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'shim-x64-15.4-2.el8_1', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
    ]
  },
  {
    'repo_relative_urls': [
      'content/dist/rhel8/8.10/aarch64/codeready-builder/debug',
      'content/dist/rhel8/8.10/aarch64/codeready-builder/os',
      'content/dist/rhel8/8.10/aarch64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.10/x86_64/codeready-builder/debug',
      'content/dist/rhel8/8.10/x86_64/codeready-builder/os',
      'content/dist/rhel8/8.10/x86_64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.6/aarch64/codeready-builder/debug',
      'content/dist/rhel8/8.6/aarch64/codeready-builder/os',
      'content/dist/rhel8/8.6/aarch64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.6/x86_64/codeready-builder/debug',
      'content/dist/rhel8/8.6/x86_64/codeready-builder/os',
      'content/dist/rhel8/8.6/x86_64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.8/aarch64/codeready-builder/debug',
      'content/dist/rhel8/8.8/aarch64/codeready-builder/os',
      'content/dist/rhel8/8.8/aarch64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.8/x86_64/codeready-builder/debug',
      'content/dist/rhel8/8.8/x86_64/codeready-builder/os',
      'content/dist/rhel8/8.8/x86_64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.9/aarch64/codeready-builder/debug',
      'content/dist/rhel8/8.9/aarch64/codeready-builder/os',
      'content/dist/rhel8/8.9/aarch64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8.9/x86_64/codeready-builder/debug',
      'content/dist/rhel8/8.9/x86_64/codeready-builder/os',
      'content/dist/rhel8/8.9/x86_64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8/aarch64/codeready-builder/debug',
      'content/dist/rhel8/8/aarch64/codeready-builder/os',
      'content/dist/rhel8/8/aarch64/codeready-builder/source/SRPMS',
      'content/dist/rhel8/8/x86_64/codeready-builder/debug',
      'content/dist/rhel8/8/x86_64/codeready-builder/os',
      'content/dist/rhel8/8/x86_64/codeready-builder/source/SRPMS'
    ],
    'pkgs': [
      {'reference':'shim-unsigned-aarch64-15-7.el8_1', 'cpu':'aarch64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
      {'reference':'shim-unsigned-x64-15.4-4.el8_1', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var applicable_repo_urls = rhel_determine_applicable_repository_urls(constraints:constraints);
if(applicable_repo_urls == RHEL_REPOS_NO_OVERLAP_MESSAGE) exit(0, RHEL_REPO_NOT_ENABLED);

var flag = 0;
foreach var constraint_array ( constraints ) {
  var repo_relative_urls = NULL;
  if (!empty_or_null(constraint_array['repo_relative_urls'])) repo_relative_urls = constraint_array['repo_relative_urls'];
  foreach var pkg ( constraint_array['pkgs'] ) {
    var reference = NULL;
    var _release = NULL;
    var sp = NULL;
    var _cpu = NULL;
    var el_string = NULL;
    var rpm_spec_vers_cmp = NULL;
    var epoch = NULL;
    var allowmaj = NULL;
    var exists_check = NULL;
    var cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    if (!empty_or_null(pkg['release'])) _release = 'RHEL' + pkg['release'];
    if (!empty_or_null(pkg['sp'])) sp = pkg['sp'];
    if (!empty_or_null(pkg['cpu'])) _cpu = pkg['cpu'];
    if (!empty_or_null(pkg['el_string'])) el_string = pkg['el_string'];
    if (!empty_or_null(pkg['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = pkg['rpm_spec_vers_cmp'];
    if (!empty_or_null(pkg['epoch'])) epoch = pkg['epoch'];
    if (!empty_or_null(pkg['allowmaj'])) allowmaj = pkg['allowmaj'];
    if (!empty_or_null(pkg['exists_check'])) exists_check = pkg['exists_check'];
    if (!empty_or_null(pkg['cves'])) cves = pkg['cves'];
    if (reference &&
        _release &&
        rhel_decide_repo_relative_url_check(required_repo_url_list:repo_relative_urls) &&
        (applicable_repo_urls || (!exists_check || rpm_exists(release:_release, rpm:exists_check))) &&
        rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj, cves:cves)) flag++;
  }
}

if (flag)
{
  var extra = NULL;
  if (isnull(applicable_repo_urls) || !applicable_repo_urls) extra = rpm_report_get() + redhat_report_repo_caveat();
  else extra = rpm_report_get();
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : extra
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'shim-aa64 / shim-ia32 / shim-unsigned-aarch64 / shim-unsigned-x64 / etc');
}