AlmaLinux 9.6 [TuxCare] Security Update: shim-x64 Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2025:1751552694)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(361768);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/01");

  script_cve_id(
    "CVE-2022-28737",
    "CVE-2023-40546",
    "CVE-2023-40547",
    "CVE-2023-40548",
    "CVE-2023-40549",
    "CVE-2023-40550",
    "CVE-2023-40551"
  );
  script_xref(name:"CLSA", value:"2025:1751552694");

  script_name(english:"AlmaLinux 9.6 [TuxCare] Security Update: shim-x64 Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2025:1751552694)");

  script_set_attribute(attribute:"synopsis", value:
"The AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The AlmaLinux 9.6 host has a package installed that is affected by multiple vulnerabilities as referenced in the TuxCare
ALMALINUX9.6:CLSA-2025:1751552694 advisory.

  - There's a possible overflow in handle_image() when shim tries to load and execute crafted EFI executables;
    The handle_image() function takes into account the SizeOfRawData field from each section to be loaded. An
    attacker can leverage this to perform out-of-bound writes into memory. Arbitrary code execution is not
    discarded in such scenario. (CVE-2022-28737)

  - A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create
    the new variable, it tries to print an error message to the user; however, the number of parameters used
    by the logging function doesn't match the format string used by it, leading to a crash under certain
    circumstances. (CVE-2023-40546)

  - A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled
    values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP
    request, leading to a completely controlled out-of-bounds write primitive and complete system compromise.
    This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the-
    Middle or compromise the boot server to be able to exploit this vulnerability successfully.
    (CVE-2023-40547)

  - A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition
    operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is
    further used for memory allocation operations, leading to a heap-based buffer overflow. This flaw causes
    memory corruption and can lead to a crash or data integrity issues during the boot phase. (CVE-2023-40548)

  - An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the
    load of a PE binary. This flaw allows an attacker to load a crafted PE binary, triggering the issue and
    crashing Shim, resulting in a denial of service. (CVE-2023-40549)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  # https://security.tuxcare.com/csaf/v2/els_os/tuxcare9.6esu/advisories/2025/clsa-2025_1751552694.json
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6a44e67e");
  script_set_attribute(attribute:"see_also", value:"https://cve.tuxcare.com/els/releases/CLSA-2025:1751552694");
  script_set_attribute(attribute:"solution", value:
"Update the affected shim-x64 package based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2025:1751552694.");
  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:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:C/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-2022-28737");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2023-40547");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2022/06/16");
  script_set_attribute(attribute:"patch_publication_date", value:"2025/07/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/01");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Alma Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info2.nasl");
  script_require_keys("Host/OS/extended-third-party", "Host/local_checks_enabled", "Host/AlmaLinux/release", "Host/AlmaLinux/rpm-list", "Host/cpu");

  exit(0);
}
include('rpm2.inc');

var third_party_support = get_kb_item('Host/OS/extended-third-party');
if (empty_or_null(third_party_support) || third_party_support != 'TuxCare') exit(0, 'TuxCare support not enabled.');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_product = get_kb_item('installed_os/local/SSH/0/product');
if (isnull(os_product) || 'AlmaLinux' >!< os_product) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_version = get_kb_item('installed_os/local/SSH/0/version');
if (isnull(os_version)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
if (! preg(pattern:"^9.6([^0-9]|$)", string:os_version)) audit(AUDIT_OS_NOT, 'AlmaLinux 9.6', 'AlmaLinux ' + os_version);

if (!get_kb_item('Host/AlmaLinux/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) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'AlmaLinux', cpu);


var constraints = [
  {
    'release': '9',
    'sp': '6',
    'pkgs': [
      {'reference':'shim-x64-15.8-4.el9_3.tuxcare.3', 'sp':'6', 'cpu':'x86_64', 'el_string':'el9_3', 'rpm_spec_vers_cmp':TRUE}
    ]
  }
];

var os_release = get_one_kb_item('installed_os/local/SSH/0/release');
var os_sp = get_one_kb_item('Host/*/minor_release');

var flag = 0;
var reference;
var sp;
var _cpu;
var el_string;
var rpm_spec_vers_cmp;
var epoch;
var allowmaj;
var exists_check;
var cves;
foreach var constraint ( constraints ) {
  # Check that the target release is equal to the affected release
  if (!empty_or_null(constraint['release'])){
    if (constraint['release'] != os_release) continue;
  }
  if (!empty_or_null(constraint['sp'])){
    if (constraint['sp'] != os_sp) continue;
  }
  foreach var pkg ( constraint['pkgs'] ) {
    reference = NULL;
    sp = NULL;
    _cpu = NULL;
    el_string = NULL;
    rpm_spec_vers_cmp = NULL;
    epoch = NULL;
    allowmaj = NULL;
    exists_check = NULL;
    cves = NULL;
    if (!empty_or_null(pkg['reference'])) reference = pkg['reference'];
    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 &&
        ## (no known rpm to check OR known rpm_exists)
        (!exists_check || rpm_exists(rpm:exists_check)) &&
        rpm_check(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)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'shim-x64');
}