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This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.ALMA_LINUX_ALSA-2021-2569.NASL
HistoryFeb 09, 2022 - 12:00 a.m.

AlmaLinux 8 : libxml2 (ALSA-2021:2569)

2022-02-0900:00:00
This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
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74

7.9 High

AI Score

Confidence

High

The remote AlmaLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALSA-2021:2569 advisory.

  • Thereโ€™s a flaw in libxml2โ€™s xmllint in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by xmllint could trigger a use-after-free. The greatest impact of this flaw is to confidentiality, integrity, and availability. (CVE-2021-3516)

  • There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application. (CVE-2021-3517)

  • Thereโ€™s a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability. (CVE-2021-3518)

  • A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used to crash the application. The highest threat from this vulnerability is to system availability. (CVE-2021-3537)

  • A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing protection mechanisms and leading to denial of service. (CVE-2021-3541)

Note that Nessus has not tested for this issue but has instead relied only on the applicationโ€™s self-reported version number.

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The package checks in this plugin were extracted from
# AlmaLinux Security Advisory ALSA-2021:2569.
##

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

if (description)
{
  script_id(157541);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/11/13");

  script_cve_id(
    "CVE-2021-3516",
    "CVE-2021-3517",
    "CVE-2021-3518",
    "CVE-2021-3537",
    "CVE-2021-3541"
  );
  script_xref(name:"ALSA", value:"2021:2569");
  script_xref(name:"IAVA", value:"2021-A-0482");
  script_xref(name:"IAVA", value:"2021-A-0487-S");

  script_name(english:"AlmaLinux 8 : libxml2 (ALSA-2021:2569)");

  script_set_attribute(attribute:"synopsis", value:
"The remote AlmaLinux host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote AlmaLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the
ALSA-2021:2569 advisory.

  - There's a flaw in libxml2's xmllint in versions before 2.9.11. An attacker who is able to submit a crafted
    file to be processed by xmllint could trigger a use-after-free. The greatest impact of this flaw is to
    confidentiality, integrity, and availability. (CVE-2021-3516)

  - There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker
    who is able to supply a crafted file to be processed by an application linked with the affected
    functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to
    application availability, with some potential impact to confidentiality and integrity if an attacker is
    able to use memory information to further exploit the application. (CVE-2021-3517)

  - There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to
    be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact
    from this flaw is to confidentiality, integrity, and availability. (CVE-2021-3518)

  - A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while
    parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery
    mode and post-validated, the flaw could be used to crash the application. The highest threat from this
    vulnerability is to system availability. (CVE-2021-3537)

  - A flaw was found in libxml2. Exponential entity expansion attack its possible bypassing all existing
    protection mechanisms and leading to denial of service. (CVE-2021-3541)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://errata.almalinux.org/8/ALSA-2021-2569.html");
  script_set_attribute(attribute:"solution", value:
"Update the affected libxml2, libxml2-devel and / or python3-libxml2 packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:F/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:F/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-3517");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2021-3518");

  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:"2021/05/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/06/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2022/02/09");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:libxml2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:libxml2-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:alma:linux:python3-libxml2");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:alma:linux:8");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}


include('audit.inc');
include('global_settings.inc');
include('misc_func.inc');
include('rpm.inc');

if (!get_kb_item('Host/local_checks_enabled')) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var release = get_kb_item('Host/AlmaLinux/release');
if (isnull(release) || 'AlmaLinux' >!< release) audit(AUDIT_OS_NOT, 'AlmaLinux');
var os_ver = pregmatch(pattern: "AlmaLinux release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'AlmaLinux');
var os_ver = os_ver[1];
if (! preg(pattern:"^8([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'AlmaLinux 8.x', 'AlmaLinux ' + os_ver);

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 && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'AlmaLinux', cpu);

var pkgs = [
    {'reference':'libxml2-2.9.7-9.el8_4.2', 'cpu':'i686', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-2.9.7-9.el8_4.2', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-devel-2.9.7-9.el8_4.2', 'cpu':'i686', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'libxml2-devel-2.9.7-9.el8_4.2', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'python3-libxml2-2.9.7-9.el8_4.2', 'cpu':'x86_64', 'release':'8', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_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;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = 'Alma-' + package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (reference && release && (!exists_check || rpm_exists(release:release, rpm:exists_check))) {
    if (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)) 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, 'libxml2 / libxml2-devel / python3-libxml2');
}
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7.9 High

AI Score

Confidence

High

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