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nessusThis script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.AL2_ALAS-2022-1745.NASL
HistoryJan 28, 2022 - 12:00 a.m.

Amazon Linux 2 : polkit (ALAS-2022-1745)

2022-01-2800:00:00
This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
136

The version of polkit installed on the remote host is prior to 0.112-26. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2022-1745 advisory.

  • A local privilege escalation vulnerability was found on polkit’s pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn’t handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it’ll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine. (CVE-2021-4034)

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

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2022-1745.
##

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

if (description)
{
  script_id(157182);
  script_version("1.11");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/01/16");

  script_cve_id("CVE-2021-4034");
  script_xref(name:"ALAS", value:"2022-1745");
  script_xref(name:"IAVA", value:"2022-A-0055");
  script_xref(name:"CISA-KNOWN-EXPLOITED", value:"2022/07/18");

  script_name(english:"Amazon Linux 2 : polkit (ALAS-2022-1745)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of polkit installed on the remote host is prior to 0.112-26. It is, therefore, affected by a vulnerability
as referenced in the ALAS2-2022-1745 advisory.

  - A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is
    a setuid tool designed to allow unprivileged users to run commands as privileged users according
    predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly
    and ends trying to execute environment variables as commands. An attacker can leverage this by crafting
    environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully
    executed the attack can cause a local privilege escalation given unprivileged users administrative rights
    on the target machine. (CVE-2021-4034)

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://alas.aws.amazon.com/AL2/ALAS-2022-1745.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2021-4034.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update polkit' to update your system.");
  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:H/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:H/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-4034");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"exploit_framework_core", value:"true");
  script_set_attribute(attribute:"exploited_by_malware", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Local Privilege Escalation in polkits pkexec');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");
  script_set_attribute(attribute:"exploit_framework_canvas", value:"true");
  script_set_attribute(attribute:"canvas_package", value:"CANVAS");

  script_set_attribute(attribute:"vuln_publication_date", value:"2022/01/25");
  script_set_attribute(attribute:"patch_publication_date", value:"2022/01/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2022/01/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:polkit");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:polkit-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:polkit-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:polkit-docs");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon 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/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var release = get_kb_item("Host/AmazonLinux/release");
if (isnull(release) || !strlen(release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
var os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'polkit-0.112-26.amzn2.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-0.112-26.amzn2.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-0.112-26.amzn2.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-debuginfo-0.112-26.amzn2.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-debuginfo-0.112-26.amzn2.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-debuginfo-0.112-26.amzn2.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-devel-0.112-26.amzn2.1', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-devel-0.112-26.amzn2.1', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-devel-0.112-26.amzn2.1', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'polkit-docs-0.112-26.amzn2.1', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var reference = NULL;
  var release = NULL;
  var cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var allowmaj = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = package_array['release'];
  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['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (reference && release) {
    if (rpm_check(release:release, cpu:cpu, reference:reference, 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, "polkit / polkit-debuginfo / polkit-devel / etc");
}