Amazon Linux AMI : amazon-ssm-agent (ALAS-2023-1866)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2023-1866.
##

include('compat.inc');

if (description)
{
  script_id(183853);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/31");

  script_cve_id(
    "CVE-2021-43565",
    "CVE-2022-41723",
    "CVE-2023-24538",
    "CVE-2023-24540"
  );
  script_xref(name:"IAVB", value:"2023-B-0012-S");
  script_xref(name:"IAVB", value:"2023-B-0022-S");

  script_name(english:"Amazon Linux AMI : amazon-ssm-agent (ALAS-2023-1866)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux AMI host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of amazon-ssm-agent installed on the remote host is prior to 3.2.1705.0-1. It is, therefore, affected by
multiple vulnerabilities as referenced in the ALAS-2023-1866 advisory.

  - The x/crypto/ssh package before 0.0.0-20211202192323-5770296d904e of golang.org/x/crypto allows an
    attacker to panic an SSH server. (CVE-2021-43565)

  - A maliciously crafted HTTP/2 stream could cause excessive CPU consumption in the HPACK decoder, sufficient
    to cause a denial of service from a small number of small requests. (CVE-2022-41723)

  - Templates do not properly consider backticks (`) as Javascript string delimiters, and do not escape them
    as expected. Backticks are used, since ES6, for JS template literals. If a template contains a Go template
    action within a Javascript template literal, the contents of the action can be used to terminate the
    literal, injecting arbitrary Javascript code into the Go template. As ES6 template literals are rather
    complex, and themselves can do string interpolation, the decision was made to simply disallow Go template
    actions from being used inside of them (e.g. var a = {{.}}), since there is no obviously safe way to
    allow this behavior. This takes the same approach as github.com/google/safehtml. With fix, Template.Parse
    returns an Error when it encounters templates like this, with an ErrorCode of value 12. This ErrorCode is
    currently unexported, but will be exported in the release of Go 1.21. Users who rely on the previous
    behavior can re-enable it using the GODEBUG flag jstmpllitinterp=1, with the caveat that backticks will
    now be escaped. This should be used with caution. (CVE-2023-24538)

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://alas.aws.amazon.com/ALAS-2023-1866.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2021-43565.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2022-41723.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-24538.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-24540.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update amazon-ssm-agent' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/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:N/AC:L/PR:N/UI:N/S:U/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-2023-24540");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2022/04/07");
  script_set_attribute(attribute:"patch_publication_date", value:"2023/10/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2023/10/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:amazon-ssm-agent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:amazon-ssm-agent-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  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) 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("rpm.inc");

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

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

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

var pkgs = [
    {'reference':'amazon-ssm-agent-3.2.1705.0-1.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'amazon-ssm-agent-debuginfo-3.2.1705.0-1.amzn1', 'cpu':'x86_64', 'release':'ALA', '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 = 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, "amazon-ssm-agent / amazon-ssm-agent-debuginfo");
}