Amazon Linux AMI : microcode_ctl (ALAS-2020-1396)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2020-1396.
#

include('compat.inc');

if (description)
{
  script_id(138638);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/12/11");

  script_cve_id("CVE-2020-0543", "CVE-2020-0548", "CVE-2020-0549");
  script_xref(name:"ALAS", value:"2020-1396");

  script_name(english:"Amazon Linux AMI : microcode_ctl (ALAS-2020-1396)");

  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 microcode_ctl installed on the remote host is prior to 2.1-47.39. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS-2020-1396 advisory.

    A new domain bypass transient execution attack known as Special Register Buffer Data Sampling (SRBDS) has
    been found. This flaw allows data values from special internal registers to be leaked by an attacker able
    to execute code on any core of the CPU. An unprivileged, local attacker can use this flaw to infer values
    returned by affected instructions known to be commonly used during cryptographic operations that rely on
    uniqueness, secrecy, or both. Incomplete cleanup from specific special register read operations in some
    Intel(R) Processors may allow an authenticated user to potentially enable information disclosure via local
    access. (CVE-2020-0543)

    Cleanup errors in some Intel(R) Processors may allow an authenticated user to potentially enable
    information disclosure via local access. (CVE-2020-0548)

    Cleanup errors in some data cache evictions for some Intel(R) Processors may allow an authenticated user
    to potentially enable information disclosure via local access. (CVE-2020-0549)

Tenable has extracted the preceding description block directly from the tested product security advisory.

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://access.redhat.com/security/cve/CVE-2020-0543");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/CVE-2020-0548");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/CVE-2020-0549");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/ALAS-2020-1396.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update microcode_ctl' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:P/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/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:N/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-0549");

  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:"2020/01/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/07/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/07/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:microcode_ctl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:microcode_ctl-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2020-2024 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':'microcode_ctl-2.1-47.39.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'microcode_ctl-2.1-47.39.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'microcode_ctl-debuginfo-2.1-47.39.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'microcode_ctl-debuginfo-2.1-47.39.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;
  var cves = 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 (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  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, cves:cves)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_NOTE,
      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, "microcode_ctl / microcode_ctl-debuginfo");
}