Vulnerabilities > CVE-2019-20044 - Improper Check for Dropped Privileges vulnerability in multiple products

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Gentoo Linux Security Advisory GLSA 202003-55.
#
# The advisory text is Copyright (C) 2001-2020 Gentoo Foundation, Inc.
# and licensed under the Creative Commons - Attribution / Share Alike 
# license. See http://creativecommons.org/licenses/by-sa/3.0/
#

include("compat.inc");

if (description)
{
  script_id(134930);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/30");

  script_cve_id("CVE-2019-20044");
  script_xref(name:"GLSA", value:"202003-55");

  script_name(english:"GLSA-202003-55 : Zsh: Privilege escalation");
  script_summary(english:"Checks for updated package(s) in /var/db/pkg");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Gentoo host is missing one or more security-related
patches."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"The remote host is affected by the vulnerability described in GLSA-202003-55
(Zsh: Privilege escalation)

    It was discovered that Zsh was insecure dropping privileges when
      unsetting PRIVILEGED option.
  
Impact :

    An attacker could escalate privileges.
  
Workaround :

    There is no known workaround at this time."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security.gentoo.org/glsa/202003-55"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"All Zsh users should upgrade to the latest version:
      # emerge --sync
      # emerge --ask --oneshot --verbose '>=app-shells/zsh-5.8'"
  );
  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:L/AC:L/PR:L/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:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:gentoo:linux:zsh");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:gentoo:linux");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/02/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/03/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/03/26");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Gentoo Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Gentoo/release", "Host/Gentoo/qpkg-list");

  exit(0);
}


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

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Gentoo/release")) audit(AUDIT_OS_NOT, "Gentoo");
if (!get_kb_item("Host/Gentoo/qpkg-list")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;

if (qpkg_check(package:"app-shells/zsh", unaffected:make_list("ge 5.8"), vulnerable:make_list("lt 5.8"))) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:qpkg_report_get());
  else security_hole(0);
  exit(0);
}
else
{
  tested = qpkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "Zsh");
}

#
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were
# extracted from Red Hat Security Advisory RHSA-2020:0978. The text
# itself is copyright (C) Red Hat, Inc.
#


include('compat.inc');

if (description)
{
  script_id(134939);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/04/21");

  script_cve_id("CVE-2019-20044");
  script_xref(name:"RHSA", value:"2020:0978");

  script_name(english:"RHEL 8 : zsh (RHSA-2020:0978)");
  script_summary(english:"Checks the rpm output for the updated packages");

  script_set_attribute(attribute:"synopsis", value:
"The remote Red Hat host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in
the RHSA-2020:0978 advisory.

  - zsh: insecure dropping of privileges when unsetting
    PRIVILEGED option (CVE-2019-20044)

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://cwe.mitre.org/data/definitions/271.html");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/errata/RHSA-2020:0978");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/CVE-2019-20044");
  script_set_attribute(attribute:"solution", value:
"Update the affected zsh, zsh-debugsource and / or zsh-html packages.");
  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:L/AC:L/PR:L/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-2019-20044");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_cwe_id(271);

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/02/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/03/26");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/03/26");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:redhat:rhel_e4s:8.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:redhat:rhel_e4s:8.0::appstream");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:rhel_e4s:8.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:rhel_e4s:8.0::baseos");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:zsh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:zsh-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:zsh-html");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Red Hat Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/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);
release = get_kb_item('Host/RedHat/release');
if (isnull(release) || 'Red Hat' >!< release) audit(AUDIT_OS_NOT, 'Red Hat');
os_ver = pregmatch(pattern: "Red Hat Enterprise Linux.*release ([0-9]+(\.[0-9]+)?)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, 'Red Hat');
os_ver = os_ver[1];
if (! preg(pattern:"^8([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, 'Red Hat 8.x', 'Red Hat ' + os_ver);

if (!get_kb_item('Host/RedHat/rpm-list')) audit(AUDIT_PACKAGE_LIST_MISSING);

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, 'Red Hat', cpu);

pkgs = [
    {'reference':'zsh-5.5.1-6.el8_0.2', 'cpu':'aarch64', 'release':'8'},
    {'reference':'zsh-5.5.1-6.el8_0.2', 'cpu':'s390x', 'release':'8'},
    {'reference':'zsh-5.5.1-6.el8_0.2', 'cpu':'x86_64', 'release':'8'},
    {'reference':'zsh-debugsource-5.5.1-6.el8_0.2', 'cpu':'aarch64', 'release':'8'},
    {'reference':'zsh-debugsource-5.5.1-6.el8_0.2', 'cpu':'s390x', 'release':'8'},
    {'reference':'zsh-debugsource-5.5.1-6.el8_0.2', 'cpu':'x86_64', 'release':'8'},
    {'reference':'zsh-html-5.5.1-6.el8_0.2', 'release':'8'}
];

flag = 0;
foreach package_array ( pkgs ) {
  reference = NULL;
  release = NULL;
  sp = NULL;
  cpu = NULL;
  el_string = NULL;
  rpm_spec_vers_cmp = NULL;
  epoch = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) release = 'RHEL' + 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 (reference && release) {
    if (rpm_spec_vers_cmp) {
      if (rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:TRUE)) flag++;
    }
    else
    {
      if (rpm_check(release:release, sp:sp, cpu:cpu, reference:reference, epoch:epoch)) flag++;
    }
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get() + redhat_report_package_caveat()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'zsh / zsh-debugsource / zsh-html');
}