Ubuntu 20.04 LTS : Samba vulnerabilities (USN-5142-1)

##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-5142-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(155297);
  script_version("1.13");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/28");

  script_cve_id(
    "CVE-2016-2124",
    "CVE-2020-25717",
    "CVE-2020-25718",
    "CVE-2020-25719",
    "CVE-2020-25721",
    "CVE-2020-25722",
    "CVE-2021-3671",
    "CVE-2021-3738",
    "CVE-2021-23192"
  );
  script_xref(name:"USN", value:"5142-1");
  script_xref(name:"IAVA", value:"2021-A-0554-S");

  script_name(english:"Ubuntu 20.04 LTS : Samba vulnerabilities (USN-5142-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in
the USN-5142-1 advisory.

    Stefan Metzmacher discovered that Samba incorrectly handled SMB1 client connections. A remote attacker
    could possibly use this issue to downgrade connections to plaintext authentication. (CVE-2016-2124)

    Andrew Bartlett discovered that Samba incorrectly mapping domain users to local users. An authenticated
    attacker could possibly use this issue to become root on domain members. (CVE-2020-25717)

    Andrew Bartlett discovered that Samba did not correctly sandbox Kerberos tickets issues by an RODC. An
    RODC could print administrator tickets, contrary to expectations. (CVE-2020-25718)

    Andrew Bartlett discovered that Samba incorrectly handled Kerberos tickets. Delegated administrators could
    possibly use this issue to impersonate accounts, leading to total domain compromise. (CVE-2020-25719)

    Andrew Bartlett discovered that Samba did not provide stable AD identifiers to Kerberos acceptors.
    (CVE-2020-25721)

    Andrew Bartlett discovered that Samba did not properly check sensitive attributes. An authenticated
    attacker could possibly use this issue to escalate privileges. (CVE-2020-25722)

    Stefan Metzmacher discovered that Samba incorrectly handled certain large DCE/RPC requests. A remote
    attacker could possibly use this issue to bypass signature requirements. (CVE-2021-23192)

    William Ross discovered that Samba incorrectly handled memory. A remote attacker could use this issue to
    cause Samba to crash, resulting in a denial of service, or possibly escalate privileges. (CVE-2021-3738)

    Joseph Sutton discovered that Samba incorrectly handled certain TGS requests. An authenticated attacker
    could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2021-3671)

    The fix for CVE-2020-25717 results in possible behaviour changes that could affect certain environments.
    Please see the upstream advisory for more information:

    https://www.samba.org/samba/security/CVE-2020-25717.html

Tenable has extracted the preceding description block directly from the Ubuntu 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://ubuntu.com/security/notices/USN-5142-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/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: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-2020-25719");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2021-3738");

  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:"2021/10/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/11/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/11/12");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ctdb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libnss-winbind");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libpam-winbind");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsmbclient");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libsmbclient-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libwbclient-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libwbclient0");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-samba");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:registry-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-common-bin");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-dsdb-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-testsuite");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:samba-vfs-modules");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:smbclient");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:winbind");
  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:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) 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, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '20.04', 'pkgname': 'ctdb', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libnss-winbind', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libpam-winbind', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libsmbclient', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libsmbclient-dev', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libwbclient-dev', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'libwbclient0', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'python3-samba', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'registry-tools', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-common', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-common-bin', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-dev', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-dsdb-modules', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-libs', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-testsuite', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'samba-vfs-modules', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'smbclient', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'},
    {'osver': '20.04', 'pkgname': 'winbind', 'pkgver': '2:4.13.14+dfsg-0ubuntu0.20.04.1'}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'ctdb / libnss-winbind / libpam-winbind / libsmbclient / etc');
}