Puppet Unauthenticated Remote Code Execution

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#

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

if (description)
{
  script_id(70662);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/01/19");

  script_cve_id("CVE-2013-3567");
  script_bugtraq_id(60664);

  script_name(english:"Puppet Unauthenticated Remote Code Execution");
  script_summary(english:"Checks puppet version");

  script_set_attribute(
    attribute:"synopsis",
    value:
"A web application on the remote host has a code execution
vulnerability."
  );
  script_set_attribute(
    attribute:"description",
    value:
"According to its self-reported version number, the Puppet install on
the remote host has a remote code execution vulnerability. When making
REST API calls, the puppet master takes YAML from an untrusted client,
deserializes it, and then calls methods on the resulting object. A
YAML payload can be crafted to cause the deserialization to construct
an instance of any class available in the ruby process, which allows
an attacker to execute code contained in the payload."
  );
  script_set_attribute(attribute:"see_also", value:"https://puppet.com/security/cve/cve-2013-3567");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Puppet 2.7.22 / 3.2.2 or Puppet Enterprise 2.8.2 or
later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No exploit is required");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2013/06/18");
  script_set_attribute(attribute:"patch_publication_date", value:"2013/06/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2013/10/28");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:puppetlabs:puppet");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CGI abuses");

  script_copyright(english:"This script is Copyright (C) 2013-2021 Tenable Network Security, Inc.");

  script_dependencies("puppet_rest_detect.nasl");
  script_require_keys("puppet/rest_port");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("misc_func.inc");
include("http.inc");

##
# checks if the given version falls between the given bounds, and
# generates plugin output if it does
#
# @anonparam ver version to check
# @anonparam fix first fixed version
# @anonparam min_ver the lowest/earliest vulnerable version, relative to 'fix' (optional)
#
# @return plugin output if 'ver' is vulnerable relative to 'fix' and/or 'min_ver',
#         NULL otherwise
##
function _check_version(enterprise)
{
  local_var ver, fix, min_ver, major_ver, report;
  ver = _FCT_ANON_ARGS[0];
  fix = _FCT_ANON_ARGS[1];
  min_ver = _FCT_ANON_ARGS[2];

  if (
    # no lower bound
    (isnull(min_ver) &&
     ver_compare(ver:ver, fix:fix, strict:FALSE) < 0) ||

    # lower bound
    (!isnull(min_ver) &&
     ver_compare(ver:ver, fix:fix, strict:FALSE) < 0 &&
     ver_compare(ver:ver, fix:min_ver, strict:FALSE) >= 0)
  )
  {
    if (enterprise)
    {
      report =
        '\n  Installed version : Puppet Enterprise ' + ver +
        '\n  Fixed version     : Puppet Enterprise ' + fix + '\n';
    }
    else
    {
      report =
        '\n  Installed version : Puppet Open Source ' + ver +
        '\n  Fixed version     : Puppet Open Source ' + fix + '\n';
    }
  }
  else report = NULL;

  return report;
}

port = get_kb_item_or_exit('puppet/rest_port');
ver = get_kb_item_or_exit('puppet/' + port + '/version');
report = NULL;
vuln = FALSE;

if ('Enterprise' >< ver)
{
  # convert something like
  #   2.7.19 (Puppet Enterprise 2.7.0)
  # to
  #   2.7.0
  match = eregmatch(string:ver, pattern:"Enterprise ([0-9.]+)\)");
  if (isnull(match)) audit(AUDIT_UNKNOWN_WEB_APP_VER, 'Puppet Enterprise', build_url(port:port));
  ver = match[1];

  # Resolved in Puppet Enterprise 2.8.2
  if (report = _check_version(ver, '2.8.2', enterprise:TRUE)) vuln = TRUE;
}
else
{
  # Do not run against open source unless scan is paranoid
  if (report_paranoia < 2) audit(AUDIT_PARANOID);

  # sanity check - make sure the version doesn't include letters or anything else unexpected
  match = eregmatch(string:ver, pattern:"^([0-9.]+)$");
  if (isnull(match)) audit(AUDIT_NONNUMERIC_VER, 'Puppet', port, ver);
  ver = match[1];

  # Resolved in Puppet 2.7.22, 3.2.2
  if (
    (report = _check_version(ver, '2.7.22', '2.7')) ||
    (report = _check_version(ver, '3.2.2', '3.2'))
  ) vuln = TRUE;
}

if (!vuln) audit(AUDIT_LISTEN_NOT_VULN, 'Puppet', port, ver);

if (report_verbosity > 0) security_hole(port:port, extra:report);
else security_hole(port);