Siemens SIPROTEC 5 Improper Input Validation (CVE-2021-37206)

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

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

if (description)
{
  script_id(500582);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/03/04");

  script_cve_id("CVE-2021-37206");

  script_name(english:"Siemens SIPROTEC 5 Improper Input Validation (CVE-2021-37206)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5
relays with CPU variants CP100 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP300 (All versions < V8.80).
Received webpackets are not properly processed. An unauthenticated remote attacker with access to any of the Ethernet
interfaces could send specially crafted packets to force a restart of the target device.  

This plugin only works with
Tenable.ot. Please visit https://www.tenable.com/products/tenable-ot for more information.");
  script_set_attribute(attribute:"see_also", value:"https://cert-portal.siemens.com/productcert/pdf/ssa-500748.pdf");
  script_set_attribute(attribute:"see_also", value:"https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-16");
  script_set_attribute(attribute:"solution", value:
"The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original
can be found at CISA.gov.

Siemens recommends applying updates where available:

- SIPROTEC 5 relays with CPU variants CP050: Update to v8.80 or later version
- SIPROTEC 5 relays with CPU variants CP100: Update to v8.80 or later version
- SIPROTEC 5 relays with CPU variants CP300: Update to v8.80 or later version

For remaining products, Siemens has identified the following specific workaround and mitigation users can apply to
reduce the risk:

- Block access to Port 4443/TCP, such as with an external firewall.

Operators of critical power systems (e.g., TSOs or DSOs) worldwide are usually required by regulations to build
resilience into the power grids by applying multi-level redundant secondary protection schemes. Therefore, Siemens
recommends operators check whether appropriate resilient protection measures are in place. The risk of cyber incidents
impacting the grid’s reliability can thus be minimized by virtue of the grid design.

Siemens strongly recommends applying the provided security updates using the corresponding tooling and documented
procedures made available with the product. If supported by the product, an automated means to apply the security
updates across multiple product instances may be used. Siemens strongly recommends prior validation of any security
update before being applied, and supervision by trained staff of the update process in the target environment.

As a general security measure Siemens strongly recommends protecting network access with appropriate mechanisms (e.g.,
firewalls, segmentation, VPN). It is advised users configure the environment according to Siemens operational guidelines
for Digital Grid Products. in order to run the devices in a protected IT environment.

For additional information, please refer to Siemens Security Advisory SSA-500748");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  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:N/I:N/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-2021-37206");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(20);

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/09/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/09/14");
  script_set_attribute(attribute:"plugin_publication_date", value:"2022/02/07");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:siprotec_5_with_cpu_variant_cp050");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:siprotec_5_with_cpu_variant_cp100");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:siprotec_5_with_cpu_variant_cp300");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Tenable.ot");

  script_copyright(english:"This script is Copyright (C) 2022-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("tenable_ot_api_integration.nasl");
  script_require_keys("Tenable.ot/Siemens");

  exit(0);
}


include('tenable_ot_cve_funcs.inc');

get_kb_item_or_exit('Tenable.ot/Siemens');

var asset = tenable_ot::assets::get(vendor:'Siemens');

var vuln_cpes = {
    "cpe:/o:siemens:siprotec_5_with_cpu_variant_cp050" :
        {"versionEndExcluding" : "8.80", "family" : "Siprotec5"},
    "cpe:/o:siemens:siprotec_5_with_cpu_variant_cp100" :
        {"versionEndExcluding" : "8.80", "family" : "Siprotec5"},
    "cpe:/o:siemens:siprotec_5_with_cpu_variant_cp300" :
        {"versionEndExcluding" : "8.80", "family" : "Siprotec5"}
};

tenable_ot::cve::compare_and_report(asset:asset, cpes:vuln_cpes, severity:SECURITY_WARNING);