CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
81.5%
An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). The calculations performed by mbedtls_mpi_exp_mod are not limited; thus, supplying overly large parameters could lead to denial of service when generating Diffie- Hellman key pairs.
This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.
#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##
include('compat.inc');
if (description)
{
script_id(501676);
script_version("1.3");
script_set_attribute(attribute:"plugin_modification_date", value:"2024/09/04");
script_cve_id("CVE-2020-36475");
script_xref(name:"ICSA", value:"21-257-20");
script_name(english:"Siemens LOGO! CMR and SIMATIC RTU 3000 Incorrect Calculation of Buffer Size (CVE-2020-36475)");
script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
script_set_attribute(attribute:"description", value:
"An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9
LTS and before 2.7.18 LTS). The calculations performed by
mbedtls_mpi_exp_mod are not limited; thus, supplying overly large
parameters could lead to denial of service when generating Diffie-
Hellman key pairs.
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://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9");
script_set_attribute(attribute:"see_also", value:"https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0");
script_set_attribute(attribute:"see_also", value:"https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18");
script_set_attribute(attribute:"see_also", value:"https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf");
script_set_attribute(attribute:"see_also", value:"https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html");
script_set_attribute(attribute:"see_also", value:"https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html");
script_set_attribute(attribute:"see_also", value:"https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-20");
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.
For LOGO! CMR2020, Siemens recommends affected users update to v2.2 or later.
For LOGO! CMR2040, Siemens recommends affected users update to v2.2 or later.
For the SIMATIC RTU 3000 family, Siemens recommends affected users use the certificate projection feature to pin the
valid certificates of external servers providing services to the RTU/CMR devices. Refer to the product manual for
further information.");
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-2020-36475");
script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
script_set_attribute(attribute:"exploit_available", value:"false");
script_cwe_id(131);
script_set_attribute(attribute:"vuln_publication_date", value:"2021/08/23");
script_set_attribute(attribute:"patch_publication_date", value:"2021/08/23");
script_set_attribute(attribute:"plugin_publication_date", value:"2023/09/21");
script_set_attribute(attribute:"plugin_type", value:"remote");
script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:logo%21_cmr2020_firmware");
script_set_attribute(attribute:"cpe", value:"cpe:/o:siemens:logo%21_cmr2040_firmware");
script_set_attribute(attribute:"generated_plugin", value:"current");
script_end_attributes();
script_category(ACT_GATHER_INFO);
script_family(english:"Tenable.ot");
script_copyright(english:"This script is Copyright (C) 2023-2024 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:logo%21_cmr2020_firmware" :
{"versionEndExcluding" : "2.2", "family" : "LOGO!CM"},
"cpe:/o:siemens:logo%21_cmr2040_firmware" :
{"versionEndExcluding" : "2.2", "family" : "LOGO!CM"}
};
tenable_ot::cve::compare_and_report(asset:asset, cpes:vuln_cpes, severity:SECURITY_WARNING);
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-36475
cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf
github.com/ARMmbed/mbedtls/releases/tag/v2.16.9
github.com/ARMmbed/mbedtls/releases/tag/v2.25.0
github.com/ARMmbed/mbedtls/releases/tag/v2.7.18
lists.debian.org/debian-lts-announce/2021/11/msg00021.html
lists.debian.org/debian-lts-announce/2022/12/msg00036.html
www.cisa.gov/news-events/ics-advisories/icsa-21-257-20
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
81.5%