Cisco Nexus 9500 Series Switches Access Control List Bypass (CVE-2021-1591)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(501232);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/07/26");

  script_cve_id("CVE-2021-1591");

  script_name(english:"Cisco Nexus 9500 Series Switches Access Control List Bypass (CVE-2021-1591)");

  script_set_attribute(attribute:"synopsis", value:
"The remote OT asset is affected by a vulnerability.");
  script_set_attribute(attribute:"description", value:
"A vulnerability in the EtherChannel port subscription logic of Cisco
Nexus 9500 Series Switches could allow an unauthenticated, remote
attacker to bypass access control list (ACL) rules that are configured
on an affected device. This vulnerability is due to oversubscription
of resources that occurs when applying ACLs to port channel
interfaces. An attacker could exploit this vulnerability by attempting
to access network resources that are protected by the ACL. A
successful exploit could allow the attacker to access network
resources that would be protected by the ACL that was applied on the
port channel interface.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nexus-acl-vrvQYPVe
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6f91a2d7");
  script_set_attribute(attribute:"solution", value:
"Refer to the vendor advisory.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  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:L/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-1591");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/08/25");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/08/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2023/07/25");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:nx-os:9.3%284%29");
  script_set_attribute(attribute:"generated_plugin", value:"former");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}


include('tenable_ot_cve_funcs.inc');

get_kb_item_or_exit('Tenable.ot/Cisco');

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

var vuln_cpes = {
    "cpe:/o:cisco:nx-os:9.3%284%29" :
        {"versionEndIncluding" : "9.3%284%29", "versionStartIncluding" : "9.3%284%29", "family" : "NXOS"}
};

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