Cisco ASA Improper Enforcement of Message Integrity During Transmission in a Communication Channel (CVE-2021-34793)

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

include('compat.inc');

if (description)
{
  script_id(506146);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/10/07");

  script_cve_id("CVE-2021-34793");

  script_name(english:"Cisco ASA Improper Enforcement of Message Integrity During Transmission in a Communication Channel (CVE-2021-34793)");

  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 TCP Normalizer of Cisco Adaptive Security
Appliance (ASA) Software and Firepower Threat Defense (FTD) Software
operating in transparent mode could allow an unauthenticated, remote
attacker to poison MAC address tables, resulting in a denial of
service (DoS) vulnerability. This vulnerability is due to incorrect
handling of certain TCP segments when the affected device is operating
in transparent mode. An attacker could exploit this vulnerability by
sending a crafted TCP segment through an affected device. A successful
exploit could allow the attacker to poison the MAC address tables in
adjacent devices, resulting in network disruption.

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-asa-ftd-dos-JxYWMJyL
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?e81ea8c8");
  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: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:C/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-2021-34793");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");
  script_cwe_id(924);

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/10/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/10/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/10/06");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:adaptive_security_appliance_software:9");
  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) 2026 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:adaptive_security_appliance_software:9.9.0" :
        {"versionEndExcluding" : "9.12.4.29", "versionStartIncluding" : "9.9.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.13.0" :
        {"versionEndExcluding" : "9.14.3.9", "versionStartIncluding" : "9.13.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.15.0" :
        {"versionEndExcluding" : "9.15.1.17", "versionStartIncluding" : "9.15.0", "family" : "CiscoFirepower"},
    "cpe:/o:cisco:adaptive_security_appliance_software:9.16.0" :
        {"versionEndExcluding" : "9.16.2.3", "versionStartIncluding" : "9.16.0", "family" : "CiscoFirepower"}
};

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