Vulnerabilities > CVE-2019-1706 - Use of a Broken or Risky Cryptographic Algorithm vulnerability in Cisco Adaptive Security Appliance Software

047910
CVSS 8.6 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH
network
low complexity
cisco
CWE-327
nessus

Summary

A vulnerability in the software cryptography module of the Cisco Adaptive Security Virtual Appliance (ASAv) and Firepower 2100 Series running Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause an unexpected reload of the device that results in a denial of service (DoS) condition. The vulnerability is due to a logic error with how the software cryptography module handles IPsec sessions. An attacker could exploit this vulnerability by creating and sending traffic in a high number of IPsec sessions through the targeted device. A successful exploit could cause the device to reload and result in a DoS condition.

Vulnerable Configurations

Part Description Count
OS
Cisco
26
Hardware
Cisco
8

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Encryption Brute Forcing
    An attacker, armed with the cipher text and the encryption algorithm used, performs an exhaustive (brute force) search on the key space to determine the key that decrypts the cipher text to obtain the plaintext.
  • Creating a Rogue Certificate Authority Certificate
    An attacker exploits a weakness in the MD5 hash algorithm (weak collision resistance) to generate a certificate signing request (CSR) that contains collision blocks in the "to be signed" part. The attacker specially crafts two different, but valid X.509 certificates that when hashed with the MD5 algorithm would yield the same value. The attacker then sends the CSR for one of the certificates to the Certification Authority which uses the MD5 hashing algorithm. That request is completely valid and the Certificate Authority issues an X.509 certificate to the attacker which is signed with its private key. An attacker then takes that signed blob and inserts it into another X.509 certificate that the attacker generated. Due to the MD5 collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the attackers' second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority. To make the attack more interesting, the second certificate could be not just a regular certificate, but rather itself a signing certificate. Thus the attacker is able to start their own Certification Authority that is anchored in its root of trust in the legitimate Certification Authority that has signed the attackers' first X.509 certificate. If the original Certificate Authority was accepted by default by browsers, so will now the Certificate Authority set up by the attacker and of course any certificates that it signs. So the attacker is now able to generate any SSL certificates to impersonate any web server, and the user's browser will not issue any warning to the victim. This can be used to compromise HTTPS communications and other types of systems where PKI and X.509 certificates may be used (e.g., VPN, IPSec) .
  • Signature Spoof
    An attacker generates a message or datablock that causes the recipient to believe that the message or datablock was generated and cryptographically signed by an authoritative or reputable source, misleading a victim or victim operating system into performing malicious actions.
  • Cryptanalysis
    Cryptanalysis is a process of finding weaknesses in cryptographic algorithms and using these weaknesses to decipher the ciphertext without knowing the secret key (instance deduction). Sometimes the weakness is not in the cryptographic algorithm itself, but rather in how it is applied that makes cryptanalysis successful. An attacker may have other goals as well, such as: 1. Total Break - Finding the secret key 2. Global Deduction - Finding a functionally equivalent algorithm for encryption and decryption that does not require knowledge of the secret key. 3. Information Deduction - Gaining some information about plaintexts or ciphertexts that was not previously known 4. Distinguishing Algorithm - The attacker has the ability to distinguish the output of the encryption (ciphertext) from a random permutation of bits The goal of the attacker performing cryptanalysis will depend on the specific needs of the attacker in a given attack context. In most cases, if cryptanalysis is successful at all, an attacker will not be able to go past being able to deduce some information about the plaintext (goal 3). However, that may be sufficient for an attacker, depending on the context.

Nessus

NASL familyCISCO
NASL idCISCO-SA-20190501-ASA-IPSEC-DOS.NASL
descriptionAccording to its self-reported version, the Cisco Adaptive Security Appliance (ASA) Software is affected by the following vulnerability : - A vulnerability in the software cryptography module of the Cisco Adaptive Security Virtual Appliance (ASAv) and Firepower 2100 Series running Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause an unexpected reload of the device that results in a denial of service (DoS) condition.The vulnerability is due to a logic error with how the software cryptography module handles IPsec sessions. An attacker could exploit this vulnerability by creating and sending traffic in a high number of IPsec sessions through the targeted device. A successful exploit could cause the device to reload and result in a DoS condition. (CVE-2019-1706) Please see the included Cisco BIDs and Cisco Security Advisory for more information
last seen2020-05-31
modified2020-05-25
plugin id136829
published2020-05-25
reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/136829
titleCisco Adaptive Security Appliance (AS IPsec Denial of Service Vulnerability
code
#
# (C) Tenable Network Security, Inc.
#

include('compat.inc');

if (description)
{
  script_id(136829);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/27");

  script_cve_id("CVE-2019-1706");
  script_bugtraq_id(108144);
  script_xref(name:"CISCO-BUG-ID", value:"CSCvk66732");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190501-asa-ipsec-dos");

  script_name(english:"Cisco Adaptive Security Appliance (AS IPsec Denial of Service Vulnerability");
  script_summary(english:"Checks the version of Cisco Adaptive Security Appliance (ASA) Software");

  script_set_attribute(attribute:"synopsis", value:
"The remote device is missing a vendor-supplied security patch");
  script_set_attribute(attribute:"description", value:
"According to its self-reported version, the Cisco Adaptive Security
Appliance (ASA) Software is affected by the following vulnerability :

  - A vulnerability in the software cryptography module of
    the Cisco Adaptive Security Virtual Appliance (ASAv) and
    Firepower 2100 Series running Cisco Adaptive Security
    Appliance (ASA) Software could allow an unauthenticated,
    remote attacker to cause an unexpected reload of the
    device that results in a denial of service (DoS)
    condition.The vulnerability is due to a logic error with
    how the software cryptography module handles IPsec
    sessions.  An attacker could exploit this vulnerability
    by creating and sending traffic in a high number of
    IPsec sessions through the targeted device. A successful
    exploit could cause the device to reload and result in a
    DoS condition. (CVE-2019-1706)

Please see the included Cisco BIDs and Cisco Security Advisory for
more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-asa-ipsec-dos
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?195b41d9");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvk66732");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCvk66732");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C");
  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-2019-1706");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_cwe_id(404);

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/05/01");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:adaptive_security_appliance");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"CISCO");

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "os_fingerprint.nasl");
  script_require_keys("Host/Cisco/ASA", "Host/Cisco/model");

  exit(0);
}

include('audit.inc');
include('cisco_workarounds.inc');
include('ccf.inc');

product_info = cisco::get_product_info(name:'Cisco Adaptive Security Appliance (ASA) Software');

if (
  product_info.model !~ '^21[0-9][0-9]($|[^0-9])' && # Firepower 2100 ASA
  product_info.model != 'v' # ASA
) audit(AUDIT_HOST_NOT, 'an affected Cisco ASA product');

vuln_ranges = [
  {'min_ver' : '9.9',  'fix_ver' : '9.9(2.50)'}
];

workarounds = make_list(CISCO_WORKAROUNDS['crypto_map']);

reporting = make_array(
  'port'     , 0,
  'severity' , SECURITY_HOLE,
  'version'  , product_info['version'],
  'bug_id'   , make_list('CSCvk66732')
);

cisco::check_and_report(
  product_info:product_info,
  workarounds:workarounds,
  reporting:reporting,
  vuln_ranges:vuln_ranges
);