Vulnerabilities > CVE-2019-1731 - Improper Handling of Exceptional Conditions vulnerability in Cisco Nx-Os

047910
CVSS 4.4 - MEDIUM
Attack vector
LOCAL
Attack complexity
LOW
Privileges required
HIGH
Confidentiality impact
HIGH
Integrity impact
NONE
Availability impact
NONE
local
low complexity
cisco
CWE-755
nessus
NVD
Published: 2019-05-15
Updated: 2020-10-09

Summary

A vulnerability in the SSH CLI key management functionality of Cisco NX-OS Software could allow an authenticated, local attacker to expose a user's private SSH key to all authenticated users on the targeted device. The attacker must authenticate with valid administrator device credentials. The vulnerability is due to incomplete error handling if a specific error type occurs during the SSH key export. An attacker could exploit this vulnerability by authenticating to the device and entering a crafted command at the CLI. A successful exploit could allow the attacker to expose a user's private SSH key. In addition, a similar type of error in the SSH key import could cause the passphrase-protected private SSH key to be imported unintentionally.

Vulnerable Configurations

Part Description Count
OS
Cisco
656
Hardware
Cisco
75

Common Weakness Enumeration (CWE)

Nessus

NASL familyCISCO
NASL idCISCO-SA-20190515-NXOS-SSH-INFO.NASL
descriptionAccording to its self-reported version, Cisco NX-OS Software is affected by an information disclosure vulnerability in the SSH CLI key management functionality which could allow an authenticated, local attacker to expose a user
last seen2020-06-01
modified2020-06-02
plugin id126344
published2019-06-28
reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/126344
titleCisco NX-OS Software SSH Key Information Disclosure Vulnerability
code
#TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(126344);
  script_version("1.5");
  script_cvs_date("Date: 2019/12/20");

  script_cve_id("CVE-2019-1731");
  script_bugtraq_id(108353);
  script_xref(name:"IAVA", value:"2019-A-0173");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvh76123");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvj01385");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvj01393");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvj01386");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190515-nxos-ssh-info");

  script_name(english:"Cisco NX-OS Software SSH Key Information Disclosure Vulnerability");
  script_summary(english:"Checks the version of Cisco NX-OS 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, Cisco NX-OS Software is
affected by an information disclosure vulnerability in the SSH CLI 
key management functionality which could allow an authenticated,
local attacker to expose a user's private SSH key to all authenticated
users on the targeted device. The attacker must authenticate with valid
administrator device credentials.

Please see the included Cisco BIDs and Cisco Security Advisory for
more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-nxos-ssh-info
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?8f6c2fad");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvh76123");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvj01385");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvj01393");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvj01386");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bugs ID
CSCvh76123, CSCvj01385, CSCvj01393, CSCvj01386");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:P/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/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-2019-1731");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_cwe_id(200);

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/05/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/06/28");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:nx-os");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("cisco_nxos_version.nasl");
  script_require_keys("Host/Cisco/NX-OS/Version", "Host/Cisco/NX-OS/Model", "Host/Cisco/NX-OS/Device");

  exit(0);
}

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

product_info = cisco::get_product_info(name:'Cisco NX-OS Software');


if ('Nexus' >< product_info['device'])
{
  if (product_info['model'] =~ '^30[0-9][0-9]' || product_info['model'] =~ '^90[0-9][0-9]') bugIDs = 'CSCvh76123';
  else if (product_info['model'] =~ '^35[0-9][0-9]') bugIDs = 'CSCvj01385';
  else if (product_info['model'] =~ '^36[0-9][0-9]' || product_info['model'] =~ '^95[0-9][0-9]') bugIDs = 'CSCvj01393';
}

if (isnull(bugIDs)) audit(AUDIT_HOST_NOT, 'affected');

version_list=make_list(
  '7.0(3)I7(5a)',
  '7.0(3)I7(5)',
  '7.0(3)I7(3)',
  '7.0(3)I7(2)',
  '7.0(3)I7(1)',
  '7.0(3)I6(2)',
  '7.0(3)I6(1)',
  '7.0(3)I5(2)',
  '7.0(3)I5(1)',
  '7.0(3)I4(8z)',
  '7.0(3)I4(8b)',
  '7.0(3)I4(8a)',
  '7.0(3)I4(8)',
  '7.0(3)I4(7)',
  '7.0(3)I4(6)',
  '7.0(3)I4(5)',
  '7.0(3)I4(4)',
  '7.0(3)I4(3)',
  '7.0(3)I4(2)',
  '7.0(3)I4(1)',
  '7.0(3)I3(1)',
  '7.0(3)I2(5)',
  '7.0(3)I2(4)',
  '7.0(3)I2(3)',
  '7.0(3)I2(2e)',
  '7.0(3)I2(2d)',
  '7.0(3)I2(2c)',
  '7.0(3)I2(2b)',
  '7.0(3)I2(2a)',
  '7.0(3)I2(2)',
  '7.0(3)I2(1a)',
  '7.0(3)I2(1)',
  '7.0(3)I1(3b)',
  '7.0(3)I1(3a)',
  '7.0(3)I1(3)',
  '7.0(3)I1(2)',
  '7.0(3)I1(1b)',
  '7.0(3)I1(1a)',
  '7.0(3)I1(1)',
  '7.0(3)F3(4)',
  '7.0(3)F3(3c)',
  '7.0(3)F3(3b)',
  '7.0(3)F3(3a)',
  '7.0(3)F3(3)',
  '7.0(3)F3(2)',
  '7.0(3)F3(1)',
  '7.0(3)F2(2)',
  '7.0(3)F2(1)',
  '7.0(3)F1(1)',
  '7.0(3)',
  '7.0(2)N1(1a)',
  '7.0(2)N1(1)',
  '7.0(2)I2(2c)',
  '7.0(1)N1(3)',
  '7.0(1)N1(1)',
  '7.0(0)N1(1)',
  '6.0(2)A8(9)',
  '6.0(2)A8(8)',
  '6.0(2)A8(7b)',
  '6.0(2)A8(7a)',
  '6.0(2)A8(7)',
  '6.0(2)A8(6)',
  '6.0(2)A8(5)',
  '6.0(2)A8(4a)',
  '6.0(2)A8(4)',
  '6.0(2)A8(3)',
  '6.0(2)A8(2)',
  '6.0(2)A8(1)',
  '6.0(2)A7(2a)',
  '6.0(2)A7(2)',
  '6.0(2)A7(1a)',
  '6.0(2)A7(1)',
  '6.0(2)A6(8)',
  '6.0(2)A6(7)',
  '6.0(2)A6(6)',
  '6.0(2)A6(5b)',
  '6.0(2)A6(5a)',
  '6.0(2)A6(5)',
  '6.0(2)A6(4a)',
  '6.0(2)A6(4)',
  '6.0(2)A6(3a)',
  '6.0(2)A6(3)',
  '6.0(2)A6(2a)',
  '6.0(2)A6(2)',
  '6.0(2)A6(1a)',
  '6.0(2)A6(1)',
  '6.0(2)A4(6)',
  '6.0(2)A4(5)',
  '6.0(2)A4(4)',
  '6.0(2)A4(3)',
  '6.0(2)A4(2)',
  '6.0(2)A4(1)',
  '6.0(2)A3(4)',
  '6.0(2)A3(2)',
  '6.0(2)A3(1)',
  '6.0(2)A1(2d)',
  '6.0(2)A1(1f)',
  '6.0(2)A1(1e)',
  '6.0(2)A1(1d)',
  '6.0(2)A1(1c)',
  '6.0(2)A1(1b)',
  '6.0(2)A1(1a)',
  '6.0(2)A1(1)'
);

workarounds = make_list(CISCO_WORKAROUNDS['no_workaround']);
workaround_params = make_list();

reporting = make_array(
  'port'     , 0,
  'severity' , SECURITY_NOTE,
  'version'  , product_info['version'],
  'bug_id'   , bugIDs
);

cisco::check_and_report(product_info:product_info, workarounds:workarounds, workaround_params:workaround_params, reporting:reporting, vuln_versions:version_list);

References