Vulnerabilities > CVE-2019-1738 - Improper Input Validation vulnerability in Cisco IOS and IOS XE

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH
network
low complexity
cisco
CWE-20
nessus
NVD
Published: 2019-03-28
Updated: 2024-11-21

Summary

A vulnerability in the Network-Based Application Recognition (NBAR) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability is due to a parsing issue on DNS packets. An attacker could exploit these vulnerabilities by sending crafted DNS packets through routers that are running an affected version and have NBAR enabled. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

Vulnerable Configurations

Part Description Count
OS
Cisco
164

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

Nessus

  • NASL familyCISCO
    NASL idCISCO-SA-20190327-NBAR.NASL
    descriptionAccording to its self-reported version, Cisco IOS XE Software is affected by following multiple vulnerabilities - Multiple vulnerabilities in the Network-Based Application Recognition (NBAR) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload.These vulnerabilities are due to a parsing issue on DNS packets. An attacker could exploit these vulnerabilities by sending crafted DNS packets through routers that are running an affected version and have NBAR enabled. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. (CVE-2019-1738, CVE-2019-1739, CVE-2019-1740) Please see the included Cisco BIDs and Cisco Security Advisory for more information
    last seen2020-05-09
    modified2019-04-05
    plugin id123794
    published2019-04-05
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/123794
    titleCisco IOS XE Software Network-Based Application Recognition Denial of Service Vulnerabilities
    code
    #TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(123794);
  script_version("1.8");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/08");

  script_cve_id("CVE-2019-1738", "CVE-2019-1739", "CVE-2019-1740");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvb51688");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvb51688");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvb51688");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190327-nbar");
  script_xref(name:"IAVA", value:"2019-A-0097-S");

  script_name(english:"Cisco IOS XE Software Network-Based Application Recognition Denial of Service Vulnerabilities");
  script_summary(english:"Checks the version of Cisco IOS XE 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 IOS XE Software is
affected by following multiple vulnerabilities

  - Multiple vulnerabilities in the Network-Based
    Application Recognition (NBAR) feature of Cisco IOS
    Software and Cisco IOS XE Software could allow an
    unauthenticated, remote attacker to cause an affected
    device to reload.These vulnerabilities are due to a
    parsing issue on DNS packets. An attacker could exploit
    these vulnerabilities by sending crafted DNS packets
    through routers that are running an affected version and
    have NBAR enabled. A successful exploit could allow the
    attacker to cause the affected device to reload,
    resulting in a denial of service (DoS) condition.
    (CVE-2019-1738, CVE-2019-1739, CVE-2019-1740)

Please see the included Cisco BIDs and Cisco Security Advisory for
more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190327-nbar
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7b838dda");
  script_set_attribute(attribute:"see_also", value:"http://tools.cisco.com/security/center/viewErp.x?alertId=ERP-71135");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb51688");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb51688");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb51688");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug IDs
CSCvb51688, CSCvb51688, CSCvb51688");
  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: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-2019-1738");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_cwe_id(20);

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/03/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/04/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xe");
  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) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("cisco_ios_xe_version.nasl");
  script_require_keys("Host/Cisco/IOS-XE/Version");

  exit(0);
}

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

product_info = cisco::get_product_info(name:'Cisco IOS XE Software');

version_list=make_list(
  '3.2.0JA',
  '3.18.4S',
  '3.18.3S',
  '3.18.2aSP',
  '3.18.2SP',
  '3.18.2S',
  '3.18.1iSP',
  '3.18.1hSP',
  '3.18.1gSP',
  '3.18.1cSP',
  '3.18.1bSP',
  '3.18.1aSP',
  '3.18.1SP',
  '3.18.1S',
  '3.18.0aS',
  '3.18.0SP',
  '3.18.0S',
  '3.17.4S',
  '3.17.3S',
  '3.17.2S ',
  '3.17.1aS',
  '3.17.1S',
  '3.17.0S',
  '3.16.5aS',
  '3.16.5S',
  '3.16.4gS',
  '3.16.4eS',
  '3.16.4dS',
  '3.16.4cS',
  '3.16.4bS',
  '3.16.4aS',
  '3.16.4S',
  '3.16.3aS',
  '3.16.3S',
  '3.16.2bS',
  '3.16.2aS',
  '3.16.2S',
  '3.16.1aS',
  '3.16.1S',
  '3.16.0cS',
  '3.16.0bS',
  '3.16.0aS',
  '3.16.0S',
  '16.5.1b',
  '16.5.1a',
  '16.5.1',
  '16.4.3',
  '16.4.2',
  '16.4.1',
  '16.3.4',
  '16.3.3',
  '16.3.2',
  '16.3.1a',
  '16.3.1',
  '16.2.2',
  '16.2.1'
);

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


reporting = make_array(
  'port'     , 0,
  'severity' , SECURITY_HOLE,
  'version'  , product_info['version'],
  'bug_id'   , 'CSCvb51688, CSCvb51688 and CSCvb51688',
  'cmds'     , make_list("show ip nbar control-plane | include NBAR state")
);

cisco::check_and_report(product_info:product_info, workarounds:workarounds, workaround_params:workaround_params, reporting:reporting, vuln_versions:version_list);
  • NASL familyCISCO
    NASL idCISCO-SA-20190327-IOS-NBAR.NASL
    descriptionAccording to its self-reported version, Cisco IOS Software is affected by following multiple vulnerabilities - Multiple vulnerabilities in the Network-Based Application Recognition (NBAR) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload.These vulnerabilities are due to a parsing issue on DNS packets. An attacker could exploit these vulnerabilities by sending crafted DNS packets through routers that are running an affected version and have NBAR enabled. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. (CVE-2019-1738, CVE-2019-1739, CVE-2019-1740) Please see the included Cisco BIDs and Cisco Security Advisory for more information
    last seen2020-03-26
    modified2020-03-19
    plugin id134713
    published2020-03-19
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/134713
    titleCisco IOS Software Network-Based Application Recognition Denial of Service Vulnerabilities
    code
    #TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include('compat.inc');

if (description)
{
  script_id(134713);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/24");

  script_cve_id("CVE-2019-1738", "CVE-2019-1739", "CVE-2019-1740");
  script_bugtraq_id(107597);
  script_xref(name:"CISCO-BUG-ID", value:"CSCvb51688");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvc94856");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvc99155");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvf01501");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190327-nbar");

  script_name(english:"Cisco IOS Software Network-Based Application Recognition Denial of Service Vulnerabilities");
  script_summary(english:"Checks the version of Cisco IOS 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 IOS Software is
affected by following multiple vulnerabilities

  - Multiple vulnerabilities in the Network-Based
    Application Recognition (NBAR) feature of Cisco IOS
    Software and Cisco IOS XE Software could allow an
    unauthenticated, remote attacker to cause an affected
    device to reload.These vulnerabilities are due to a
    parsing issue on DNS packets. An attacker could exploit
    these vulnerabilities by sending crafted DNS packets
    through routers that are running an affected version and
    have NBAR enabled. A successful exploit could allow the
    attacker to cause the affected device to reload,
    resulting in a denial of service (DoS) condition.
    (CVE-2019-1738, CVE-2019-1739, CVE-2019-1740)

Please see the included Cisco BIDs and Cisco Security Advisory for
more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190327-nbar
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?7b838dda");
  script_set_attribute(attribute:"see_also", value:"http://tools.cisco.com/security/center/viewErp.x?alertId=ERP-71135");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb51688");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvc94856");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvc99155");
  script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvf01501");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug IDs
CSCvb51688, CSCvc94856, CSCvc99155, CSCvf01501");
  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: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-2019-1738");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_cwe_id(20);

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/03/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/03/19");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xe");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios");
  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("cisco_ios_xe_version.nasl");
  script_require_keys("Host/Cisco/IOS-XE/Version");

  exit(0);
}

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

product_info = cisco::get_product_info(name:'Cisco IOS');

version_list=make_list(
  '15.5(3)S',
  '15.5(3)S1',
  '15.5(3)S1a',
  '15.5(3)S2',
  '15.5(3)S0a',
  '15.5(3)S3',
  '15.5(3)S4',
  '15.5(3)S5',
  '15.5(3)M',
  '15.5(3)M1',
  '15.5(3)M0a',
  '15.5(3)M2',
  '15.5(3)M2a',
  '15.5(3)M3',
  '15.5(3)M4',
  '15.5(3)M4a',
  '15.5(3)M5',
  '15.5(3)M4b',
  '15.5(3)M4c',
  '15.5(3)M5a',
  '15.5(3)SN0a',
  '15.5(3)SN',
  '15.6(1)S',
  '15.6(2)S',
  '15.6(2)S1',
  '15.6(1)S1',
  '15.6(1)S2',
  '15.6(2)S2',
  '15.6(1)S3',
  '15.6(2)S3',
  '15.6(1)S4',
  '15.6(2)S4',
  '15.6(1)T',
  '15.6(2)T',
  '15.6(1)T0a',
  '15.6(1)T1',
  '15.6(2)T1',
  '15.6(1)T2',
  '15.6(2)T0a',
  '15.6(2)T2',
  '15.3(3)JNP',
  '15.3(3)JNP1',
  '15.3(3)JNP3',
  '15.6(1)SN',
  '15.6(1)SN1',
  '15.6(2)SN',
  '15.6(1)SN2',
  '15.6(1)SN3',
  '15.6(3)SN',
  '15.6(4)SN',
  '15.6(5)SN',
  '15.6(6)SN',
  '15.6(7)SN',
  '15.6(7)SN1',
  '15.6(7)SN2',
  '15.3(3)JPB',
  '15.3(3)JPB1',
  '15.3(3)JD',
  '15.3(3)JD2',
  '15.3(3)JD3',
  '15.3(3)JD4',
  '15.3(3)JD5',
  '15.3(3)JD6',
  '15.3(3)JD7',
  '15.3(3)JD8',
  '15.3(3)JD9',
  '15.3(3)JD11',
  '15.3(3)JD12',
  '15.3(3)JD13',
  '15.3(3)JD14',
  '15.6(3)M',
  '15.6(3)M1',
  '15.6(3)M0a',
  '15.6(3)M1a',
  '15.6(3)M1b',
  '15.3(3)JPC',
  '15.3(3)JPC1',
  '15.3(3)JPC2',
  '15.3(3)JPC3',
  '15.3(3)JPC5',
  '15.3(3)JE',
  '15.3(3)JPD',
  '15.3(3)JF',
  '15.3(3)JF1',
  '15.3(3)JF2',
  '15.3(3)JF4',
  '15.3(3)JF5',
  '15.3(3)JG',
  '15.3(3)JG1',
  '15.3(3)JH',
  '15.3(3)JI',
  '15.3(3)JK2'
);

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

reporting = make_array(
  'port'     , 0,
  'severity' , SECURITY_HOLE,
  'version'  , product_info['version'],
  'bug_id'   , 'CSCvb51688, CSCvc94856,  CSCvc99155 and CSCvf01501',
  'cmds'     , make_list("show ip nbar control-plane | include NBAR state")
);

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

References