Vulnerabilities > CVE-2019-1910 - Improper Input Validation vulnerability in Cisco IOS XR

047910
CVSS 7.4 - HIGH
Attack vector
ADJACENT_NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH
low complexity
cisco
CWE-20
nessus

Summary

A vulnerability in the implementation of the Intermediate System–to–Intermediate System (IS–IS) routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker who is in the same IS–IS area to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of crafted IS–IS link-state protocol data units (PDUs). An attacker could exploit this vulnerability by sending a crafted link-state PDU to an affected system to be processed. A successful exploit could allow the attacker to cause all routers within the IS–IS area to unexpectedly restart the IS–IS process, resulting in a DoS condition. This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco IOS XR Software earlier than Release 6.6.3 and are configured with the IS–IS routing protocol. Cisco has confirmed that this vulnerability affects both Cisco IOS XR 32-bit Software and Cisco IOS XR 64-bit Software.

Vulnerable Configurations

Part Description Count
OS
Cisco
233
Application
Cisco
1

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-20190807-IOSXR-ISIS-DOS-1918.NASL
descriptionAccording to its self-reported version, Cisco IOS XR Software is affected by multiple vulnerabilities: - A vulnerability in the implementation of the Intermediate System-to-Intermediate System (IS-IS) routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of crafted IS-IS link-state protocol data units (PDUs). An attacker could exploit this vulnerability by sending a crafted link-state PDU to an affected system to be processed. A successful exploit could allow the attacker to cause all routers within the IS-IS area to unexpectedly restart the IS-IS process, resulting in a DoS condition. This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco IOS XR Software earlier than Release 6.6.3 and are configured with the IS-IS routing protocol. Cisco has confirmed that this vulnerability affects both Cisco IOS XR 32-bit Software and Cisco IOS XR 64-bit Software. (CVE-2019-1910) - A vulnerability in the implementation of Intermediate System-to-Intermediate System (IS-IS) routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of IS-IS link-state protocol data units (PDUs). An attacker could exploit this vulnerability by sending specific link-state PDUs to an affected system to be processed. A successful exploit could allow the attacker to cause incorrect calculations used in the weighted remote shared risk link groups (SRLG) or in the IGP Flexible Algorithm. It could also cause tracebacks to the logs or potentially cause the receiving device to crash the IS-IS process, resulting in a DoS condition. (CVE-2019-1918) Please see the included Cisco BIDs and Cisco Security Advisory for more information
last seen2020-06-01
modified2020-06-02
plugin id127900
published2019-08-16
reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/127900
titleCisco IOS XR Software Intermediate System-to-Intermediate System Denial of Service Vulnerability
code
#TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(127900);
  script_version("1.7");
  script_cvs_date("Date: 2020/02/14");

  script_cve_id("CVE-2019-1910", "CVE-2019-1918");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvp49076");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvp90854");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190807-iosxr-isis-dos-1910");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190807-iosxr-isis-dos-1918");

  script_name(english:"Cisco IOS XR Software Intermediate System-to-Intermediate System Denial of Service Vulnerability");
  script_summary(english:"Checks the version of Cisco IOS XR 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 XR Software is affected by multiple vulnerabilities:

  - A vulnerability in the implementation of the Intermediate System-to-Intermediate System (IS-IS)
  routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker
  who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is
  due to incorrect processing of crafted IS-IS link-state protocol data units (PDUs).
  An attacker could exploit this vulnerability by sending a crafted link-state PDU to an affected
  system to be processed. A successful exploit could allow the attacker to cause all routers within
  the IS-IS area to unexpectedly restart the IS-IS process, resulting in a DoS condition. This
  vulnerability affects Cisco devices if they are running a vulnerable release of Cisco IOS XR
  Software earlier than Release 6.6.3 and are configured with the IS-IS routing protocol. Cisco has
  confirmed that this vulnerability affects both Cisco IOS XR 32-bit Software and Cisco IOS XR 64-bit
  Software. (CVE-2019-1910)

  - A vulnerability in the implementation of Intermediate System-to-Intermediate System (IS-IS)
  routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker
  who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is
  due to incorrect processing of IS-IS link-state protocol data units (PDUs).
  An attacker could exploit this vulnerability by sending specific link-state PDUs to an affected
  system to be processed. A successful exploit could allow the attacker to cause incorrect calculations
  used in the weighted remote shared risk link groups (SRLG) or in the IGP Flexible Algorithm. It
  could also cause tracebacks to the logs or potentially cause the receiving device to crash the IS-IS
  process, resulting in a DoS condition. (CVE-2019-1918)

Please see the included Cisco BIDs and Cisco Security Advisory for more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190807-iosxr-isis-dos-1910
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?6e181e06");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190807-iosxr-isis-dos-1918
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?9cf9e486");
  # https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvp49076
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?22433b62");
  # https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvp90854
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?ec503ab3");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug IDs CSCvp49076 and CSCvp90854");
  script_set_cvss_base_vector("CVSS2#AV:A/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:A/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-2019-1910");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/08/07");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/08/07");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/08/16");

  script_set_attribute(attribute:"potential_vulnerability", value:"true");
  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xr");
  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_xr_version.nasl");
  script_require_keys("Host/Cisco/IOS-XR/Version", "Settings/ParanoidReport");

  exit(0);
}

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

product_info = cisco::get_product_info(name:'Cisco IOS XR');
if (report_paranoia < 2) audit(AUDIT_PARANOID);

vuln_ranges = [
   {'min_ver' : '0.0',  'fix_ver' : '6.6.3'}
];

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

reporting = make_array(
'port'     , 0,
'severity' , SECURITY_WARNING,
'version'  , product_info['version'],
'bug_id'   , 'CSCvp49076 and CSCvp90854'
);

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