Vulnerabilities > CVE-2019-1754 - Improper Input Validation vulnerability in Cisco IOS XE

047910
CVSS 9.0 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
SINGLE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
network
low complexity
cisco
CWE-20
critical
nessus

Summary

A vulnerability in the authorization subsystem of Cisco IOS XE Software could allow an authenticated but unprivileged (level 1), remote attacker to run privileged Cisco IOS commands by using the web UI. The vulnerability is due to improper validation of user privileges of web UI users. An attacker could exploit this vulnerability by submitting a malicious payload to a specific endpoint in the web UI. A successful exploit could allow the lower-privileged attacker to execute arbitrary commands with higher privileges on the affected device.

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-IOSXE-PRIVESC.NASL
descriptionAccording to its self-reported version, Cisco IOS XE Software is affected by following vulnerability - A vulnerability in the authorization subsystem of Cisco IOS XE Software could allow an authenticated but unprivileged (level 1), remote attacker to run privileged Cisco IOS commands by using the web UI.The vulnerability is due to improper validation of user privileges of web UI users. An attacker could exploit this vulnerability by submitting a malicious payload to a specific endpoint in the web UI. A successful exploit could allow the lower-privileged attacker to execute arbitrary commands with higher privileges on the affected device. (CVE-2019-1754) Please see the included Cisco BIDs and Cisco Security Advisory for more information
last seen2020-06-01
modified2020-06-02
plugin id127917
published2019-08-20
reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/127917
titleCisco IOS XE Software Privilege Escalation Vulnerability
code
#TRUSTED 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
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(127917);
  script_version("1.4");
  script_cvs_date("Date: 2019/12/20");

  script_cve_id("CVE-2019-1754");
  script_xref(name:"CISCO-BUG-ID", value:"CSCvi36813");
  script_xref(name:"CISCO-SA", value:"cisco-sa-20190327-iosxe-privesc");

  script_name(english:"Cisco IOS XE Software Privilege Escalation Vulnerability");
  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 vulnerability

  - A vulnerability in the authorization subsystem of Cisco
    IOS XE Software could allow an authenticated but
    unprivileged (level 1), remote attacker to run
    privileged Cisco IOS commands by using the web UI.The
    vulnerability is due to improper validation of user
    privileges of web UI users. An attacker could exploit
    this vulnerability by submitting a malicious payload to
    a specific endpoint in the web UI. A successful exploit
    could allow the lower-privileged attacker to execute
    arbitrary commands with higher privileges on the
    affected device. (CVE-2019-1754)

Please see the included Cisco BIDs and Cisco Security Advisory for
more information");
  # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190327-iosxe-privesc
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?56dcafb4");
  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/CSCvi36813");
  script_set_attribute(attribute:"solution", value:
"Upgrade to the relevant fixed version referenced in Cisco bug ID
CSCvi36813");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:C/I:C/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:L/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-2019-1754");

  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:"2019/08/20");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xe");
  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_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",
  "16.9.1s",
  "16.9.1d",
  "16.9.1c",
  "16.9.1b",
  "16.8.2",
  "16.8.1s",
  "16.8.1e",
  "16.8.1d",
  "16.8.1c",
  "16.8.1b",
  "16.8.1a",
  "16.8.1",
  "16.7.1b",
  "16.7.1a",
  "16.7.1"
);

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


reporting = make_array(
'port'     , 0,
'severity' , SECURITY_HOLE,
'version'  , product_info['version'],
'bug_id'   , 'CSCvi36813'
);

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