Vulnerabilities > CVE-2019-1936 - Improper Input Validation vulnerability in Cisco products
Attack vector
NETWORK Attack complexity
LOW Privileges required
HIGH Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
A vulnerability in the web-based management interface of Cisco Integrated Management Controller (IMC) Supervisor, Cisco UCS Director, and Cisco UCS Director Express for Big Data could allow an authenticated, remote attacker to execute arbitrary commands on the underlying Linux shell as the root user. Exploitation of this vulnerability requires privileged access to an affected device. The vulnerability is due to insufficient validation of user-supplied input by the web-based management interface. An attacker could exploit this vulnerability by logging in to the web-based management interface with administrator privileges and then sending a malicious request to a certain part of the interface.
Vulnerable Configurations
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.
Metasploit
| description | The Cisco UCS Director virtual appliance contains two flaws that can be combined and abused by an attacker to achieve remote code execution as root. The first one, CVE-2019-1937, is an authentication bypass, that allows the attacker to authenticate as an administrator. The second one, CVE-2019-1936, is a command injection in a password change form, that allows the attacker to inject commands that will execute as root. This module combines both vulnerabilities to achieve the unauthenticated command injection as root. It has been tested with Cisco UCS Director virtual machines 6.6.0 and 6.7.0. Note that Cisco also mentions in their advisory that their IMC Supervisor and UCS Director Express are also affected by these vulnerabilities, but this module was not tested with those products. |
| id | MSF:EXPLOIT/LINUX/HTTP/CISCO_UCS_RCE |
| last seen | 2020-06-14 |
| modified | 2019-08-29 |
| published | 2019-08-28 |
| references |
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| reporter | Rapid7 |
| source | https://github.com/rapid7/metasploit-framework/blob/master//modules/exploits/linux/http/cisco_ucs_rce.rb |
| title | Cisco UCS Director Unauthenticated Remote Code Execution |
Nessus
| NASL family | CISCO |
| NASL id | CISCO-SA-20190821-IMCS-UCS-CMDINJ.NASL |
| description | According to its self-reported version, the remote host is running a version of Cisco UCS Director that is affected by a command execution vulnerability. An authenticated, remote attacker can exploit this to execute arbitrary commands as a root user. |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 129291 |
| published | 2019-09-24 |
| reporter | This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/129291 |
| title | Cisco UCS Director Authentication Bypass (cisco-sa-20190821-imcs-ucs-cmdinj) |
| code | |
Packetstorm
data source https://packetstormsecurity.com/files/download/154308/cisco_ucs_rce.rb.txt id PACKETSTORM:154308 last seen 2019-09-02 published 2019-09-02 reporter Pedro Ribeiro source https://packetstormsecurity.com/files/154308/Cisco-UCS-Director-Unauthenticated-Remote-Code-Execution.html title Cisco UCS Director Unauthenticated Remote Code Execution data source https://packetstormsecurity.com/files/download/154239/ciscoucsimc-bypassexec.txt id PACKETSTORM:154239 last seen 2019-08-29 published 2019-08-28 reporter Pedro Ribeiro source https://packetstormsecurity.com/files/154239/Cisco-UCS-IMC-Supervisor-Authentication-Bypass-Command-Injection.html title Cisco UCS / IMC Supervisor Authentication Bypass / Command Injection
References
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190821-imcs-ucs-cmdinj
- https://seclists.org/bugtraq/2019/Aug/49
- http://packetstormsecurity.com/files/154239/Cisco-UCS-IMC-Supervisor-Authentication-Bypass-Command-Injection.html
- http://seclists.org/fulldisclosure/2019/Aug/36
- http://packetstormsecurity.com/files/154308/Cisco-UCS-Director-Unauthenticated-Remote-Code-Execution.html