Vulnerabilities > CVE-2019-1803 - Incorrect Permission Assignment for Critical Resource vulnerability in Cisco Nexus 9000 Series Application Centric Infrastructure
Attack vector
LOCAL Attack complexity
LOW Privileges required
HIGH Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
A vulnerability in the filesystem management for the Cisco Nexus 9000 Series Application Centric Infrastructure (ACI) Mode Switch Software could allow an authenticated, local attacker with administrator rights to gain elevated privileges as the root user on an affected device. The vulnerability is due to overly permissive file permissions of specific system files. An attacker could exploit this vulnerability by authenticating to an affected device, creating a crafted command string, and writing this crafted string to a specific file location. A successful exploit could allow the attacker to execute arbitrary operating system commands as root on an affected device. The attacker would need to have valid administrator credentials for the device.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Accessing Functionality Not Properly Constrained by ACLs In applications, particularly web applications, access to functionality is mitigated by the authorization framework, whose job it is to map ACLs to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application or can run queries for data that he is otherwise not supposed to.
- Privilege Abuse An adversary is able to exploit features of the target that should be reserved for privileged users or administrators but are exposed to use by lower or non-privileged accounts. Access to sensitive information and functionality must be controlled to ensure that only authorized users are able to access these resources. If access control mechanisms are absent or misconfigured, a user may be able to access resources that are intended only for higher level users. An adversary may be able to exploit this to utilize a less trusted account to gain information and perform activities reserved for more trusted accounts. This attack differs from privilege escalation and other privilege stealing attacks in that the adversary never actually escalates their privileges but instead is able to use a lesser degree of privilege to access resources that should be (but are not) reserved for higher privilege accounts. Likewise, the adversary does not exploit trust or subvert systems - all control functionality is working as configured but the configuration does not adequately protect sensitive resources at an appropriate level.
- Directory Indexing An adversary crafts a request to a target that results in the target listing/indexing the content of a directory as output. One common method of triggering directory contents as output is to construct a request containing a path that terminates in a directory name rather than a file name since many applications are configured to provide a list of the directory's contents when such a request is received. An adversary can use this to explore the directory tree on a target as well as learn the names of files. This can often end up revealing test files, backup files, temporary files, hidden files, configuration files, user accounts, script contents, as well as naming conventions, all of which can be used by an attacker to mount additional attacks.
- Accessing, Modifying or Executing Executable Files An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
- Exploiting Incorrectly Configured Access Control Security Levels An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack. Most commonly, attackers would take advantage of controls that provided too little protection for sensitive activities in order to perform actions that should be denied to them. In some circumstances, an attacker may be able to take advantage of overly restrictive access control policies, initiating denial of services (if an application locks because it unexpectedly failed to be granted access) or causing other legitimate actions to fail due to security. The latter class of attacks, however, is usually less severe and easier to detect than attacks based on inadequate security restrictions. This attack pattern differs from CAPEC 1, "Accessing Functionality Not Properly Constrained by ACLs" in that the latter describes attacks where sensitive functionality lacks access controls, where, in this pattern, the access control is present, but incorrectly configured.
Nessus
| NASL family | CISCO |
| NASL id | CISCO-SA-20190501-NEXUS9K-RPE.NASL |
| description | According to its self-reported version, Cisco NX-OS System Software in ACI Mode is affected by an elevation of privilege vulnerability exists in the filesystem management due to improper file permissions. An authenticated, local attacker can exploit this, via a crafted command, to gain root privileges. Please see the included Cisco BIDs and Cisco Security Advisory for more information. |
| last seen | 2020-06-10 |
| modified | 2020-06-03 |
| plugin id | 137074 |
| published | 2020-06-03 |
| reporter | This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/137074 |
| title | Cisco Nexus 9000 Series Fabric Switches Application Centric Infrastructure Mode Root Privilege Escalation Vulnerability (cisco-sa-20190501-nexus9k-rpe) |
| code | |