Cisco NX-OS CLI command injection

Summaryinfo

A vulnerability classified as critical has been found in Cisco NX-OS. Affected by this issue is some unknown functionality of the component CLI. Performing a manipulation results in command injection. This vulnerability is reported as CVE-2017-12339. The attack requires a local approach. No exploit exists.

Detailsinfo

A vulnerability was found in Cisco NX-OS (Router Operating System) (version now known). It has been classified as critical. This affects some unknown processing of the component CLI. The manipulation with an unknown input leads to a command injection vulnerability. CWE is classifying the issue as CWE-77. The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A vulnerability in the CLI of Cisco NX-OS System Software could allow an authenticated, local attacker to perform a command injection attack. The vulnerability is due to insufficient input validation of command arguments to the CLI parser. An attacker could exploit this vulnerability by injecting crafted command arguments into a vulnerable CLI command. An exploit could allow the attacker to execute arbitrary commands at the user's privilege level. On products that support multiple virtual device contexts (VDCs), this vulnerability could allow the attacker to execute commands at the user's privilege level outside the user's environment. This vulnerability affects the following products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 5000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode, Nexus 9000 Series Switches in standalone NX-OS mode, and Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCve99925, CSCvf15164, CSCvf15167, CSCvf15170, CSCvf15173.

The bug was discovered 11/29/2017. The weakness was disclosed 11/30/2017 as cisco-sa-20171129-nxos7 as confirmed advisory (Website). It is possible to read the advisory at tools.cisco.com. This vulnerability is uniquely identified as CVE-2017-12339 since 08/03/2017. Attacking locally is a requirement. Required for exploitation is a authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 01/25/2021). The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

The vulnerability was handled as a non-public zero-day exploit for at least 1 days. During that time the estimated underground price was around $5k-$25k. The commercial vulnerability scanner Qualys is able to test this issue with plugin 316172 (Cisco NX-OS System Software CLI Command Injection Vulnerability (cisco-sa-20171129-nxos7)).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at SecurityFocus (BID 102198†). The entries VDB-110070, VDB-110069, VDB-110068 and VDB-110065 are pretty similar. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• NX-OS

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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