Cisco FXOS/IOS XR/NX-OS Discovery Protocol integer overflow

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Cisco FXOS, IOS XR and NX-OS. The impacted element is an unknown function of the component Discovery Protocol. The manipulation leads to integer overflow. This vulnerability is uniquely identified as CVE-2020-3120. The attack can only be initiated within the local network. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Cisco FXOS, IOS XR and NX-OS (Router Operating System) (affected version unknown). This issue affects an unknown functionality of the component Discovery Protocol. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is availability. The summary by CVE is:

A vulnerability in the Cisco Discovery Protocol implementation for Cisco FXOS Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing check when the affected software processes Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to exhaust system memory, causing the device to reload. Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

The weakness was disclosed 02/05/2020 as cisco-sa-20200205-fxnxos-iosxr as confirmed advisory (Website). The advisory is shared at tools.cisco.com. The identification of this vulnerability is CVE-2020-3120 since 12/12/2019. The attack can only be done within the local network. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/06/2020). The advisory points out:

The vulnerability is due to a missing check when the affected software processes Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to exhaust system memory, causing the device to reload.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• FXOS
• IOS XR
• NX-OS

License

• commercial

Website

• Vendor: https://www.cisco.com/

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