The Patching Friars' AlmanacA calendar of CVE saints

February 5

CDPwnHoly card for cdpwn, generated with AI (Claude, Anthropic) for the Lunario dei Frati Patchatori.CC BY-NC-SA 4.0 CDP CDPwn VICINUS INSIDIATUR
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Saint CDPwn, Who Introduced Himself to the Neighbours

Patron of IP phones, surveillance cameras, and protocols that gossip on the local network.

Life

On 5 February 2020 Armis revealed five vulnerabilities in the Cisco Discovery Protocol, the protocol Cisco devices use to introduce themselves to their neighbours. A single well-crafted packet sent from the same local network was enough to take over Nexus switches, IOS XR routers, IP phones and cameras, or to make them reboot. Hopping from one device to the next, an attacker could cross the segmentation of a whole corporate network.

Prayer

O Saint CDPwn, who greets everyone with a packet in hand, let our devices not get too friendly with the first comer. Amen.

How to celebrate

Celebrated by updating IOS XR, NX-OS and phone firmware, and turning CDP off wherever nobody uses it.

Introduce yourself to everyone, and sooner or later you meet the wrong one.

Technical record

Disclosed on
February 5 2020
CVE
CVE-2020-3119CVE-2020-3118CVE-2020-3111CVE-2020-3110CVE-2020-3120
CVSS
8.8Actively exploited (CISA KEV)
Product
Cisco · Cisco Unified Computing System (Managed)

A vulnerability in the Cisco Discovery Protocol implementation for Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a reload on an affected device. The vulnerability exists because the Cisco Discovery Protocol parser does not properly validate input for certain fields in a Cisco Discovery Protocol message. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. An successful exploit could allow the attacker to cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges on an affected device. 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).

Sources: armis.com

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