Researchers find several flaws in a proprietary protocol used by many Cisco devices.
Background
On February 5, researchers at Armis Security announced their discovery of five vulnerabilities in the Cisco Discovery Protocol, a proprietary protocol designed to allow for discovery and communication between Cisco devices.
Analysis
CDPwn is a series of vulnerabilities in Cisco Discovery Protocol due to improper validation of Cisco Discovery Protocol messages. By sending a specially crafted packet to a vulnerable device, an unauthenticated, adjacent attacker could achieve remote code execution or create a denial of service condition.
Cisco notes in their advisories that because Cisco Discovery Protocol is a Layer 2 protocol, an attacker “must be in the same broadcast domain as the affected device.”
The following are the five vulnerabilities disclosed by Armis:
| CVE | Title | CVSSv3 |
|---|---|---|
| CVE-2020-3110 | Cisco Video Surveillance 8000 Series IP Cameras Cisco Discovery Protocol Remote Code Execution and Denial of Service Vulnerability | 8.8 |
| CVE-2020-3111 | Cisco IP Phone Remote Code Execution and Denial of Service Vulnerability | 8.8 |
| CVE-2020-3118 | Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability | 8.8 |
| CVE-2020-3119 | Cisco NX-OS Software Cisco Discovery Protocol Remote Code Execution Vulnerability | 8.8 |
| CVE-2020-3120 | Cisco FXOS, IOS XR, and NX-OS Software Cisco Discovery Protocol Denial of Service Vulnerability | 7.4 |
According to Armis, these vulnerabilities “affect tens of million devices” including Cisco NX-OS switches, Cisco IOS XR routers, Cisco NCS Systems, Cisco 8000 IP Cameras, Cisco Firepower Firewalls, and Cisco IP Phone 7800 and 8800 Series.
Exploitation requires the Cisco Discovery Protocol to be enabled and Cisco notes that it is enabled by default on certain devices using NX-OS and FXOS, though it is not enabled by default on routers using Cisco IOS XR.
Proof of concept
At the time this blog was published, there was no proof-of-concept code for any of the CDPwn vulnerabilities disclosed by Armis.
Solution
Cisco has released software updates to address these vulnerabilities. They’ve identified a list of vulnerable and not vulnerable products. The list below contains links to the respective section of each advisory that identifies vulnerable products.
Identifying affected systems
A list of Tenable plugins to identify these vulnerabilities will appear here as they’re released.
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