CVE-2022-20824 in NX-OS
Summary
by MITRE • 08/25/2022
A vulnerability in the Cisco Discovery Protocol feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with root privileges or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper input validation of specific values that are within a Cisco Discovery Protocol message. 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 execute arbitrary code with root privileges or cause the Cisco Discovery Protocol process to crash and restart multiple times, which would cause the affected device to reload, resulting in a DoS condition. Note: 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).
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Analysis
by VulDB Data Team • 10/01/2022
This vulnerability resides within the Cisco Discovery Protocol implementation in Cisco FXOS and NX-OS software versions, representing a critical security flaw that enables unauthorized code execution and denial of service conditions. The vulnerability stems from inadequate input validation mechanisms within the CDP message processing subsystem, specifically when handling certain parameter values in discovery protocol packets. The flaw exists at the network layer two interface where CDP operates as a proprietary protocol designed to facilitate device discovery and information exchange within local networks. Attackers exploiting this weakness can leverage the adjacent network access requirement to craft malicious CDP packets that bypass normal validation procedures, ultimately compromising system integrity and operational availability.
The technical exploitation of CVE-2022-20824 occurs through the manipulation of specific field values within CDP messages that are processed without proper sanitization or bounds checking. When an affected device receives a malformed CDP packet containing crafted data sequences, the software fails to validate input parameters before processing them, leading to potential buffer overflows or memory corruption conditions. This improper input validation aligns with CWE-20, which describes "Improper Input Validation" as a fundamental weakness allowing attackers to manipulate system behavior through malformed inputs. The vulnerability demonstrates how Layer 2 protocols can serve as attack vectors when proper validation controls are absent, as CDP operates at the data link layer and can be easily accessed by devices within the same broadcast domain.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and service disruption. An attacker achieving successful exploitation can execute arbitrary code with root privileges, effectively gaining full administrative control over the affected device. Additionally, the vulnerability can trigger repeated process crashes and system reloads, creating persistent denial of service conditions that can disrupt network operations and potentially cause cascading failures across dependent systems. This dual nature of exploitation makes the vulnerability particularly dangerous as it provides both persistent access and disruptive capabilities. The requirement for adjacent network access limits the attack surface but does not eliminate the threat, as local network compromise often provides access to critical infrastructure components.
Mitigation strategies for CVE-2022-20824 should prioritize immediate software patching through official Cisco security advisories, which typically address the root cause through enhanced input validation and proper parameter handling. Network segmentation and access controls can reduce exposure by limiting adjacent network access to only authorized devices, while monitoring systems should be deployed to detect anomalous CDP traffic patterns that may indicate exploitation attempts. The implementation of network access control lists and firewall rules can help restrict CDP traffic to trusted sources, and regular network audits should verify proper configuration of CDP settings across all affected devices. Organizations should also consider disabling CDP where it is not required for network operations, as this reduces the attack surface and eliminates the vulnerability vector entirely. These measures align with the principle of defense in depth and support the NIST cybersecurity framework's focus on protecting against known vulnerabilities through proper patch management and network segmentation practices.