CVE-2020-3120:Cisco FXOS, IOS XR, and NX-OS Software Cisco Discovery Protocol Denial of Service Vulnerability

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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.

Overview

CVE-2020-3120 is an integer overflow vulnerability (CWE-190) affecting Cisco's Discovery Protocol implementation in multiple Cisco operating systems. This vulnerability allows an attacker who is in the same broadcast domain (Layer 2 adjacent) to send specially crafted CDP packets that can exhaust system memory resources. When successful, the attack causes the affected device to reload, creating a denial of service condition that disrupts network operations. Since CDP is a Layer 2 protocol, the attacker must have direct network access to the vulnerable device, but does not need authentication credentials to exploit the vulnerability.

Remediation

To address this vulnerability, network administrators should:

  1. Update affected Cisco devices to the latest software versions as specified in the Cisco Security Advisory.
  2. If immediate patching is not possible, consider disabling CDP on interfaces where it is not operationally required, especially on interfaces facing untrusted networks.
  3. Implement network segmentation to limit the potential attack surface.
  4. Monitor systems for unexpected reloads that might indicate exploitation attempts.
  5. Ensure physical security of network equipment to prevent unauthorized adjacent access.

References

  1. Cisco Security Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200205-fxnxos-iosxr-cdp-dos
  2. Packet Storm Security Advisory: http://packetstormsecurity.com/files/156203/Cisco-Discovery-Protocol-CDP-Remote-Device-Takeover.html
  3. CWE-190: Integer Overflow or Wraparound - https://cwe.mitre.org/data/definitions/190.html

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Public Administration: Medium
    Public Administration
  2. Manufacturing: Medium
    Manufacturing
  3. Health Care & Social Assistance: Medium
    Health Care & Social Assistance
  4. Retail Trade: Low
    Retail Trade
  5. Finance and Insurance: Low
    Finance and Insurance
  6. Educational Services: Low
    Educational Services
  7. Transportation & Warehousing: Low
    Transportation & Warehousing
  8. Utilities: Low
    Utilities
  9. Other Services (except Public Administration): Low
    Other Services (except Public Administration)
  10. Arts, Entertainment & Recreation: Low
    Arts, Entertainment & Recreation
  11. Management of Companies & Enterprises: Low
    Management of Companies & Enterprises
  12. Accommodation & Food Services: Low
    Accommodation & Food Services
  13. Information: Low
    Information
  14. Professional, Scientific, & Technical Services: Low
    Professional, Scientific, & Technical Services
  15. Real Estate Rental & Leasing: Low
    Real Estate Rental & Leasing
  16. Administrative, Support, Waste Management & Remediation Services: Low
    Administrative, Support, Waste Management & Remediation Services
  17. Agriculture, Forestry Fishing & Hunting: Low
    Agriculture, Forestry Fishing & Hunting
  18. Construction: Low
    Construction
  19. Mining: Low
    Mining
  20. Wholesale Trade: Low
    Wholesale Trade

Focus on What Matters

  1. See Everything.
  2. Identify True Risk.
  3. Proactively Mitigate Threats.

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