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MDNS spoofing

Description​

The configuration of the MDNS services allows an attacker to spoof IP addresses effectively hijacking them or causing a denial-of-service. Alternatively, due to a lack of certain security measures, it is possible to intercept requests to mDNS services and obtain information about the connected devices.

Impact​

Attack vector because it is possible to extract administrative credentials from the process cache.

Recommendation​

Disable LLMR and NBT-NS. Configure the firewall to filter incoming connections from UDP 5353 port.

Threat​

Anonymous attacker from local network.

Expected Remediation Time​

⌚ 60 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the src.

Base​

  • Attack vector: N
  • Attack complexity: L
  • Privileges required: L
  • User interaction: N
  • Scope: C
  • Confidentiality: L
  • Integrity: L
  • Availability: N

Temporal​

  • Exploit code madurity: P
  • Remediation level: T
  • Report confidence: X

Result​

  • Vector string: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N/E:P/RL:T/RC:X
  • Score:
    • Base: 6.4
    • Temporal: 5.8
  • Severity:
    • Base: Medium
    • Temporal: Medium

Compliant code​

Verify that the application does not allow LLMNR and NBT-NS

gateway: "My gateway name"
firewall_service:
  enabled: true
  policy: 'drop'
  log_default_action: true
  firewall_rules:
  - :id: '1'
    :enabled: true
    :description: 'disallow_connections'
    :policy: 'disallow'
    :destination_port_range: '5353'
    :destination_ip: '00.01.02.03'
    :source_port_range: '5353'
    :source_ip: 'Any'

Non compliant code​

Network configuration that allows LLMNR

gateway: "My gateway name"
firewall_service:
  enabled: true
  policy: 'drop'
  log_default_action: true
  firewall_rules:
  - :id: '1'
    :enabled: true
    :llmnr: true
    :destination_port_range: '5353'
    :destination_ip: '00.01.02.03'
    :source_port_range: '5353'
    :source_ip: 'Any'

Requirements​

Fixes​

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