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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 vulnerability.

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

Code Examples

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_conections'
: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