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Tailscale: DNS nameservers modified

Description

Identifies when the tailnet's global DNS nameserver list is modified. Adding an attacker-controlled resolver as a tailnet-wide nameserver enables broad DNS hijacking for every device using MagicDNS resolution.

Rule type: Scheduled
Version: 1.0.0
Declared status: Available
Query frequency: 15m
Query period: 15m
Trigger: gt 0

Declared MITRE coverage

Declared sources

Metadata from the source file. No dependencies inferred from KQL.

Connectors

TailscaleCCF

Data types

Tailscale_Audit_CL

KQL query

Original query, unchanged.

Tailscale_Audit_CL
| where Action == "UPDATE"
| where tostring(Target.type) == "TAILNET"
| where tostring(Target.property) == "DNS_NAMESERVERS"
| extend ActorLogin = tostring(Actor.loginName)
| extend OldServers = Old.dns
| extend NewServers = New.dns
| extend Added = set_difference(NewServers, OldServers)
| extend Removed = set_difference(OldServers, NewServers)
| project TimeGenerated, ActorLogin, OldServers, NewServers, Added, Removed, Origin

Declared entities

Account

Source provenance

GitHub

Displayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.

File: Solutions/Tailscale (CCF)/Analytic Rules/TailscaleDnsNameserversModified.yaml ↗
Commit: 9800e51 ↗
Source identifier: c5d6e7f8-2345-6789-01ab-cdef12345011

Additional source files 2

Solutions/Tailscale (CCF)/Analytic Rules/TailscaleDnsNameserversModified.yamlsource ↗Solutions/Tailscale (CCF)/Data/Solution_Tailscale.jsonsolution-membership ↗

GSTEP / CATALOG TRACKING

Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC

GSTEP sync dates, separate from the source content’s publication dates.