uberAgent ESA monitors outgoing DNS queries and their responses. This includes all DNS queries that are processed by the operating system.

Functionality

The implementation and functionality of DNS query monitoring differ between operating systems.

Windows

uberAgent uses the local DNS machine’s DNS resolver as the data source. uberAgent sees all DNS requests that are handled by the OS, including requests via encrypted DNS (DoT or DoH). uberAgent doesn’t see requests that bypass the OS resolver, e.g., requests from tools such as nslookup.

uberAgent cannot differentiate between requests that go over the wire and requests that can be answered from the local DNS cache. Both types of requests are collected by uberAgent.

macOS

uberAgent monitors network traffic at the packet level. uberAgent sees any and all DNS requests, but it cannot process encrypted DNS (DoT or DoH). uberAgent only collects requests that go over the wire, it doesn’t process requests that can be answered from the local DNS cache.

Configuration

uberAgent ESA DNS query monitoring is enabled or disabled through the timer metric DnsMonitoring. For Windows clients, this feature requires Windows 8.1 or newer versions of Windows since the data source for this event is not available in previous Windows versions, such as Windows 7. Enabling the metric on unsupported Windows versions has no effect. For macOS, all versions are supported.

Metadata

Sourcetype

DNS query monitoring events are sent with the sourcetype uberAgentESA:Process:DnsQuery (documentation). This feature may significantly increase the data volume and can be limited using event data filtering. uberAgent’s configuration includes a comprehensive set of rules to exclude known and harmless DNS requests.

Threat Detection

DNS monitoring events are also available via uberAgent’s Threat Detection engine. This allows the creation of rules to report specific DNS events (e.g., malicious events or threat detection).

Visualization

DNS query monitoring events are visualized in the DNS Exfiltration and Tunneling dashboard, which is part of the uberAgent_ESA Splunk searchhead app.