Back to results

Excessive Usage of NSLOOKUP App

The following analytic detects excessive usage of the nslookup application, which may indicate potential DNS exfiltration attempts. It leverages Sysmon EventCode 1 to monitor process executions, specifically focusing…

Description

The following analytic detects excessive usage of the nslookup application, which may indicate potential DNS exfiltration attempts. It leverages Sysmon EventCode 1 to monitor process executions, specifically focusing on nslookup.exe. The detection identifies outliers by comparing the frequency of nslookup executions against a calculated threshold. This activity is significant as it can reveal attempts by malware or APT groups to exfiltrate data via DNS queries. If confirmed malicious,this behavior could allow attackers to stealthily transfer sensitive information out of the network, bypassing traditional data exfiltration defenses.

Detection logic

Detection requirements

Platform
ESXiIaaSLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Known benign triggers

  • Network or DNS monitoring tools that perform bulk nslookup checks against multiple domains in quick succession (e.g., CDN health checks, load balancer DNS validation scripts) may exceed the detection threshold as part of normal, scheduled operation. Hosts with limited historical baseline data may also cross the dynamic threshold more easily due to low computed average and standard deviation values. Tune the detection or add exceptions for known monitoring tool parent processes as needed.

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice