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.
- Log source category
- crowdstrike_processrollup2sysmon_eventid_1windows_event_log_security_4688
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.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| www.mandiant.com/resources/fin7-spear-phishing-campaign-targets-personnel-involved-sec-filings | 2 |
| www.microsoft.com/security/blog/2021/01/20/deep-dive-into-the-solorigate-second-stage-activation-from-sunburst-to-teardrop-and-raindrop/ | 7from 2 sources |
| www.varonis.com/blog/dns-tunneling | 2 |
From the source
- At source
- Open at source
- Upstream identifier
- 0a69fdaa-a2b8-11eb-b16d-acde48001122
- Tagged by the source as
- Command And ControlData ExfiltrationDynamic DNSSuspicious DNS TrafficEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Published
- Sep 4, 2026
- Version
- 2