| ID | Technique | Tactic |
|---|---|---|
| T1048 | Exfiltration Over Alternative Protocol | Exfiltration |
Detection: DNS Exfiltration Using Nslookup App
Description
The following analytic identifies potential DNS exfiltration using the nslookup application. It detects specific command-line parameters such as query type (TXT, A, AAAA) and retry options, which are commonly used by attackers to exfiltrate data. The detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process execution logs. This activity is significant as it may indicate an attempt to communicate with a Command and Control (C2) server or exfiltrate sensitive data. If confirmed malicious, this could lead to data breaches and unauthorized access to critical information.
Search
1
2| tstats `security_content_summariesonly` values(Processes.process) as process values(Processes.process_id) as process_id values(Processes.parent_process) as parent_process count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
3 WHERE Processes.process_name = "nslookup.exe" Processes.process = "*-querytype=*"
4 OR
5 Processes.process="*-qt=*"
6 OR
7 Processes.process="*-q=*"
8 OR
9 Processes.process="*-type=*"
10 OR
11 Processes.process="*-retry=*"
12 BY Processes.action Processes.dest Processes.original_file_name
13 Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
14 Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
15 Processes.process Processes.process_exec Processes.process_guid
16 Processes.process_hash Processes.process_id Processes.process_integrity_level
17 Processes.process_name Processes.process_path Processes.user
18 Processes.user_id Processes.vendor_product
19
20| `drop_dm_object_name(Processes)`
21
22| `security_content_ctime(firstTime)`
23
24| `security_content_ctime(lastTime)`
25
26| `dns_exfiltration_using_nslookup_app_filter`
Data Source
| Name | Platform | Sourcetype | Source |
|---|---|---|---|
| CrowdStrike ProcessRollup2 | Other | 'crowdstrike:events:sensor' |
'crowdstrike' |
| Sysmon EventID 1 |  Windows |
'XmlWinEventLog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
| Windows Event Log Security 4688 | Windows |
'XmlWinEventLog' |
'XmlWinEventLog:Security' |
Macros Used
| Name | Value |
|---|---|
| security_content_summariesonly | summariesonly=summariesonly_config allow_old_summaries=oldsummaries_config fillnull_value=fillnull_config`` |
| dns_exfiltration_using_nslookup_app_filter | search * |
dns_exfiltration_using_nslookup_app_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
Actions on Objectives
DE.CM
CIS 10
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
| Setting | Value |
|---|---|
| Disabled | true |
| Cron Schedule | 0 * * * * |
| Earliest Time | -70m@m |
| Latest Time | -10m@m |
| Schedule Window | auto |
| Creates Finding (Notable) | Yes |
| Rule Title | %name% |
| Rule Description | %description% |
| Notable Event Fields | user, dest |
| Creates Intermediate Finding (Risk Event) | Yes |
TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.
Implementation
The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
Known False Positives
admin nslookup usage
Associated Analytic Story
Finding
| Title | Entity Field | Entity Type | Risk Score |
|---|---|---|---|
| An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ performing activity related to DNS exfiltration. | user | user | 50 |
Intermediate Findings
| Message | Entity Field | Entity Type | Risk Score |
|---|---|---|---|
| An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ performing activity related to DNS exfiltration. | dest | system | 50 |
Threat Objects
| Field | Type |
|---|---|
| process_name | process_name |
| parent_process_name | parent_process_name |
References
Detection Testing
| Test Type | Status | Dataset | Source | Sourcetype |
|---|---|---|---|---|
| Validation | ✅ Passing | N/A | N/A | N/A |
| Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
| Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 14