Cisco NVM - Suspicious Network Connection to IP Lookup Service API
SPLUNK detection rule by Nasreddine Bencherchali, Splunk, Janantha Marasinghe · Apache-2.0
This analytic identifies non-browser processes reaching out to public IP lookup or geolocation services,
such as `ipinfo.io`, `icanhazip.com`, `ip-api.com`, and others.
These domains are commonly used by legitimate tools, but their usage outside of browsers may indicate
network reconnaissance, virtual machine detection, or staging by malware.
This activity is observed in post-exploitation frameworks, stealer malware, and advanced threat actor campaigns.
The detection relies on Cisco Network Visibility Module (NVM) telemetry and excludes known browser
processes to reduce noise.
name: Cisco NVM - Suspicious Network Connection to IP Lookup Service API
id: 568cb83e-d79e-4a23-85ec-6e1f6c30cb2f
version: 8
creation_date: '2025-07-01'
modification_date: '2026-07-14'
author: Nasreddine Bencherchali, Splunk, Janantha Marasinghe
status: production
type: Anomaly
description: |
This analytic identifies non-browser processes reaching out to public IP lookup or geolocation services,
such as `ipinfo.io`, `icanhazip.com`, `ip-api.com`, and others.
These domains are commonly used by legitimate tools, but their usage outside of browsers may indicate
network reconnaissance, virtual machine detection, or staging by malware.
This activity is observed in post-exploitation frameworks, stealer malware, and advanced threat actor campaigns.
The detection relies on Cisco Network Visibility Module (NVM) telemetry and excludes known browser
processes to reduce noise.
data_source:
- Cisco Network Visibility Module Flow Data
search: |
`cisco_network_visibility_module_flowdata`
dest_hostname IN (
"*api.2ip.ua*", "*api.bigdatacloud.net*", "*api.ipify.org*", "*whatismyipaddress.com*",
"*canireachthe.net*", "*checkip.amazonaws.com*", "*checkip.dyndns.org*", "*curlmyip.com*",
"*db-ip.com*", "*edns.ip-api.com*", "*eth0.me*", "*freegeoip.app*", "*geoipy.com*", "*getip.pro*",
"*icanhazip.com*", "*ident.me*", "*ifconfig.io*", "*ifconfig.me*", "*ip-api.com*", "*ip.360.cn*",
"*ip.anysrc.net*", "*ip.taobao.com*", "*ip.tyk.nu*", "*ipaddressworld.com*", "*ipapi.co*",
"*ipconfig.io*", "*ipecho.net*", "*ipinfo.io*", "*ipip.net*", "*iplocation.net*",
"*ipof.in*", "*ipv6-test.com*", "*ipwho.is*", "*trackip.net*", "*inet-ip.info*",
"*jsonip.com*", "*myexternalip.com*", "*seeip.org*", "*wgetip.com*",
"*whatismyip.akamai.com*", "*whois.pconline.com.cn*", "*wtfismyip.com*", "*ip.cn"
)
NOT process_name IN (
"brave.exe", "chrome.exe", "firefox.exe", "iexplore.exe", "maxthon.exe",
"MicrosoftEdge.exe", "msedge.exe", "msedgewebview2.exe", "opera.exe", "safari.exe",
"seamonkey.exe", "vivaldi.exe", "whale.exe"
)
| stats count min(_time) as firstTime max(_time) as lastTime
values(parent_process_arguments) as parent_process_arguments
values(process_arguments) as process_arguments
values(parent_process_hash) as parent_process_hash
values(process_hash) as process_hash
values(module_name_list) as module_name_list
values(module_hash_list) as module_hash_list
values(dest_port) as dest_port
values(aliul) as additional_logged_in_users_list
values(dest_hostname) as dest_hostname
by src dest parent_process_path parent_process_integrity_level process_path process_name process_integrity_level process_id transport
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| table
parent_process_integrity_level parent_process_path parent_process_arguments parent_process_hash
process_integrity_level process_path process_name process_arguments process_hash process_id
additional_logged_in_users_list module_name_list module_hash_list
src dest_hostname dest dest_port transport firstTime lastTime
| `cisco_nvm___suspicious_network_connection_to_ip_lookup_service_api_filter`
how_to_implement: |
This search requires Network Visibility Module logs, which includes the flow data sourcetype.
This search uses an input macro named `cisco_network_visibility_module_flowdata`.
We strongly recommend that you specify your environment-specific configurations
(index, source, sourcetype, etc.) for Cisco Network Visibility Module logs.
Replace the macro definition with configurations for your Splunk environment.
The search also uses a post-filter macro designed to filter out known false positives.
The logs are to be ingested using the Splunk Add-on for Cisco Endpoint Security Analytics (CESA) (https://splunkbase.splunk.com/app/4221).
known_false_positives: |
Internal scripts or agents performing network checks may query IP geolocation services.
Tune by excluding known tools or adding internal allowlists for destination domains or process names and commandlines.
references:
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/network_connection/net_connection_win_domain_external_ip_lookup.yml
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa20-302a
drilldown_searches:
- name: View the detection results for - "$src$"
search: '%original_detection_search% | search src = "$src$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$src$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
intermediate_findings:
entities:
- field: src
type: system
score: 20
message: The host $src$ made a network request to IP lookup service $dest_hostname$ using suspicious process $process_path$
threat_objects:
- field: process_name
type: process_name
analytic_story:
- Cisco Network Visibility Module Analytics
- Castle RAT
- BlankGrabber Stealer
asset_type: Endpoint
mitre_attack_id:
- T1590.005
- T1016
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
- name: True Positive Test - Cisco NVM
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/cisco_network_visibility_module/cisco_nvm_flowdata/nvm_flowdata.log
source: not_applicable
sourcetype: cisco:nvm:flowdata:v2
test_type: unit
CIRCL