Detection rules › Splunk
ESXi Shared or Stolen Root Account
This detection monitors for signs of a shared or potentially compromised root account on ESXi hosts by tracking the number of unique IP addresses logging in as root within a short time window. Multiple logins from different IPs in a brief period may indicate credential misuse, lateral movement, or account compromise.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1078 Valid Accounts |
| Persistence | T1078 Valid Accounts |
| Privilege Escalation | T1078 Valid Accounts |
| Stealth | T1078 Valid Accounts |
Rule body splunk
name: ESXi Shared or Stolen Root Account
id: 1bc8f235-5d7c-457c-95ca-5e92edcb52ea
version: 4
creation_date: '2025-07-11'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: This detection monitors for signs of a shared or potentially compromised root account on ESXi hosts by tracking the number of unique IP addresses logging in as root within a short time window. Multiple logins from different IPs in a brief period may indicate credential misuse, lateral movement, or account compromise.
data_source:
- VMWare ESXi Syslog
search: '`esxi_syslog` Message="*root*" Message="*logged in*" NOT Message="*root@127.0.0.1*" | rex field=_raw "root@(?<SrcIpAddr>\d{1,3}(?:\.\d{1,3}){3})" | rex field=_raw "Z (?<dest>[\w\.]+)\s" | bin _time span=15m | stats min(_time) as firstTime max(_time) as lastTime dc(SrcIpAddr) AS distinct_ip_count values(SrcIpAddr) AS SrcIps by dest | where distinct_ip_count > 1 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_shared_or_stolen_root_account_filter`'
how_to_implement: This is based on syslog data generated by VMware ESXi hosts. To implement this search, you must configure your ESXi systems to forward logs to your Splunk deployment. These logs must be ingested with the appropriate Splunk Technology Add-on for VMware ESXi Logs, which provides field extractions and CIM compatibility.
known_false_positives: Limited false positives in most environments, however tune as needed
references:
- https://detect.fyi/detecting-and-responding-to-esxi-compromise-with-splunk-f33998ce7823
drilldown_searches:
- name: View the detection results for - "$dest$"
search: '%original_detection_search% | search dest = "$dest$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$dest$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | 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: dest
type: system
score: 20
message: Root login from multiple IPs on ESXi host $dest$.
analytic_story:
- ESXi Post Compromise
- Black Basta Ransomware
asset_type: Infrastructure
mitre_attack_id:
- T1078
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: application
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1078/esxi_stolen_root_account/esxi_stolen_root_account.log
source: vmware:esxlog
sourcetype: vmw-syslog
test_type: unit
Stages and Predicates
Stage 1: search
`esxi_syslog` Message="*root*" Message="*logged in*" NOT Message="*root@127.0.0.1*"
Stage 2: rex
| rex field=_raw "root@(?<SrcIpAddr>\d{1,3}(?:\.\d{1,3}){3})"
Stage 3: rex
| rex field=_raw "Z (?<dest>[\w\.]+)\s"
Stage 4: bucket
| bin _time span=15m
Stage 5: stats
| stats min(_time) as firstTime max(_time) as lastTime dc(SrcIpAddr) AS distinct_ip_count values(SrcIpAddr) AS SrcIps by dest
Stage 6: where
| where distinct_ip_count > 1
Stage 7: search
| `security_content_ctime(firstTime)`
Stage 8: search
| `security_content_ctime(lastTime)`
Stage 9: search
| `esxi_shared_or_stolen_root_account_filter`
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
Message | eq | "*root@127.0.0.1*" |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Message | eq |
|
distinct_ip_count | gt |
|
sourcetype | in |
|