Kubernetes Scanner Image Pulling

Status: production
Severity: medium
Group by: host, kind, message, name, namespace, phase, reason, severity
Author: Patrick Bareiss, Splunk
Source: github.com/splunk/security_content

The following analytic detects the pulling of known Kubernetes security scanner images such as kube-hunter, kube-bench, and kube-recon. It leverages Kubernetes logs ingested through Splunk Connect for Kubernetes, specifically monitoring for messages indicating the pulling of these images. This activity is significant because the use of security scanners can indicate an attempt to identify vulnerabilities within the Kubernetes environment. If confirmed malicious, this could lead to the discovery and exploitation of security weaknesses, potentially compromising the entire Kubernetes cluster.

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1526` Cloud Service Discovery

Rule body splunk

name: Kubernetes Scanner Image Pulling
id: 4890cd6b-0112-4974-a272-c5c153aee551
version: 10
creation_date: '2021-08-24'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic detects the pulling of known Kubernetes security scanner images such as kube-hunter, kube-bench, and kube-recon. It leverages Kubernetes logs ingested through Splunk Connect for Kubernetes, specifically monitoring for messages indicating the pulling of these images. This activity is significant because the use of security scanners can indicate an attempt to identify vulnerabilities within the Kubernetes environment. If confirmed malicious, this could lead to the discovery and exploitation of security weaknesses, potentially compromising the entire Kubernetes cluster.
data_source: []
search: |-
    `kube_objects_events` object.message IN ("Pulling image *kube-hunter*", "Pulling image *kube-bench*", "Pulling image *kube-recon*", "Pulling image *kube-recon*")
      | rename object.* AS *
      | rename involvedObject.* AS *
      | rename source.host AS host
      | eval phase="operate"
      | eval severity="high"
      | stats min(_time) as firstTime max(_time) as lastTime count
        BY host, name, namespace,
           kind, reason, message,
           phase, severity
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `kubernetes_scanner_image_pulling_filter`
how_to_implement: You must ingest Kubernetes logs through Splunk Connect for Kubernetes.
known_false_positives: No false positives have been identified at this time.
references:
    - https://github.com/splunk/splunk-connect-for-kubernetes
drilldown_searches:
    - name: View the detection results for - "$host$"
      search: '%original_detection_search% | search  host = "$host$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$host$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$host$") | 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"
finding:
    title: Kubernetes Scanner image pulled on host $host$
    entity:
        field: host
        type: system
        score: 50
analytic_story:
    - Dev Sec Ops
asset_type: Kubernetes
mitre_attack_id:
    - T1526
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: network
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1526/kubernetes_kube_hunter/kubernetes_kube_hunter.json
          sourcetype: kube:objects:events
          source: kubernetes
      test_type: unit

Stages and Predicates

Stage 1: `search`

`kube_objects_events` object.message IN ("Pulling image *kube-hunter*", "Pulling image *kube-bench*", "Pulling image *kube-recon*", "Pulling image *kube-recon*")

Stage 2: `rename`

| rename object.* AS *

Stage 3: `rename`

| rename involvedObject.* AS *

Stage 4: `rename`

| rename source.host AS host

Stage 5: `eval`

| eval phase="operate"

Stage 6: `eval`

| eval severity="high"

Stage 7: `stats`

| stats min(_time) as firstTime max(_time) as lastTime count
    BY host, name, namespace,
       kind, reason, message,
       phase, severity

Stage 8: `search`

| `security_content_ctime(firstTime)`

Stage 9: `search`

| `security_content_ctime(lastTime)`

Stage 10: `search`

| `kubernetes_scanner_image_pulling_filter`

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
`object.message`	in	`"Pulling image kube-bench"` `"Pulling image kube-hunter"` `"Pulling image kube-recon"`
`sourcetype`	eq	`kube:objects:events`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Kubernetes Scanner Image Pulling

MITRE ATT&CK coverage

Rule body splunk

Stages and Predicates

Stage 1: `search`

Stage 2: `rename`

Stage 3: `rename`

Stage 4: `rename`

Stage 5: `eval`

Stage 6: `eval`

Stage 7: `stats`

Stage 8: `search`

Stage 9: `search`

Stage 10: `search`

Indicators

Keyboard shortcuts

Search operators

Kubernetes Scanner Image Pulling

MITRE ATT&CK coverage

Rule body splunk

Stages and Predicates

Stage 1: search

Stage 2: rename

Stage 3: rename

Stage 4: rename

Stage 5: eval

Stage 6: eval

Stage 7: stats

Stage 8: search

Stage 9: search

Stage 10: search

Indicators

Stage 1: `search`

Stage 2: `rename`

Stage 3: `rename`

Stage 4: `rename`

Stage 5: `eval`

Stage 6: `eval`

Stage 7: `stats`

Stage 8: `search`

Stage 9: `search`

Stage 10: `search`