Google Cloud Kubernetes CronJob

Status: test
Severity: medium
Log source: product gcp, service gcp.audit
Author: Austin Songer @austinsonger
Source: github.com/SigmaHQ/sigma

Identifies when a Google Cloud Kubernetes CronJob runs in Azure Cloud. Kubernetes Job is a controller that creates one or more pods and ensures that a specified number of them successfully terminate. Kubernetes Job can be used to run containers that perform finite tasks for batch jobs. Kubernetes CronJob is used to schedule Jobs. An Adversary may use Kubernetes CronJob for scheduling execution of malicious code that would run as a container in the cluster.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique
Persistence	No specific technique
Privilege Escalation	No specific technique

Rule body yaml

title: Google Cloud Kubernetes CronJob
id: cd3a808c-c7b7-4c50-a2f3-f4cfcd436435
status: test
description: |
    Identifies when a Google Cloud Kubernetes CronJob runs in Azure Cloud. Kubernetes Job is a controller that creates one or more pods and ensures that a specified number of them successfully terminate.
    Kubernetes Job can be used to run containers that perform finite tasks for batch jobs. Kubernetes CronJob is used to schedule Jobs.
    An Adversary may use Kubernetes CronJob for scheduling execution of malicious code that would run as a container in the cluster.
references:
    - https://cloud.google.com/kubernetes-engine/docs
    - https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/
    - https://kubernetes.io/docs/concepts/workloads/controllers/job/
author: Austin Songer @austinsonger
date: 2021-11-22
modified: 2022-12-25
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.execution
logsource:
    product: gcp
    service: gcp.audit
detection:
    selection:
        gcp.audit.method_name:
            - io.k8s.api.batch.v*.Job
            - io.k8s.api.batch.v*.CronJob
    condition: selection
falsepositives:
    - Google Cloud Kubernetes CronJob/Job may be done by a system administrator.
    - If known behavior is causing false positives, it can be exempted from the rule.
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    gcp.audit.method_name:
        - io.k8s.api.batch.v*.Job
        - io.k8s.api.batch.v*.CronJob

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
`gcp.audit.method_name`	wildcard	`io.k8s.api.batch.v.CronJob` `io.k8s.api.batch.v.Job`

`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)

Google Cloud Kubernetes CronJob

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

Google Cloud Kubernetes CronJob

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`