Kubernetes Pod Exec Potential Reverse Shell

[metadata]
creation_date = "2026/04/23"
integration = ["kubernetes"]
maturity = "production"
updated_date = "2026/08/18"

[rule]
author = ["Elastic"]
description = """
Flags exec into a pod when the URL-decoded command payload resembles reverse-shell or bind-shell
one-liners invocation patterns. Legitimate debug sessions sometimes use similar building blocks, but together 
these patterns align with post-exploitation interactive access and command-and-control.
"""
from = "now-6m"
interval = "5m"
language = "esql"
license = "Elastic License v2"
name = "Kubernetes Pod Exec Potential Reverse Shell"
note = """## Triage and analysis

### Investigating Kubernetes Pod Exec Potential Reverse Shell

The rule inspects Kubernetes audit exec requestURI values, URL-decodes them, parses the command query fragment, and 
matches high-signal shell and socket idioms often used to obtain a fallback shell from inside a container.

### Possible investigation steps

- Identify the actor (kubernetes.audit.user.username, groups, impersonation), source IP, and user agent
  (human kubectl vs automation).
- Resolve the target namespace, pod, and container from kubernetes.audit.objectRef.* and correlate with
  workload ownership and change tickets.
- Pull the raw and decoded URI from the alert document and replay the inferred command in a sandbox only if policy
  allows—otherwise rely on audit and platform logs.
- Hunt nearby events from the same identity: secret reads, pods/exec to other workloads, RoleBinding
  changes, or anonymous API use.

### False positive analysis

- Security training, CTF-style images, or vendor diagnostics may include bash redirection or /dev/tcp examples;
  baseline approved images and break-glass accounts.
- Some observability or mesh sidecars use socat or sockets in ways that could overlap; validate container image and
  command lineage.

### Response and remediation

- If malicious, terminate the exec session, isolate the workload or node, rotate credentials reachable from the
  pod, and revoke pods/exec for the abused principal unless strictly required.
"""
references = [
    "https://attack.mitre.org/techniques/T1609/",
    "https://attack.mitre.org/techniques/T1059/",
]
risk_score = 73
rule_id = "f1a2b3c4-d5e6-4789-a012-3456789abc01"
severity = "high"
tags = [
    "Data Source: Kubernetes",
    "Data Source: Kubernetes API Server Audit Logs",
    "Domain: Kubernetes",
    "Platform: Kubernetes",
    "Use Case: Threat Detection",
    "Tactic: Execution",
    "Tactic: Command and Control",
    "Resources: Investigation Guide",
]
timestamp_override = "event.ingested"
type = "esql"
query = '''
FROM logs-kubernetes.audit_logs-* metadata _id, _index, _version
| WHERE kubernetes.audit.objectRef.subresource == "exec"
  AND kubernetes.audit.requestURI LIKE "*command=*"
| EVAL Esql.decoded_uri = URL_DECODE(kubernetes.audit.requestURI)
| GROK Esql.decoded_uri "%{DATA}/exec\\?%{DATA:raw_commands}&(?:container|stdin|stdout|stderr)=%{GREEDYDATA}"
| EVAL command = REPLACE(raw_commands, "command=", "")
| EVAL command = REPLACE(command, "&", " ")
| EVAL Esql.executed_command = REPLACE(command, "\\+", " ")
| WHERE Esql.executed_command IS NOT NULL AND command RLIKE """.*(/dev/tcp/|/dev/udp/|zsh/net/tcp|zsh/net/udp|nc\s+-e|ncat\s+-e|netcat\s+-e|nc\s.*\s-c\s|mkfifo|socat\s.*exec|socat\s.*pty|bash\s+-i\s+>&|0>&1|>&\s*/dev/tcp|import\s+socket.*connect|import\s+pty.*spawn|socket\.socket.*connect|IO::Socket::INET|fsockopen|TCPSocket\.new|/inet/tcp/).*""" AND 
  // local service health check patterns
  NOT command RLIKE """.*/dev/tcp/(localhost|127\.0\.0\.1)/(8080|8443|9090|3000|5000|8888|80|443).*"""
| KEEP Esql.*, user.name, user_agent.original, event.*, source.ip, kubernetes.audit.*, _id, _version, _index, data_stream.namespace
'''

[[rule.threat]]
framework = "MITRE ATT&CK"

[[rule.threat.technique]]
id = "T1609"
name = "Container Administration Command"
reference = "https://attack.mitre.org/techniques/T1609/"

[[rule.threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"

[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"