defense_evasion_whitespace_padding_in_command_line.toml

[metadata]
creation_date = "2021/07/30"
maturity = "production"
updated_date = "2021/07/30"

[rule]
author = ["Elastic"]
description = """
Identifies process execution events where the command line value contains a long sequence of whitespace characters or 
multiple occurrences of contiguous whitespace. Attackers may attempt to evade signature-based detections by padding 
their malicious command with unnecessary whitespace characters. These observations should be investigated for malicious 
behavior.
"""
from = "now-9m"
index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*"]
language = "eql"
license = "Elastic License v2"
name = "Whitespace Padding in Process Command Line"
note = """## Triage and analysis

- Analyze the command line of the process in question for evidence of malicious code execution.
- Review the ancestor and child processes spawned by the process in question for indicators of further malicious code execution."""
references = ["https://twitter.com/JohnLaTwC/status/1419251082736201737"]
risk_score = 47
rule_id = "e0dacebe-4311-4d50-9387-b17e89c2e7fd"
severity = "medium"
tags = ["Elastic", "Host", "Windows", "Threat Detection", "Defense Evasion"]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where event.type in ("start", "process_started") and
  process.command_line regex ".*[ ]{20,}.*" or 
  
  /* this will match on 3 or more separate occurrences of 5+ contiguous whitespace characters */
  process.command_line regex ".*(.*[ ]{5,}[^ ]*){3,}.*"
'''

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

[rule.threat.tactic]
id = "TA0005"
reference = "https://attack.mitre.org/tactics/TA0005/"
name = "Defense Evasion"