command_and_control_headless_browser.toml

[metadata]
creation_date = "2024/05/10"
integration = ["endpoint", "windows", "system", "m365_defender", "sentinel_one_cloud_funnel", "crowdstrike"]
maturity = "production"
updated_date = "2025/02/24"
min_stack_version = "8.14.0"
min_stack_comments = "Breaking change at 8.14.0 for the Windows Integration."

[rule]
author = ["Elastic"]
description = """
Identifies the use of a browser to download a file from a remote URL and from a suspicious parent process. Adversaries
may use browsers to avoid ingress tool transfer restrictions.
"""
from = "now-9m"
index = [
    "endgame-*",
    "logs-crowdstrike.fdr*",
    "logs-endpoint.events.process-*",
    "logs-m365_defender.event-*",
    "logs-sentinel_one_cloud_funnel.*",
    "logs-system.security*",
    "logs-windows.forwarded*",
    "logs-windows.sysmon_operational-*",
    "winlogbeat-*",
]
language = "eql"
license = "Elastic License v2"
name = "Potential File Download via a Headless Browser"
note = """## Triage and analysis

### Investigating Potential File Download via a Headless Browser

- Investigate the process execution chain (parent process tree).
- Investigate the process network and file events.
- Identify the user account that performed the action and whether it should perform this kind of action.
- Contact the account owner and confirm whether they are aware of this activity.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Isolate the involved host to prevent further post-compromise behavior.
- If the triage identified malware, search the environment for additional compromised hosts.
  - Implement temporary network rules, procedures, and segmentation to contain the malware.
  - Stop suspicious processes.
  - Immediately block the identified indicators of compromise (IoCs).
  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
- Remove and block malicious artifacts identified during triage.
- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
"""
references = ["https://lolbas-project.github.io/lolbas/Binaries/Msedge/"]
risk_score = 73
rule_id = "5f2f463e-6997-478c-8405-fb41cc283281"
severity = "high"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Command and Control",
    "Resources: Investigation Guide",
    "Data Source: Windows",
    "Data Source: Elastic Endgame",
    "Data Source: Elastic Defend",
    "Data Source: Windows Security Event Logs",
    "Data Source: Microsoft Defender for Endpoint",
    "Data Source: SentinelOne",
    "Data Source: Sysmon",
    "Data Source: Crowdstrike",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where host.os.type == "windows" and event.type == "start" and
 process.name : ("chrome.exe", "msedge.exe", "brave.exe", "browser.exe", "dragon.exe", "vivaldi.exe") and
  (process.args : "--headless*" or process.args : "data:text/html;base64,*") and
  process.parent.name :
     ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe", "mshta.exe", "conhost.exe", "msiexec.exe",
      "explorer.exe", "rundll32.exe", "winword.exe", "excel.exe", "onenote.exe", "hh.exe", "powerpnt.exe", "forfiles.exe",
      "pcalua.exe", "wmiprvse.exe")
'''
setup = """## Setup

This rule requires data from one of the following integrations:
- Elastic Defend
- M365 Defender
- SentinelOne Cloud Funnel
- CrowdStrike

Note: This detection rule supports multiple datasets, but only one is required. Listed indexes and integrations should be interpreted as an OR condition, meaning any of them are supported.

### Elastic Defend Setup

Elastic Defend seamlessly integrates with Elastic Agent through Fleet. Once set up, it enables endpoint prevention and remediation capabilities and sends data that powers detection rules. For setup instructions, refer to our [documentation](https://www.elastic.co/guide/en/security/current/install-endpoint.html).

### SentinelOne Cloud Funnel Setup

This rule is compatible with telemetry generated by the SentinelOne XDR platform. For setup instructions, refer to the SentinelOne Cloud Funnel integration [documentation](https://www.elastic.co/guide/en/integrations/current/sentinel_one_cloud_funnel.html).

### Crowdstrike FDR Setup

This rule is compatible with telemetry generated by Crowdstrike FDR. For setup instructions, refer to the Crowdstrike FDR integration [documentation](https://www.elastic.co/guide/en/integrations/current/crowdstrike.html).

### Microsoft Defender for Endpoint Setup

This rule is compatible with telemetry generated by Microsoft Defender for Endpoint and collected via the Streaming API using the Microsoft M365 Defender integration. For setup instructions, refer to the Microsoft M365 Defender integration [documentation](https://www.elastic.co/guide/en/integrations/current/m365_defender.html).
"""


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1105"
name = "Ingress Tool Transfer"
reference = "https://attack.mitre.org/techniques/T1105/"


[rule.threat.tactic]
id = "TA0011"
name = "Command and Control"
reference = "https://attack.mitre.org/tactics/TA0011/"