sigma-rules/rules/ml/ml_windows_anomalous_process_all_hosts.toml

[metadata]
creation_date = "2020/03/25"
maturity = "production"
updated_date = "2021/05/10"

[rule]
anomaly_threshold = 50
author = ["Elastic"]
description = """
Searches for rare processes running on multiple hosts in an entire fleet or network. This reduces the detection of false
positives since automated maintenance processes usually only run occasionally on a single machine but are common to all
or many hosts in a fleet.
"""
false_positives = [
    """
    A newly installed program or one that runs rarely as part of a monthly or quarterly workflow could trigger this
    alert.
    """,
]
from = "now-45m"
interval = "15m"
license = "Elastic License v2"
machine_learning_job_id = ["windows_anomalous_process_all_hosts_ecs", "v2_windows_anomalous_process_all_hosts_ecs"]
name = "Anomalous Process For a Windows Population"
note = """## Triage and analysis

### Investigating an Unusual Windows Process
Detection alerts from this rule indicate the presence of a Windows process that is rare and unusual for all of the Windows hosts for which Winlogbeat data is available. Here are some possible avenues of investigation:
- Consider the user as identified by the username field. Is this program part of an expected workflow for the user who ran this program on this host?
- Examine the history of execution. If this process only manifested recently, it might be part of a new software package. If it has a consistent cadence (for example if it runs monthly or quarterly), it might be part of a monthly or quarterly business process.
- Examine the process metadata like the values of the Company, Description and Product fields which may indicate whether the program is associated with an expected software vendor or package.
- Examine arguments and working directory. These may provide indications as to the source of the program or the nature of the tasks it is performing.
- Consider the same for the parent process. If the parent process is a legitimate system utility or service, this could be related to software updates or system management. If the parent process is something user-facing like an Office application, this process could be more suspicious.
- If you have file hash values in the event data, and you suspect malware, you can optionally run a search for the file hash to see if the file is identified as malware by anti-malware tools. """
references = ["https://www.elastic.co/guide/en/security/current/prebuilt-ml-jobs.html"]
risk_score = 21
rule_id = "6e40d56f-5c0e-4ac6-aece-bee96645b172"
severity = "low"
tags = ["Elastic", "Host", "Windows", "Threat Detection", "ML"]
type = "machine_learning"