[metadata]
creation_date = "2021/03/04"
integration = ["endpoint", "windows", "system", "m365_defender", "sentinel_one_cloud_funnel", "crowdstrike"]
maturity = "production"
updated_date = "2024/10/31"
min_stack_version = "8.14.0"
min_stack_comments = "Breaking change at 8.14.0 for the Windows Integration."

[rule]
author = ["Elastic", "Austin Songer"]
description = """
Identifies suspicious processes being spawned by the Microsoft Exchange Server Unified Messaging (UM) service. This
activity has been observed exploiting CVE-2021-26857.
"""
false_positives = [
    """
    Legitimate processes may be spawned from the Microsoft Exchange Server Unified Messaging (UM) service. If known
    processes are causing false positives, they can be exempted from the rule.
    """,
]
from = "now-9m"
index = [
    "logs-endpoint.events.process-*",
    "winlogbeat-*",
    "logs-windows.forwarded*",
    "logs-windows.sysmon_operational-*",
    "endgame-*",
    "logs-system.security*",
    "logs-m365_defender.event-*",
    "logs-sentinel_one_cloud_funnel.*",
    "logs-crowdstrike.fdr*",
]
language = "eql"
license = "Elastic License v2"
name = "Microsoft Exchange Server UM Spawning Suspicious Processes"
references = [
    "https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers",
    "https://www.volexity.com/blog/2021/03/02/active-exploitation-of-microsoft-exchange-zero-day-vulnerabilities",
]
risk_score = 47
rule_id = "483c4daf-b0c6-49e0-adf3-0bfa93231d6b"
severity = "medium"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Initial Access",
    "Tactic: Lateral Movement",
    "Data Source: Elastic Endgame",
    "Use Case: Vulnerability",
    "Data Source: Elastic Defend",
    "Data Source: System",
    "Data Source: Microsoft Defender for Endpoint",
    "Data Source: Sysmon",
    "Data Source: SentinelOne",
    "Data Source: Crowdstrike",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where host.os.type == "windows" and event.type == "start" and
  process.parent.name : ("UMService.exe", "UMWorkerProcess.exe") and
    not process.executable : (
          "?:\\Windows\\System32\\werfault.exe",
          "?:\\Windows\\System32\\wermgr.exe",
          "?:\\Program Files\\Microsoft\\Exchange Server\\V??\\Bin\\UMWorkerProcess.exe",
          "?:\\Program Files\\Microsoft\\Exchange Server\\Bin\\UMWorkerProcess.exe",
          "D:\\Exchange 2016\\Bin\\UMWorkerProcess.exe",
          "E:\\ExchangeServer\\Bin\\UMWorkerProcess.exe",
          "D:\\Exchange\\Bin\\UMWorkerProcess.exe",
          "D:\\Exchange Server\\Bin\\UMWorkerProcess.exe",
          "E:\\Exchange Server\\V15\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Windows\\System32\\werfault.exe",
          "\\Device\\HarddiskVolume?\\Windows\\System32\\wermgr.exe",
          "\\Device\\HarddiskVolume?\\Program Files\\Microsoft\\Exchange Server\\V??\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Program Files\\Microsoft\\Exchange Server\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Exchange 2016\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\ExchangeServer\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Exchange\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Exchange Server\\Bin\\UMWorkerProcess.exe",
          "\\Device\\HarddiskVolume?\\Exchange Server\\V15\\Bin\\UMWorkerProcess.exe"
    )
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1190"
name = "Exploit Public-Facing Application"
reference = "https://attack.mitre.org/techniques/T1190/"


[rule.threat.tactic]
id = "TA0001"
name = "Initial Access"
reference = "https://attack.mitre.org/tactics/TA0001/"
[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1210"
name = "Exploitation of Remote Services"
reference = "https://attack.mitre.org/techniques/T1210/"


[rule.threat.tactic]
id = "TA0008"
name = "Lateral Movement"
reference = "https://attack.mitre.org/tactics/TA0008/"