Accessing Outlook Data Files

[metadata]
creation_date = "2023/08/21"
integration = ["endpoint", "windows", "system"]
maturity = "production"
updated_date = "2026/03/24"

[rule]
author = ["Elastic"]
building_block_type = "default"
description = """
Identifies commands containing references to Outlook data files extensions, which can potentially indicate the search,
access, or modification of these files.
"""
from = "now-119m"
index = [
    "endgame-*",
    "logs-endpoint.events.process-*",
    "logs-system.security*",
    "logs-windows.sysmon_operational-*",
    "winlogbeat-*",
]
interval = "60m"
language = "eql"
license = "Elastic License v2"
name = "Accessing Outlook Data Files"
risk_score = 21
rule_id = "2e311539-cd88-4a85-a301-04f38795007c"
severity = "low"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Collection",
    "Data Source: Elastic Defend",
    "Rule Type: BBR",
    "Data Source: Sysmon",
    "Data Source: Elastic Endgame",
    "Data Source: Windows Security Event Logs",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where host.os.type == "windows" and event.type == "start" and process.args : ("*.ost", "*.pst") and
  not process.name : "outlook.exe" and
  not (
        process.name : "rundll32.exe" and
        process.args : "*davclnt.dll,DavSetCookie*"
  )
'''


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

[[rule.threat.technique]]
id = "T1005"
name = "Data from Local System"
reference = "https://attack.mitre.org/techniques/T1005/"

[[rule.threat.technique]]
id = "T1114"
name = "Email Collection"
reference = "https://attack.mitre.org/techniques/T1114/"

[[rule.threat.technique.subtechnique]]
id = "T1114.001"
name = "Local Email Collection"
reference = "https://attack.mitre.org/techniques/T1114/001/"

[rule.threat.tactic]
id = "TA0009"
name = "Collection"
reference = "https://attack.mitre.org/tactics/TA0009/"