[metadata]
creation_date = "2020/11/20"
maturity = "production"
updated_date = "2020/12/15"

[rule]
author = ["Elastic"]
description = """
Identifies when guest access is enabled in Microsoft Teams. Guest access in Teams allows people outside the organization
to access teams and channels. An adversary may enable guest access to maintain persistence in an environment.
"""
false_positives = [
    """
    Teams guest access may be enabled by a system or network administrator. Verify that the configuration change was
    expected. Exceptions can be added to this rule to filter expected behavior.
    """,
]
from = "now-30m"
index = ["filebeat-*", "logs-o365*"]
language = "kuery"
license = "Elastic License"
name = "Microsoft 365 Teams Guest Access Enabled"
note = "The Microsoft 365 Fleet integration or Filebeat module must be enabled to use this rule."
references = [
    "https://docs.microsoft.com/en-us/powershell/module/skype/get-csteamsclientconfiguration?view=skype-ps",
]
risk_score = 47
rule_id = "5e552599-ddec-4e14-bad1-28aa42404388"
severity = "medium"
tags = ["Elastic", "Cloud", "Microsoft 365", "Continuous Monitoring", "SecOps", "Configuration Audit"]
type = "query"

query = '''
event.dataset:o365.audit and event.provider:(SkypeForBusiness or MicrosoftTeams) and
event.category:web and event.action:"Set-CsTeamsClientConfiguration" and
o365.audit.Parameters.AllowGuestUser:True and event.outcome:success
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1098"
name = "Account Manipulation"
reference = "https://attack.mitre.org/techniques/T1098/"


[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"

