detection.wiki

Detection rules › Sigma

Suspicious Browser Activity

Status
test
Severity
high
Log source
product azure, service riskdetection
Author
Mark Morowczynski '@markmorow', Gloria Lee, '@gleeiamglo'
Source
github.com/SigmaHQ/sigma

Indicates anomalous behavior based on suspicious sign-in activity across multiple tenants from different countries in the same browser

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1078 Valid Accounts
PersistenceT1078 Valid Accounts
Privilege EscalationT1078 Valid Accounts
StealthT1078 Valid Accounts

Rule body yaml

title: Suspicious Browser Activity
id: 944f6adb-7a99-4c69-80c1-b712579e93e6
status: test
description: Indicates anomalous behavior based on suspicious sign-in activity across multiple tenants from different countries in the same browser
references:
    - https://learn.microsoft.com/en-us/entra/id-protection/concept-identity-protection-risks#suspicious-browser
    - https://learn.microsoft.com/en-us/entra/architecture/security-operations-user-accounts#unusual-sign-ins
author: Mark Morowczynski '@markmorow', Gloria Lee, '@gleeiamglo'
date: 2023-09-03
tags:
    - attack.stealth
    - attack.t1078
    - attack.persistence
    - attack.privilege-escalation
    - attack.initial-access
logsource:
    product: azure
    service: riskdetection
detection:
    selection:
        riskEventType: 'suspiciousBrowser'
    condition: selection
falsepositives:
    - We recommend investigating the sessions flagged by this detection in the context of other sign-ins from the user.
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    riskEventType: 'suspiciousBrowser'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
riskEventTypeeq
  • suspiciousBrowser