Measurable Increase Of Successful Authentications — Sigma Rule

Rule metadata and linked tags

Author: Mark Morowczynski '@markmorow', MikeDuddington, '@dudders1', Tim Shelton. Source status: test; severity: low. Source dates: 2022-08-11 / 2022-08-18.

{
  "product": "azure",
  "service": "signinlogs"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 0901851dadde50e2796ecb449507b8d69030fadbd664512f4feb6e384b51bf4f

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Measurable Increase Of Successful Authentications
id: 67d5f8fc-8325-44e4-8f5f-7c0ac07cb5ae
status: test
description: Detects when successful sign-ins increased by 10% or greater.
references:
    - https://learn.microsoft.com/en-us/entra/architecture/security-operations-user-accounts#monitoring-for-successful-unusual-sign-ins
author: Mark Morowczynski '@markmorow', MikeDuddington, '@dudders1', Tim Shelton
date: 2022-08-11
modified: 2022-08-18
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.initial-access
    - attack.stealth
    - attack.t1078
logsource:
    product: azure
    service: signinlogs
detection:
    selection:
        Status: Success
        Count: "<10%"
    condition: selection
falsepositives:
    - Increase of users in the environment
level: low

Original YAML and metadata in JSON

False positives

• Increase of users in the environment

Source references

• https://learn.microsoft.com/en-us/entra/architecture/security-operations-user-accounts#monitoring-for-successful-unusual-sign-ins