Detection rules › Sigma

Measurable Increase Of Successful Authentications

Status
test
Severity
low
Log source
product azure, service signinlogs
Author
Mark Morowczynski '@markmorow', MikeDuddington, '@dudders1', Tim Shelton
Source
github.com/SigmaHQ/sigma

Detects when successful sign-ins increased by 10% or greater.

MITRE ATT&CK coverage

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

Rule body yaml

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

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Status: Success
    Count: "<10%"

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
Counteq
  • <10%
Statuseq
  • Success