Azure secure score block legacy authentication

Status: available
Severity: high
Time window: 6h
Source: github.com/Azure/Azure-Sentinel

'This query searches for most compromising sign-in attempts come from legacy authentication. Older office clients such as Office 2010 do not support modern authentication and use legacy protocols such as IMAP, SMTP, and POP3. Legacy authentication does not support multi-factor authentication (MFA). Even if an MFA policy is configured in your environment, bad actors can bypass these enforcements through legacy protocols.'

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1212` Exploitation for Credential Access, `T1556` Modify Authentication Process

Rule body kusto

id: C27BB559-28C5-4924-A7DA-3BF04CD02C8F
name: Azure secure score block legacy authentication
description: |
  'This query searches for most compromising sign-in attempts come from legacy authentication. 
   Older office clients such as Office 2010 do not support modern authentication and use legacy protocols such as IMAP, SMTP, and POP3. 
   Legacy authentication does not support multi-factor authentication (MFA).
   Even if an MFA policy is configured in your environment, bad actors can bypass these enforcements through legacy protocols.'
severity: High
status: Available
requiredDataConnectors:
  - connectorId: SenservaPro
    dataTypes:
      - SenservaPro_CL
queryFrequency: 6h
queryPeriod: 6h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CredentialAccess
relevantTechniques:
  - T1212
  - T1556
query: |
  SenservaPro_CL
  | where ControlName_s == 'AzureSecureScoreBlockLegacyAuthentication'
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: ControlName_s
      - identifier: AadTenantId
        columnName: TenantId
      - identifier: DisplayName
        columnName: TenantDisplayName_s 
  - entityType: SecurityGroup
    fieldMappings:
      - identifier: DistinguishedName
        columnName: Group_s
  - entityType: AzureResource
    fieldMappings:
      - identifier: ResourceId
        columnName: SourceSystem 
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: `source`

SenservaPro_CL

Stage 2: `where`

| where ControlName_s == 'AzureSecureScoreBlockLegacyAuthentication'

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.

Field	Kind	Values
`ControlName_s`	eq	`AzureSecureScoreBlockLegacyAuthentication` transforms: `cased`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Azure secure score block legacy authentication

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: `source`

Stage 2: `where`

Indicators

Keyboard shortcuts

Search operators

Azure secure score block legacy authentication

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Stage 1: source

Stage 2: where

Indicators

Stage 1: `source`

Stage 2: `where`