Azure SignIn via Legacy Authentication Protocol

Severity: medium
Log types: Azure.Audit
Reference: https://learn.microsoft.com/en-us/azure/active-directory/reports-monitoring/workbook-legacy-authentication
Source: github.com/panther-labs/panther-analysis

This detection looks for Successful Logins that have used legacy authentication protocols

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Anomalous sign-in location by user account and authenticating application (Kusto)
Anomalous Single Factor Signin (Kusto)
Authentications of Privileged Accounts Outside of Expected Controls (Kusto)
Azure Many Failed SignIns (Panther)
Azure Portal sign in from another Azure Tenant (Kusto)
Azure Service Principal Sign-In Followed by Arc Cluster Credential Access (Elastic)
Detect non-admin requesting token for admin applications (Kusto)
Discovery Using AzureHound (Sigma)

Rule body yaml

AnalysisType: rule
Filename: azure_legacyauth.py
RuleID: "Azure.Audit.LegacyAuth"
DisplayName: "Azure SignIn via Legacy Authentication Protocol"
Enabled: true
Threshold: 1
DedupPeriodMinutes: 10
LogTypes:
  - Azure.Audit
Severity: Medium
Description: >
  This detection looks for Successful Logins that have used legacy authentication protocols
Reference: https://learn.microsoft.com/en-us/azure/active-directory/reports-monitoring/workbook-legacy-authentication
Runbook: >
  Based on Microsoft's analysis more than 97 percent of credential stuffing attacks use legacy authentication and more than 99 percent
  of password spray attacks use legacy authentication protocols. These attacks would stop with basic authentication disabled or blocked.
  see https://learn.microsoft.com/en-us/azure/active-directory/conditional-access/block-legacy-authentication

  If you are aware of this Legacy Auth need, and need to continue using this mechanism, add the principal name to KNOWN_EXCEPTIONS.
  The Reference link contains additional material hosted on Microsoft.com
SummaryAttributes:
  - properties:ServicePrincipalName
  - properties:UserPrincipalName
  - properties:ipAddress
Tests:
  - Name: Failed Sign-In
    ExpectedResult: False
    Log:
      {
        "calleripaddress": "12.12.12.12",
        "category": "ServicePrincipalSignInLogs",
        "correlationid": "e1f237ef-6548-4172-be79-03818c04c06e",
        "durationms": 0,
        "Level": "4",
        "location": "IE",
        "operationname": "Sign-in activity",
        "operationversion": 1,
        "p_event_time": "2023-07-26 23:00:20.889",
        "p_log_type": "Azure.Audit",
        "properties":
          {
            "appId": "cfceb902-8fab-4f8c-88ba-374d3c975c3a",
            "authenticationProcessingDetails":
              [{ "key": "Azure AD App Authentication Library", "value": "" }],
            "authenticationProtocol": "none",
            "clientCredentialType": "none",
            "conditionalAccessStatus": "notApplied",
            "correlationId": "5889315c-c4ac-4807-99da-e17417eae786",
            "createdDateTime": "2023-07-26 22:58:30.983201900",
            "crossTenantAccessType": "none",
            "flaggedForReview": false,
            "id": "36658c78-02d9-4d8f-84ee-5ca4a3fdefef",
            "incomingTokenType": "none",
            "ipAddress": "12.12.12.12",
            "isInteractive": false,
            "isTenantRestricted": false,
            "location":
              {
                "city": "Dublin",
                "countryOrRegion": "IE",
                "geoCoordinates":
                  {
                    "latitude": 51.35555555555555,
                    "longitude": -5.244444444444444,
                  },
                "state": "Dublin",
              },
            "managedIdentityType": "none",
            "processingTimeInMilliseconds": 0,
            "resourceDisplayName": "Azure Storage",
            "resourceId": "037694de-8c7d-498d-917d-edb650090fa5",
            "resourceServicePrincipalId": "a225221f-8cc5-411a-9cc7-5e1394b8a5b8",
            "riskDetail": "none",
            "riskLevelAggregated": "low",
            "riskLevelDuringSignIn": "low",
            "riskState": "none",
            "servicePrincipalId": "b1c34143-e405-4058-8e29-84596ad737b8",
            "servicePrincipalName": "some-service-principal",
            "status": { "errorCode": 7000215 },
            "tokenIssuerType": "AzureAD",
            "uniqueTokenIdentifier": "NDDDDDDDDDDDDDDDDDD_DD",
          },
        "resourceid": "/tenants/c0dd2fa0-71be-4df8-b2a6-24cee7de069a/providers/Microsoft.aadiam",
        "resultsignature": "None",
        "resulttype": 7000215,
        "tenantid": "a2aa49aa-2c0c-49d2-af87-f402c421df0b",
        "time": "2023-07-26 23:00:20.889",
      }
  - Name: Sign-In with legacy auth
    ExpectedResult: True
    Log:
      {
        "calleripaddress": "1.2.3.4",
        "category": "SignInLogs",
        "correlationid": "1043d312-230b-4f85-89de-2438df7ad2e9",
        "durationms": 0,
        "identity": "Some Identity",
        "Level": "4",
        "location": "US",
        "operationname": "Sign-in activity",
        "operationversion": 1,
        "p_event_time": "2023-07-21 05:05:12.056",
        "p_log_type": "Azure.Audit",
        "properties":
          {
            "appDisplayName": "Office 365 Exchange Online",
            "appId": "975c4feb-8c6b-4ed8-82e2-f0952ecc64d4",
            "appliedConditionalAccessPolicies": [],
            "authenticationContextClassReferences": [],
            "authenticationDetails":
              [
                {
                  "authenticationMethod": "Password",
                  "authenticationMethodDetail": "Password in the cloud",
                  "authenticationStepDateTime": "2023-01-11T11:11:11",
                  "authenticationStepRequirement": "",
                  "authenticationStepResultDetail": "Correct password",
                  "succeeded": true,
                },
              ],
            "authenticationProcessingDetails": [],
            "authenticationProtocol": "rpoc",
            "authenticationRequirement": "singleFactorAuthentication",
            "authenticationRequirementPolicies": [],
            "authenticationStrengths": [],
            "autonomousSystemNumber": 1234,
            "clientAppUsed": "Authenticated SMTP",
            "clientCredentialType": "clientAssertion",
            "conditionalAccessStatus": "notApplied",
            "correlationId": "9d5f7dd3-46a7-475a-9cc3-96160551ce49",
            "createdDateTime": "2023-07-21 05:03:52.160562400",
            "crossTenantAccessType": "none",
            "deviceDetail":
              { "deviceId": "", "displayName": "", "operatingSystem": "MacOs" },
            "flaggedForReview": false,
            "homeTenantId": "4328f0a8-06da-4457-b0d0-2c8e115e52cc",
            "id": "d9ae0e20-c959-42a3-ba74-00f59ac9f6c6",
            "incomingTokenType": "none",
            "ipAddress": "12.12.12.12",
            "isInteractive": true,
            "isTenantRestricted": false,
            "location":
              {
                "city": "Springfield",
                "countryOrRegion": "US",
                "geoCoordinates":
                  {
                    "latitude": 34.55555555555555,
                    "longitude": -74.4444444444444,
                  },
                "state": "Virginia",
              },
            "mfaDetail": {},
            "networkLocationDetails": [],
            "originalRequestId": "51755ad1-bc0d-4694-acb2-a21f054869ab",
            "privateLinkDetails": {},
            "processingTimeInMilliseconds": 343,
            "resourceDisplayName": "Office 365 Exchange Online",
            "resourceId": "b54c474b-4d74-4920-b0c3-7a8d2f2c4e95",
            "resourceServicePrincipalId": "d8f787f8-7f22-40d4-b057-6fc59c49ca43",
            "resourceTenantId": "fc66a38e-bcba-4fe9-b2de-c67918514cc5",
            "riskDetail": "none",
            "riskEventTypes": [],
            "riskEventTypes_v2": [],
            "riskLevelAggregated": "none",
            "riskLevelDuringSignIn": "none",
            "riskState": "none",
            "rngcStatus": 0,
            "servicePrincipalId": "",
            "sessionLifetimePolicies": [],
            "ssoExtensionVersion": "",
            "status":
              {
                "additionalDetails": "MFA requirement satisfied by claim in the token",
                "errorCode": 0,
              },
            "tenantId": "237c496d-1ca2-4b13-aa0f-69e44d745a27",
            "tokenIssuerName": "",
            "tokenIssuerType": "AzureAD",
            "uniqueTokenIdentifier": "hhhhhhhhhhhhhhhhhhhhhh",
            "userAgent": "BAV2ROPC",
            "userDisplayName": "A User Display Name",
            "userId": "8105c513-d24b-4b8d-9035-f8d48854d703",
            "userPrincipalName": "eve@lexcorp.com",
            "userType": "Member",
          },
        "resourceid": "/tenants/ef3a1b35-97d6-474b-a9de-94d21d4ee71b/providers/Microsoft.aadiam",
        "resultsignature": "None",
        "resulttype": 0,
        "tenantid": "c5fd010a-2972-4be2-9c67-986ceca2a042",
        "time": "2023-07-21 05:05:12.056",
      }
  - Name: Sign-In with legacy auth, KNOWN_EXCEPTION
    ExpectedResult: False
    Mocks:
      - objectName: KNOWN_EXCEPTIONS
        returnValue: >-
          [
            "homer.simpson@springfield.org"
          ]
    Log:
      {
        "calleripaddress": "173.53.70.163",
        "category": "SignInLogs",
        "correlationid": "1043d312-230b-4f85-89de-2438df7ad2e9",
        "durationms": 0,
        "identity": "Some Identity",
        "Level": "4",
        "location": "US",
        "operationname": "Sign-in activity",
        "operationversion": 1,
        "p_event_time": "2023-07-21 05:05:12.056",
        "p_log_type": "Azure.Audit",
        "properties":
          {
            "appDisplayName": "Office 365 Exchange Online",
            "appId": "975c4feb-8c6b-4ed8-82e2-f0952ecc64d4",
            "appliedConditionalAccessPolicies": [],
            "authenticationContextClassReferences": [],
            "authenticationDetails":
              [
                {
                  "authenticationMethod": "Password",
                  "authenticationMethodDetail": "Password in the cloud",
                  "authenticationStepDateTime": "2023-01-11T11:11:11",
                  "authenticationStepRequirement": "",
                  "authenticationStepResultDetail": "Correct password",
                  "succeeded": true,
                },
              ],
            "authenticationProcessingDetails": [],
            "authenticationProtocol": "rpoc",
            "authenticationRequirement": "singleFactorAuthentication",
            "authenticationRequirementPolicies": [],
            "authenticationStrengths": [],
            "autonomousSystemNumber": 1234,
            "clientAppUsed": "Authenticated SMTP",
            "clientCredentialType": "clientAssertion",
            "conditionalAccessStatus": "notApplied",
            "correlationId": "9d5f7dd3-46a7-475a-9cc3-96160551ce49",
            "createdDateTime": "2023-07-21 05:03:52.160562400",
            "crossTenantAccessType": "none",
            "deviceDetail":
              { "deviceId": "", "displayName": "", "operatingSystem": "MacOs" },
            "flaggedForReview": false,
            "homeTenantId": "4328f0a8-06da-4457-b0d0-2c8e115e52cc",
            "id": "d9ae0e20-c959-42a3-ba74-00f59ac9f6c6",
            "incomingTokenType": "none",
            "ipAddress": "12.12.12.12",
            "isInteractive": true,
            "isTenantRestricted": false,
            "location":
              {
                "city": "Springfield",
                "countryOrRegion": "US",
                "geoCoordinates":
                  {
                    "latitude": 34.55555555555555,
                    "longitude": -74.4444444444444,
                  },
                "state": "Virginia",
              },
            "mfaDetail": {},
            "networkLocationDetails": [],
            "originalRequestId": "51755ad1-bc0d-4694-acb2-a21f054869ab",
            "privateLinkDetails": {},
            "processingTimeInMilliseconds": 343,
            "resourceDisplayName": "Office 365 Exchange Online",
            "resourceId": "b54c474b-4d74-4920-b0c3-7a8d2f2c4e95",
            "resourceServicePrincipalId": "d8f787f8-7f22-40d4-b057-6fc59c49ca43",
            "resourceTenantId": "fc66a38e-bcba-4fe9-b2de-c67918514cc5",
            "riskDetail": "none",
            "riskEventTypes": [],
            "riskEventTypes_v2": [],
            "riskLevelAggregated": "none",
            "riskLevelDuringSignIn": "none",
            "riskState": "none",
            "rngcStatus": 0,
            "servicePrincipalId": "",
            "sessionLifetimePolicies": [],
            "ssoExtensionVersion": "",
            "status":
              {
                "additionalDetails": "MFA requirement satisfied by claim in the token",
                "errorCode": 0,
              },
            "tenantId": "237c496d-1ca2-4b13-aa0f-69e44d745a27",
            "tokenIssuerName": "",
            "tokenIssuerType": "AzureAD",
            "uniqueTokenIdentifier": "hhhhhhhhhhhhhhhhhhhhhh",
            "userAgent": "BAV2ROPC",
            "userDisplayName": "A User Display Name",
            "userId": "8105c513-d24b-4b8d-9035-f8d48854d703",
            "userPrincipalName": "homer.simpson@springfield.org",
            "userType": "Member",
          },
        "resourceid": "/tenants/ef3a1b35-97d6-474b-a9de-94d21d4ee71b/providers/Microsoft.aadiam",
        "resultsignature": "None",
        "resulttype": 0,
        "tenantid": "c5fd010a-2972-4be2-9c67-986ceca2a042",
        "time": "2023-07-21 05:05:12.056",
      }

Detection logic

Condition

operationName eq "Sign-in activity"
properties.userAgent in ["BAV2ROPC", "CBAInPROD"]
properties.status.errorCode eq "0"

This rule also runs imperative logic the parser cannot express as a filter; the conditions above are the structured part it could extract.

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
`operationName`	eq	`Sign-in activity`
`properties.status.errorCode`	eq	`0`
`properties.userAgent`	in	`BAV2ROPC` `CBAInPROD`

`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)