Potential Account Takeover - Mixed Logon Types
Description
Identifies a user account (often a service account) that normally logs in with high volume using one logon type suddenly showing successful logons using a different logon type with low count. This pattern may indicate account takeover or use of stolen credentials from a new context (e.g. interactive or network logon where only batch/service was expected).
Query · esql
from logs-system.security*, logs-windows.forwarded*, winlogbeat-* metadata _id, _version, _index
| WHERE event.category == "authentication" and event.action == "logged-in" and winlog.event_id == "4624" and
event.outcome == "success" and not user.id in ("S-1-5-18", "S-1-5-19", "S-1-5-20") and
to_lower(user.name) != "administrator"
| STATS logon_count = COUNT(*), host_names = VALUES(host.name) by user.name, user.id, winlog.logon.type
| STATS
Esql.max_logon = MAX(logon_count),
Esql.min_logon = MIN(logon_count),
Esql.unique_host_count = COUNT_DISTINCT(host_names),
Esql.host_name_values = VALUES(host_names),
Esql.logon_type_values = VALUES(winlog.logon.type),
Esql.count_distinct_logon_types = COUNT_DISTINCT(winlog.logon.type) by user.name, user.id
// high count of logons is often associated with service account tied to a specific service, if observed in use with a different logon type it's suspicious
| WHERE Esql.count_distinct_logon_types >= 2 and Esql.max_logon >= 1000 and (Esql.min_logon >= 1 and Esql.min_logon <= 10) and Esql.unique_host_count >= 2
| EVAL winlog.logon.type = MV_FIRST(Esql.logon_type_values), host.name = MV_FIRST(Esql.host_name_values)
| KEEP user.name, user.id, host.name, winlog.logon.type, Esql.*
Implementation guide
Audit Logon must be enabled to generate the events used by this rule. Setup instructions: https://ela.st/audit-logon
Analyst notes
Investigating Potential Account Takeover - Mixed Logon Types
A high-volume account (e.g. service account tied to a specific logon type such as Batch or Network) that also shows successful logons with a different logon type and low count may indicate credential compromise and use from a new context (account takeover or misuse).
Possible investigation steps
- Confirm with the account owner or service owner whether the additional logon type is expected (e.g. new automation, RDP for maintenance).
- Review which logon types appear in Esql.logon_type_values and which has the low count (likely the anomalous one).
- Correlate with other alerts for the same user (e.g. logon from new source IP, password changes, MFA changes).
- Check whether the account is a known service account; if so, verify if any new scripts or systems were authorized to use it.
False positive analysis
- Legitimate expansion of use (e.g. service account also used for occasional interactive logon for troubleshooting) can trigger this. Tune thresholds (e.g. max_logon >= 1000, min_logon <= 10) or add exclusions for known service accounts with documented multi-context use.
- New scheduled tasks or automation that use a different logon type may cause a short-lived spike in the "other" logon type; review over a longer window if needed.
Response and remediation
- If takeover or misuse is confirmed: force password reset, revoke sessions, rotate service account credentials, and restrict logon type or source where possible.
- Investigate how credentials may have been compromised and address the vector.