Privileged Account Brute Forceedit

Identifies multiple consecutive logon failures targeting an Admin account from the same source address and within a short time interval. Adversaries will often brute force login attempts across multiple users with a common or known password, in an attempt to gain access to accounts.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-system.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100



  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Credential Access

Version: 1

Added (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guideedit

## Triage and analysis

#### Possible investigation steps

- Investigate the logon failure reason code and the targeted user names.
- Investigate the source IP address of the failed Network Logon attempts.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Identify the source and the target computer and their roles in the IT environment.

### False positive analysis

- Authentication misconfiguration or obsolete credentials.
- Service account password expired.
- Trust relationship between the primary domain and the trusted domain issue.
- Infrastructure or availability issue.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- If the host is a domain controller (DC):
  - Activate your incident response plan for total Active Directory compromise.
  - Review the privileges assigned to users that can access the DCs, to ensure that the least privilege principle is
  being followed and to reduce the attack surface.
- Isolate the involved hosts to prevent further post-compromise behavior.
- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
systems, and web services.
- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
malware components.
- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
mean time to respond (MTTR).

Rule queryedit

sequence by, source.ip with maxspan=10s [authentication
where event.action == "logon-failed" and winlog.logon.type :
"Network" and source.ip != null and source.ip != "" and
source.ip != "::1" and : "*admin*" and /* noisy failure
status codes often associated to authentication misconfiguration */
not winlog.event_data.Status : ("0xC000015B", "0XC000005E",
"0XC0000133", "0XC0000192")] with runs=5

Threat mappingedit