Identifies multiple logon failures followed by a successful one from the same source address. 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
Risk score: 47
Runs every: 5 minutes
Maximum alerts per execution: 100
- Threat Detection
- Credential Access
Added (Elastic Stack release): 8.5.0
Rule authors: Elastic
Rule license: Elastic License v2
## 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).
sequence by host.id, source.ip with maxspan=5s [authentication where event.action == "logon-failed" and /* event 4625 need to be logged */ winlog.logon.type : "Network" and source.ip != null and source.ip != "127.0.0.1" and source.ip != "::1" and not user.name : ("ANONYMOUS LOGON", "-", "*$") and not user.domain == "NT AUTHORITY" and /* noisy failure status codes often associated to authentication misconfiguration */ not winlog.event_data.Status : ("0xC000015B", "0XC000005E", "0XC0000133", "0XC0000192")] with runs=5 [authentication where event.action == "logged-in" and /* event 4624 need to be logged */ winlog.logon.type : "Network" and source.ip != null and source.ip != "127.0.0.1" and source.ip != "::1" and not user.name : ("ANONYMOUS LOGON", "-", "*$") and not user.domain == "NT AUTHORITY"]