FortiSIEM Rules

Multiple Logon Failures: Same Src and Multiple Dest

Rule ID


Default Status



Detects the same source having excessive logon failures at more than 10 distinct hosts






Credential Access

Credential Access consists of techniques for stealing credentials like account names and passwords. Techniques used to get credentials include keylogging or credential dumping. Using legitimate credentials can give adversaries access to systems, make them harder to detect, and provide the opportunity to create more accounts to help achieve their goals.

MITRE ATT&CK® Techniques


Brute Force: Password Guessing

Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.



Data Source

FortiGate via Syslog, FortiProxy via Syslog, Juniper JunOS via Syslog, Juniper SRX Via Syslog, Juniper SSG via Syslog, Pulse Secure via Syslog, Hillstone Firewall Via Syslog, Cisco ASA via Syslog, Cisco IOS Via Syslog, WatchGuard via Syslog, Sophos Firewall via Syslog, SonicOS via Syslog, Riverbed via Syslog, NetScaler via Syslog, HP Procurve via Syslog, FortiWeb via Syslog, BlueCoat via Syslog, Windows via OMI or FortiSIEM Agent, Linux via Syslog, VMware NSX via Syslog, FortiSIEM via Syslog, IBM AIX via Syslog, AWS CloudTrail via AWS_CLOUDTRAIL, Office 365 via Management Activity API



Remediation Guidance

Identify the source of the incident and the user and make sure that it is a legitimate attempt to log on to the system. Make sure it is not a cached credential from another system while the primary user has changed credential. Make sure there are no other incidents from the source host that may indicate malware trying to gain access to other systems. Make sure there are no vulnerabilities on the source and destination hosts.

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

3600 seconds

Trigger Conditions

If the following defined pattern/s occur within a 3600 second time window.


SubPattern Definitions

SubPattern Name: PasswordScan_ManyDest

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

eventType IN (Group@PH_SYS_EVENT_HostLogonFailure)

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID


Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT (DISTINCT destIpAddr) >= 10

Incident Attribute Mapping

This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.

The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern

 srcIpAddr = PasswordScan_ManyDest.srcIpAddr,
 incidentCount = PasswordScan_ManyDest.COUNT (DISTINCT destIpAddr)