FortiSIEM Rules

Outbreak: Kaseya REvil Ransomware File Activity Detected on Host

Rule ID


Default Status



A Fortinet product has detected a host with malware known to be associated with REvil Ransomware activity. These indicators were seen during the Kaseya VSA Supply Chain Attack.






Initial Access

Initial Access consists of techniques that use various entry vectors to gain their initial foothold within a network. Techniques used to gain a foothold include targeted spearphishing and exploiting weaknesses on public-facing web servers. Footholds gained through initial access may allow for continued access, like valid accounts and use of external remote services, or may be limited-use due to changing passwords.

MITRE ATT&CK® Techniques


Supply Chain Compromise: Compromise Software Supply Chain

Adversaries may manipulate application software prior to receipt by a final consumer for the purpose of data or system compromise. Supply chain compromise of software can take place in a number of ways, including manipulation of the application source code, manipulation of the update/distribution mechanism for that software, or replacing compiled releases with a modified version. Targeting may be specific to a desired victim set or may be distributed to a broad set of consumers but only move on to additional tactics on specific victims.



Data Source

FortiClient via Syslog



Remediation Guidance

Check if the source is patched for the CVE associated with the event. If yes then remove the host from the network and patch immediately. If host is not scanned then determine if the host is running the affected version of the application. If yes then patch immediately, else it is likely a false positive.

Time Window

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

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.


SubPattern Definitions

SubPattern Name: revil

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_FortiClient_AV_Detected)  AND ( virusName IN ("W32/Sodinokibi.8859!tr.ransom","W32/Sodinokibi.5421!tr.ransom","W32/Sodinokibi.EAD4!tr.ransom")  OR  attackName IN ("W32/Sodinokibi.8859!tr.ransom","W32/Sodinokibi.5421!tr.ransom","W32/Sodinokibi.EAD4!tr.ransom"))

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(*) >= 1

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