FortiSIEM Rules

Windows: Jlaive Usage For Assembly Execution In-Memory

Rule ID


Default Status



Detects the use of Jlaive to execute assemblies in a copied PowerShell. This rule is adapted from







Execution consists of techniques that result in adversary-controlled code running on a local or remote system. Techniques that run malicious code are often paired with techniques from all other tactics to achieve broader goals, like exploring a network or stealing data. For example, an adversary might use a remote access tool to run a PowerShell script that does Remote System Discovery.

MITRE ATT&CK® Techniques


Command and Scripting Interpreter: Windows Command Shell

Adversaries may abuse the Windows command shell for execution. Batch files (ex: .bat or .cmd) also provide the shell with a list of sequential commands to run, as well as normal scripting operations such as conditionals and loops. Adversaries may leverage cmd.exe to execute various commands and payloads.



Data Source

Windows Sysmon via FortiSIEM Agent



Remediation Guidance

No remediation guidance specified

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: Filter

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="Win-Sysmon-1-Create-Process" AND parentProcName REGEXP "\\cmd\.exe$" AND parentCommand REGEXP "\.bat$" AND command REGEXP ".*\.bat\.exe.*" AND ((procName REGEXP "\\xcopy\.exe$" AND command REGEXP ".*powershell\.exe.*") OR (procName REGEXP "\\xcopy\.exe$" AND command REGEXP ".*pwsh\.exe.*") OR (procName REGEXP "\\attrib\.exe$" AND command REGEXP ".*\+s.*" AND command REGEXP ".*\+h.*"))

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

command = Filter.command,
hostName = Filter.hostName,
parentCommand = Filter.parentCommand,
parentProcName = Filter.parentProcName,
procName = Filter.procName