FortiSIEM Rules

Windows: Shells Spawned by Web Servers

Rule ID


Default Status



Detects web servers that spawn shell processes which could be the result of a successfully placed web shell or another attack. This rule is adapted from







Persistence consists of techniques that adversaries use to keep access to systems across restarts, changed credentials, and other interruptions that could cut off their access. Techniques used for persistence include any access, action, or configuration changes that let them maintain their foothold on systems, such as replacing or hijacking legitimate code or adding startup code.

MITRE ATT&CK® Techniques


Server Software Component: Web Shell

Adversaries may backdoor web servers with web shells to establish persistent access to systems. A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to use the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server.



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 "\\UMWorkerProcess\.exe$|\\caddy\.exe$|\\httpd\.exe$|\\nginx\.exe$|\\php-cgi\.exe$|\\php\.exe$|\\tomcat\.exe$|\\w3wp\.exe$|\\ws_TomcatService\.exe$" OR (parentProcName REGEXP "\\java\.exe$|\\javaw\.exe$" AND parentProcName REGEXP ".*-tomcat-.*|.*\\tomcat.*") OR (parentProcName REGEXP "\\java\.exe$|\\javaw\.exe$" AND parentCommand REGEXP ".*CATALINA_HOME.*|.*catalina\.home.*|.*catalina\.jar.*")) AND procName REGEXP "\\arp\.exe$|\\at\.exe$|\\bash\.exe$|\\bitsadmin\.exe$|\\certutil\.exe$|\\cmd\.exe$|\\cscript\.exe$|\\dsget\.exe$|\\dsquery\.exe$|\\find\.exe$|\\findstr\.exe$|\\fsutil\.exe$|\\hostname\.exe$|\\ipconfig\.exe$|\\nbtstat\.exe$|\\net1\.exe$|\\net\.exe$|\\netdom\.exe$|\\netsh\.exe$|\\netstat\.exe$|\\nltest\.exe$|\\nslookup\.exe$|\\ntdutil\.exe$|\\pathping\.exe$|\\ping\.exe$|\\powershell\.exe$|\\powershell_ise\.exe$|\\pwsh\.exe$|\\qprocess\.exe$|\\query\.exe$|\\qwinsta\.exe$|\\reg\.exe$|\\rundll32\.exe$|\\sc\.exe$|\\schtasks\.exe$|\\sh\.exe$|\\systeminfo\.exe$|\\tasklist\.exe$|\\tracert\.exe$|\\ver\.exe$|\\vssadmin\.exe$|\\wevtutil\.exe$|\\whoami\.exe$|\\wmic\.exe$|\\wscript\.exe$|\\wusa\.exe$") AND ((command NOT REGEXP "Windows\\system32\\cmd\.exe /c C:\\ManageEngine\\ADManager \"Plus\\ES\\bin\\elasticsearch\.bat -Enode\.name=RMP-NODE1 -pelasticsearch-pid\.txt$") AND (command NOT REGEXP ".*sc query.*" OR command NOT REGEXP ".*ADManager Plus.*"))

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