Server Installed Software Change

Rule ID

PH_Rule_Change_7

Default Status

Enabled

Description

Detects that a new software has been installed on a server or an existing software has been deleted.

Severity

MITRE ATT&CK® Tactics

Defense Evasion

Defense Evasion consists of techniques that adversaries use to avoid detection throughout their compromise. Techniques used for defense evasion include uninstalling/disabling security software or obfuscating/encrypting data and scripts. Adversaries also leverage and abuse trusted processes to hide and masquerade their malware. Other tactics’ techniques are cross-listed here when those techniques include the added benefit of subverting defenses.

https://attack.mitre.org/tactics/TA0005

MITRE ATT&CK® Techniques

T1218.001

Signed Binary Proxy Execution: Compiled HTML File

Adversaries may abuse Compiled HTML files (.chm) to conceal malicious code. CHM files are commonly distributed as part of the Microsoft HTML Help system. A custom CHM file containing embedded payloads could be delivered to a victim then triggered by User Execution.

https://attack.mitre.org/techniques/T1218/001

Impacts

Server

Data Source

Windows via FortiSIEM Agent, Linux via SNMP

Detection

Correlation

Remediation Guidance

Make sure it is an authorized change

Time Window

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

1800 seconds

Trigger Conditions

If the following defined pattern/s occur within a 1800 second time window.

delta

SubPattern Definitions

SubPattern Name: delta

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 = "PH_DEV_MON_CHANGE_INST_SW" AND hostIpAddr IN (Group@PH_SYS_DEVICE_Server)

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

hostIpAddr,hostName,addedItem ,deletedItem

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

hostIpAddr = delta.hostIpAddr,
 hostName = delta.hostName,
 addedItem = delta.addedItem,
 deletedItem = delta.deletedItem

FortiSIEM Rules