Windows: Creation of an Executable by an Executable

Rule ID

PH_Rule_SIGMA_852

Default Status

Enabled

Description

Detects the creation of an executable by another executable. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_susp_dropper.yml

Severity

MITRE ATT&CK® Tactics

Resource Development

Resource Development consists of techniques that involve adversaries creating, purchasing, or compromising/stealing resources that can be used to support targeting. Such resources include infrastructure, accounts, or capabilities. These resources can be leveraged by the adversary to aid in other phases of the adversary lifecycle, such as using purchased domains to support Command and Control, email accounts for phishing as a part of Initial Access, or stealing code signing certificates to help with Defense Evasion.

https://attack.mitre.org/tactics/TA0042

MITRE ATT&CK® Techniques

T1587.001

Develop Capabilities: Malware

Before compromising a victim, adversaries may develop malware and malware components that can be used during targeting. Building malicious software can include the development of payloads, droppers, post-compromise tools, backdoors, packers, C2 protocols, and the creation of infected removable media. Adversaries may develop malware to support their operations, creating a means for maintaining control of remote machines, evading defenses, and executing post-compromise behaviors.

https://attack.mitre.org/techniques/T1587/001

Impacts

Server

Data Source

Windows Sysmon via FortiSIEM Agent

Detection

Correlation

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.

Filter

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-11-FileCreate" AND (procName REGEXP "\.exe$" AND fileName REGEXP "\.exe$") AND ((procName NOT IN ("C:\\WINDOWS\\system32\\Dism.exe","C:\\WINDOWS\\system32\\dxgiadaptercache.exe","C:\\Windows\\System32\\msiexec.exe","C:\\Windows\\System32\\wuauclt.exe","C:\\Windows\\explorer.exe","C:\\Windows\\system32\\cleanmgr.exe")) AND (procName!="C:\\WINDOWS\\system32\\svchost.exe" OR fileName NOT REGEXP "^C:\\Windows\\SoftwareDistribution\\Download\\") AND (procName!="C:\\Windows\\system32\\svchost.exe" OR fileName NOT REGEXP ".*:\\WUDownloadCache\\.*" OR fileName NOT REGEXP ".*\\WindowsUpdateBox\.exe.*") AND (procName NOT REGEXP "^C:\\WINDOWS\\SoftwareDistribution\\Download\\" OR procName NOT REGEXP "\\WindowsUpdateBox\.Exe$" OR fileName NOT REGEXP "^C:\\\$WINDOWS\.~BT\\Sources\\") AND (procName NOT REGEXP "^C:\\Windows\\WinSxS\\" OR procName NOT REGEXP "\\TiWorker\.exe$") AND (procName NOT REGEXP "^C:\\Program Files \(x86\)\\|^C:\\Program Files\\" AND fileName NOT REGEXP "^C:\\Program Files \(x86\)\\|^C:\\Program Files\\") AND (procName NOT REGEXP "^C:\\Program Files\\Windows Defender\\|^C:\\ProgramData\\Microsoft\\Windows Defender\\") AND (fileName NOT REGEXP ".*\\Microsoft\\WindowsApps\\.*") AND (procName NOT REGEXP "\\AppData\\Local\\Microsoft\\Teams\\Update\.exe$" OR fileName NOT REGEXP "\\AppData\\Local\\Microsoft\\SquirrelTemp\\tempb\\$|\\AppData\\Local\\Microsoft\\Teams\\stage\\Squirrel\.exe$|\\AppData\\Local\\Microsoft\\Teams\\stage\\Teams\.exe$") AND (procName NOT REGEXP "^C:\\Windows\\Microsoft\.NET\\Framework\\" OR procName NOT REGEXP "\\mscorsvw\.exe$" OR fileName NOT REGEXP "^C:\\Windows\\assembly\\NativeImages_") AND (procName NOT REGEXP ".*\\AppData\\Local\\.*" OR procName NOT REGEXP "\\Microsoft VS Code\\Code\.exe$" OR fileName NOT REGEXP ".*\\\.vscode\\extensions\\.*") AND (procName NOT REGEXP "\\AppData\\Local\\GitHubDesktop\\Update\.exe$" OR fileName NOT REGEXP ".*\\AppData\\Local\\SquirrelTemp\\.*") AND (fileName NOT REGEXP "^C:\\WINDOWS\\TEMP\\"))

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

fileName,hostName,procName

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

fileName = Filter.fileName,
hostName = Filter.hostName,
procName = Filter.procName

FortiSIEM Rules