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Attack: Event Triggered Execution

Adversaries may establish persistence and/or elevate privileges using system mechanisms that trigger execution based on specific events. Various operating systems have means to monitor and subscribe to events such as logons or other user activity such as running specific applications/binaries. Cloud environments may also support various functions and services that monitor and can be invoked in response to specific cloud events.(Citation: Backdooring an AWS account)(Citation: Varonis Power Automate Data Exfiltration)(Citation: Microsoft DART Case Report 001)

Adversaries may abuse these mechanisms as a means of maintaining persistent access to a victim via repeatedly executing malicious code. After gaining access to a victim system, adversaries may create/modify event triggers to point to malicious content that will be executed whenever the event trigger is invoked.(Citation: FireEye WMI 2015)(Citation: Malware Persistence on OS X)(Citation: amnesia malware)

Since the execution can be proxied by an account with higher permissions, such as SYSTEM or service accounts, an adversary may be able to abuse these triggered execution mechanisms to escalate their privileges.

MITRE

Tactic

technique

Test : Persistence with Custom AutodialDLL

OS

Description:

The DLL pointed to by the AutodialDLL registry key is loaded every time a process connects to the internet. Attackers can gain persistent code execution by setting this key to a DLL of their choice.

The sample dll provided, AltWinSock2DLL, will launch the notepad process. Starting and stopping a web browser such as MS Edge or Chrome should result in the dll executing. Blog

Executor

powershell

Sigma Rule

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