PSAsyncShell - Asynchronous TCP Reverse Shell

Status: test
Severity: high
Log source: category ps_script, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the use of PSAsyncShell an Asynchronous TCP Reverse Shell written in powershell

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

title: PSAsyncShell - Asynchronous TCP Reverse Shell
id: afd3df04-948d-46f6-ae44-25966c44b97f
status: test
description: Detects the use of PSAsyncShell an Asynchronous TCP Reverse Shell written in powershell
references:
    - https://github.com/JoelGMSec/PSAsyncShell
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-10-04
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains: 'PSAsyncShell'
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ScriptBlockText|contains: 'PSAsyncShell'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ScriptBlockText`	match	`PSAsyncShell`	`field:"ScriptBlockText" kind:match value:"PSAsyncShell"`

PSAsyncShell - Asynchronous TCP Reverse Shell

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`