Detection rules › Sigma
Base64 Encoded PowerShell Command Detected
Detects usage of the "FromBase64String" function in the commandline which is used to decode a base64 encoded string
Known false positives
- Administrative script libraries
MITRE ATT&CK coverage
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Sysmon | Event ID 1: Process creation |
| Security-Auditing | Event ID 4688: A new process has been created. |
Rule body
title: Base64 Encoded PowerShell Command Detected
id: e32d4572-9826-4738-b651-95fa63747e8a
status: test
description: Detects usage of the "FromBase64String" function in the commandline which is used to decode a base64 encoded string
references:
- https://gist.github.com/Neo23x0/6af876ee72b51676c82a2db8d2cd3639
author: Florian Roth (Nextron Systems)
date: 2020-01-29
modified: 2023-01-26
tags:
- attack.stealth
- attack.t1027
- attack.execution
- attack.t1140
- attack.t1059.001
logsource:
category: process_creation
product: windows
detection:
selection:
CommandLine|contains: '::FromBase64String('
condition: selection
falsepositives:
- Administrative script libraries
level: high
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
CommandLine|contains: '::FromBase64String('
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
CommandLine | match |
| field:"CommandLine" kind:match value:"::FromBase64String(" |