Base64 Encoded PowerShell Command Detected

Severity: high
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects usage of the "FromBase64String" function in the commandline which is used to decode a base64 encoded string

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell
Defense Evasion	`T1027` Obfuscated Files or Information, `T1140` Deobfuscate/Decode Files or Information

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `selection`

CommandLine|contains: '::FromBase64String('

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.