huntrule

Suspicious PowerShell In-Memory Execution with AES Decryption

PremiumReviewedSigma · High · v1
Product
windows
Category
ps_script
Author
HuntRule
Published
2026-10-21
Updated
2026-10-21
AnalysisDetection

ATT&CK techniques

Execution → Defense Evasion

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule detects PowerShell script blocks that combine Invoke-Expression with AES and base64 decryption routines. The DarkCloud stealer chain decrypts an obfuscated payload in memory and executes it via Invoke-Expression. Pairing in-memory execution with cryptographic decryption is characteristic of staged fileless loaders.

Reporting behind it

Related detections9 linkedT1027 — drag to rearrange
Suspicious Encoded PowerShell Command Execution
Suspicious PEAKLIGHT Memory-Only PowerShell Downloader Flags (via process_creation)
Obfuscated PowerShell Script: Indirect Cmdlet Execution via ExportedCommands Array Index
Suspicious PowerShell String Concatenation Obfuscation for Batch Extension via LNK (via process_creation)
Suspicious PowerShell Spawned from PyInstaller MEI Extraction Folder (via process_creation)
Suspicious PowerShell Encoded Command Execution
Suspicious PowerShell Invoke-Expression with Replace Obfuscation
Malicious Emmenhtal JavaScript Loader Spawning Encoded PowerShell
Suspicious Python Interpreter Launching Encoded PowerShell via subprocess
Suspicious PowerShell In-Memory Execution with AES Decryption
Pivot detection · T1027 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.