{
  "family": "pshell",
  "sample_count": 3,
  "category": "ransomware",
  "description": "Trojan:PowerShell/Pshell is not a specific malware family, but a highly critical **Generic Heuristic Detection** focused entirely on the malicious abuse of the Windows PowerShell framework. Microsoft Defender and other AV engines use this classification when they detect a PowerShell script or command-line execution exhibiting behaviors that strongly indicate malicious intent, regardless of the specific payload being delivered.<br><br><b>Understanding Pshell (Living off the Land)</b><br>To an end-user, this detection usually appears as a blocked script execution in the background. For a security analyst, Pshell is a massive red flag indicating an attack utilizing 'Living off the Land' (LotL) techniques. By abusing PowerShell (`T1059.001`), attackers leverage a trusted, built-in system administration tool to download payloads, execute code in memory, and bypass traditional application whitelisting and file-based antivirus scanners.<br><br><b>Execution and Evasion Mechanics</b><br>The specific mechanics triggering a Pshell alert are vast. Common triggers include: obfuscated or heavily encoded PowerShell scripts (e.g., using Base64 encoding via the `-enc` or `-EncodedCommand` flags) (`T1027`); scripts that attempt to use `Invoke-WebRequest` or `Net.WebClient` to download executables directly into memory (fileless malware) (`T1105`); scripts attempting to bypass the Execution Policy (`-ExecutionPolicy Bypass`); or scripts containing known malicious cmdlets like `Invoke-ReflectivePEInjection` (often associated with tools like Empire or PowerSploit).<br><br><b>Indicators of Compromise & Impact</b><br>The impact depends entirely on what the PowerShell script was attempting to execute (ranging from a simple coinminer to a devastating ransomware deployment). Host-based IoCs are centered around the PowerShell operational event logs (Event IDs 4104, 4103) which must be analyzed to decode the obfuscated command that triggered the AV block. Network IoCs include the PowerShell process (`powershell.exe`) making anomalous outbound connections to download secondary payloads.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1059.001",
    "T1105",
    "T1027"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1059.001",
      "name": "Command and Scripting Interpreter: PowerShell (The core heuristic trigger)",
      "tactic": "Execution"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information (Encoded commands)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (Downloading payloads via PS)",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Immediately review the Windows Event Logs (specifically PowerShell Operational logs, Event ID 4104 'Script Block Logging') to capture and decode the exact script that executed.",
    "Isolate the endpoint if the decoded script indicates a successful payload execution (e.g., it dropped a file or established a reverse shell) before the AV could block it.",
    "Analyze the decoded script to identify C2 domains or IP addresses and block them at the network perimeter.",
    "Ensure PowerShell Constrained Language Mode is enforced and Script Block Logging is enabled across the enterprise."
  ],
  "what_to_avoid": [
    "Do not ignore the alert assuming it is a benign admin script; heavily encoded or web-downloading PowerShell commands are rarely legitimate administrative tasks.",
    "Avoid relying solely on file-based AV logs; you must investigate the PowerShell command line arguments and script blocks to understand the attack."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}