{
  "family": "powstage",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nPowStage (or PowerShell Stager) refers to a class of fileless malware components used extensively in modern, \"Living off the Land\" (LotL) cyberattacks. A stager is a small, initial piece of code whose sole purpose is to establish a connection to a remote Command and Control (C2) server, download a much larger and more complex secondary payload (like a Cobalt Strike beacon, ransomware, or RAT), and execute it directly in the system's memory without touching the hard drive.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nPowStage is typically delivered via weaponized Microsoft Office documents containing malicious macros, disguised shortcut (`.lnk`) files in phishing emails, or via exploitation of web application vulnerabilities.\n\nOnce the initial vector is triggered, the PowerShell Stager executes:\n<ul>\n<li><strong>Fileless Execution:</strong> The stager invokes the legitimate Windows PowerShell interpreter (`powershell.exe`) but passes the malicious script directly via the command line (e.g., using `-EncodedCommand` and Base64 encoding). This avoids writing a `.ps1` script file to disk, evading many traditional antivirus scanners.</li>\n<li><strong>AMSI Bypass:</strong> Advanced PowStage variants include code specifically designed to hook and bypass the Windows Anti-Malware Scan Interface (AMSI), blinding Windows Defender and other modern AV tools to the script's contents.</li>\n<li><strong>Payload Fetch and Inject:</strong> The stager utilizes commands like `Invoke-WebRequest` or `Net.WebClient` to download the secondary payload (often encrypted or disguised as an image file). It then uses reflective DLL injection to load this payload directly into the memory space of a legitimate process.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nThe execution of a PowStage script is a critical security incident indicating the first successful stage of a major compromise. Because the stager successfully bypassed perimeter defenses and executed code, the endpoint is actively communicating with adversary infrastructure and is likely seconds away from receiving a devastating secondary payload.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Behavioral Analysis (EDR):</strong> Detection relies almost entirely on Endpoint Detection and Response (EDR) solutions monitoring for suspicious PowerShell behavior, such as `powershell.exe` making unexpected outbound network connections or attempting to inject code into other processes.</li>\n<li><strong>Immediate Isolation:</strong> The endpoint must be isolated immediately to sever the connection to the C2 server before the secondary payload finishes downloading and executing.</li>\n<li><strong>Forensic Investigation:</strong> Analyze PowerShell transaction logs (Script Block Logging - Event ID 4104) to determine exactly what the stager downloaded, where it came from, and which process it injected into.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.PowStage",
    "PowerShell.Stager",
    "Trojan.Downloader.PowerShell"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1059.001",
    "T1055.001",
    "T1562.001",
    "T1105"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-02T07:16:31Z",
  "type": "Trojan / Dropper (Fileless)",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}