{
  "family": "hiddeninstall",
  "sample_count": 2,
  "category": "advanced_threat",
  "description": "Adware:Win32/Hiddeninstall (also detected as PUP.Optional.HiddenInstall) is a generic classification for software deployment wrappers that silently install Potentially Unwanted Programs (PUPs), Adware, and sometimes full-fledged malware without displaying a user interface or explicitly asking for consent (`T1189`).<br><br><b>Understanding Hiddeninstall (Silent Droppers)</b><br>To an end-user, Hiddeninstall is entirely invisible; they may think they downloaded a portable application or that an installation failed, only to later discover unwanted toolbars, changed homepages, and system sluggishness. For a security analyst, these silent installers are a significant vector for enterprise compromise, bypassing user awareness training entirely.<br><br><b>Execution and Evasion Mechanics</b><br>Hiddeninstall wrappers are often distributed via peer-to-peer networks, cracked software sites, or deceptive 'Download Now' buttons on file-sharing portals. The executable is typically a compiled script (like AutoIt or Inno Setup) configured to run in 'silent' or 'very silent' mode. Upon execution, it extracts its payload into the `%Temp%` directory (`T1027.009`) and uses command-line arguments (e.g., `/S` or `/quiet`) to force the installation of bundled applications without rendering any GUI windows. It often modifies the Registry (`T1112`) to suppress standard Windows UAC prompts if the user has disabled default security settings.<br><br><b>Indicators of Compromise & Impact</b><br>The primary impact is the stealthy installation of nuisance or malicious software. Host-based IoCs include EDR alerts for known installer framework executables (like `setup.exe` or `install.exe`) launching with silent command-line switches (`/S`, `/SILENT`, `/VERYSILENT`) and immediately dropping multiple, unrelated executables into the Temp directory. Network IoCs include sudden spikes in HTTP traffic to known adware affiliate networks as the silent installer 'phones home' to register the successful installation.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1059.003",
    "T1027.009",
    "T1189"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise (Initial distribution via deceptive downloads)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1059.003",
      "name": "Command and Scripting Interpreter: Windows Command Shell (Using silent command line arguments for installation)",
      "tactic": "Execution"
    },
    {
      "id": "T1027.009",
      "name": "Obfuscated Files or Information: Embedded Payloads (Extracting the PUPs from the wrapper)",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Identify the source of the initial executable (e.g., a file downloaded via a web browser) and block the originating domain.",
    "Review the Windows Event Logs for recent application installations occurring concurrently with the execution of the suspicious file.",
    "Run an enterprise-grade anti-malware scan to clean up the adware and persistent registry hooks left behind by the silent installer.",
    "Implement Application Control (AppLocker) to strictly prevent the execution of untrusted binaries from the `%Temp%` directory."
  ],
  "what_to_avoid": [
    "Do not assume a user intentionally installed the adware; Hiddeninstall specifically bypasses user interaction.",
    "Avoid relying solely on 'Add/Remove Programs' for cleanup, as silently installed adware often omits uninstaller entries to maintain persistence."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}