Openinstall

Overview

OpenInstall (classified across security vendors as Adware:Win32/OpenInstall and PUA:Win32/OpenInstall) is an aggressive software bundler and adware delivery platform. Distributed via misleading online download portals and cracked software repositories, OpenInstall wraps legitimate software installers with multiple unwanted payloads, including browser hijackers, system trackers, and background ad injection modules. It secretly changes default search engines and new tab pages across installed web browsers, establishes persistence through Windows scheduled tasks and Run registry entries, and intercepts user browsing traffic to display affiliate banners and redirect URLs.

Known aliases

Threat reports may refer to this family under multiple names:

• Adware:Win32/OpenInstall
• PUA:Win32/OpenInstall
• OpenInstall Bundler
• Program:Win32/OpenInstall
• Win32/OpenInstall

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1059.004: Restrict execution of scripting languages such as PowerShell, VBScript, or Python to authorized administrators. Enforce Script Block Logging.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_OPENINSTALL_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Openinstall"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "openinstall" ascii wide nocase
        $s2 = "adware:win32/openinstall" ascii wide nocase
        $s3 = "pua:win32/openinstall" ascii wide nocase
        $s4 = "openinstall bundler" ascii wide nocase
        $s5 = "program:win32/openinstall" ascii wide nocase
        $s6 = "win32/openinstall" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Openinstall (Adware) Execution & Triage
id: f9075799-203f-5545-ac2c-6daf04e55d4d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Openinstall malware family. Detects suspicious execution from temporary
  user directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/openinstall
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.adware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1176
- attack.t1547_001
- attack.t1053_005
- attack.t1112
- attack.t1071_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_OPENINSTALL_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Openinstall tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "openinstall" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Use the Windows Control Panel to systematically identify and uninstall all recently added programs, focusing on toolbars and 'search protectors'.
2. Deploy an enterprise adware removal tool (e.g., AdwCleaner) to strip the deeply embedded Scheduled Tasks and registry hooks left behind by the Openinstall framework.
3. Force a complete reset of all installed web browsers (Chrome, Edge, Firefox) to factory defaults to eradicate rogue extensions and restore the homepage.
4. Quarantine the original installer file to prevent further execution.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not rely solely on manual uninstallation via the Control Panel; Openinstall payloads frequently use watchdog services to immediately reinstall themselves.
2. Avoid ignoring the infection; adware tracking data is highly detailed and may expose corporate activities or provide a foothold for more severe malvertising attacks.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Adware:Win32/OpenInstall
• Trend Micro Security Research - PUA.Win32.OpenInstall Analysis
• MITRE ATT&CK - Browser Extensions (T1176)
• Search "openinstall" on VirusTotal (External Analysis)
• Search "openinstall" on Any.Run (Sandbox Sandbox)
• Search "openinstall" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Adware)

Explore other documented threats in the same operational category:

• Opensupdater
• Zdengo
• Bundlore
• Trymedia
• Ibryte
• Csdimonetize
• Tuscas
• Noon

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/openinstall.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.