Fullscreen
Table of Contents
Overview
Adware:Win32/Fullscreen is an aggressive, highly disruptive Potentially Unwanted Program (PUA) and adware family designed to monetize an infected endpoint by forcefully injecting massive, full-screen advertisements into the user's web browser or directly onto the Windows desktop, regardless of what the user is doing.
Understanding Fullscreen Adware
To an end-user, a Fullscreen infection renders the computer nearly unusable. The adware completely hijacks the screen real estate, constantly interrupting workflows with unavoidable, full-screen pop-ups that are often difficult to close. For a security analyst, this represents a severe degradation of endpoint functionality and a significant risk of secondary infections, as these aggressive ads frequently employ malvertising to deploy actual trojans or ransomware.
Execution and Disruption Mechanics
Fullscreen is typically distributed via deceptive software bundlers (`T1189`) found on torrent sites or third-party freeware portals. Upon execution (`T1204.002`), it establishes deep persistence, often creating multiple randomized Scheduled Tasks (`T1053.005`) and Registry Run keys to ensure it survives reboots. It utilizes hidden browser extensions (`T1176`) or standalone adware processes to intercept web traffic and inject its payload. It deliberately uses Windows UI APIs (`T1562`) to force the advertisement windows to stay 'always on top' and maximize to full screen, maximizing the chance the user accidentally clicks the ad and generates affiliate revenue.
Indicators of Compromise & Impact
The primary impact is the total loss of user productivity and the high risk of secondary malvertising infections. Incident responders will observe anomalous HTTP/HTTPS traffic routing through known, aggressive adware affiliate networks. EDR logs will flag the installation of the rogue Scheduled Tasks and the constant launching of hidden browser instances or unknown executables attempting to draw full-screen UI elements.
MITRE ATT&CK Techniques
Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1189 | Drive-by Compromise (Bundled Installers) | Initial Access | ATT&CK ↗ |
T1053.005 | Scheduled Task/Job: Scheduled Task (Persistence for pop-ups) | Persistence | ATT&CK ↗ |
T1176 | Browser Extensions | Persistence | ATT&CK ↗ |
T1204.002 | User Execution: Malicious File | Execution | ATT&CK ↗ |
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-STM | Scheduled Task Creation Analysis | Detect | T1053.005 | Audit task creation targeting system and hidden service directories; verify task author credentials. |
D3-BEA | Browser Extension Allowlisting | Harden | T1176 | Deploy enterprise browser policies via GPO or Intune to block unauthorized side-loaded extensions and add-ons. |
D3-RBI | Remote Browser Isolation | Isolate | T1189 | Execute untrusted web browsing sessions in disposable cloud containers to isolate drive-by exploits from local endpoints. |
D3-FEA | File Execution Analysis | Harden | T1204.002 | Enforce AppLocker and Windows Defender Application Control (WDAC) to block executable launches from temporary and user-writable directories. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_FULLSCREEN_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Fullscreen"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "fullscreen" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Fullscreen (Ransomware) Execution & Triage
id: 384ce563-de15-5f87-833e-76f9b6fe55d2
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Fullscreen malware family. Detects volume shadow copy deletion, boot status
tampering, and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/fullscreen
- 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.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1053_005
- attack.t1189
- attack.t1204_002
- attack.t1176
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \vssadmin.exe
- \wmic.exe
- \wbadmin.exe
- \bcdedit.exe
CommandLine|contains:
- delete shadows
- shadowcopy delete
- resize shadowstorage
- recoveryenabled no
- ignoreallfailures
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: criticalTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_FULLSCREEN_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Fullscreen 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 = "fullscreen" 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.
- Use the Windows Control Panel to attempt uninstallation of the adware and any bundled software installed on the exact same date.
- Deploy an enterprise adware removal tool (e.g., AdwCleaner or Malwarebytes) to locate and strip the deeply embedded Scheduled Tasks and hidden registry hooks.
- Force a complete reset of all installed web browsers to factory defaults to eradicate rogue extensions.
- If the full-screen ads prevent interaction with the desktop, reboot the computer into Safe Mode to perform the cleanup.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not instruct the user to simply 'click the X' on the ads; aggressive adware often fakes the close button to register an illicit click or trigger a secondary download.
- Avoid ignoring the infection; the malvertising networks utilized by Fullscreen often rotate their payloads and may drop severe malware.
References & External Analysis
- Search "fullscreen" on VirusTotal (External Analysis)
- Search "fullscreen" on Any.Run (Sandbox Sandbox)
- Search "fullscreen" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Fullscreen and what threat category does it belong to?
Fullscreen is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Fullscreen establish persistence and evade defensive controls?
Fullscreen typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Fullscreen compromise?
Security teams responding to Fullscreen should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What cryptographic algorithms and file targeting techniques does Fullscreen employ during execution?
Fullscreen typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options.
Are decryptors available for Fullscreen, and what is the recommended recovery procedure?
Decryption availability for Fullscreen depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups.
How do I remove Fullscreen from Windows?
Manual removal of Fullscreen is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
What are the main symptoms of a Fullscreen infection?
Symptoms of Fullscreen can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Ransomwares
Want to prevent Fullscreen and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Containment & Incident Response.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/fullscreen.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.