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ThreatOther

Browser File System Access API lure — email walks you through granting a web page persistent read/write access to your Desktop / Documents / Downloads (2026 File-System-Access abuse)

browser-filesystem-access-api-lure

What this tier means

High-confidence threat indicator — phishing, impersonation, BEC, or scam pattern. Strong contributor to the trash decision.

How Gorganizer detects this

Email walks the recipient through granting a malicious web page persistent read/write access to a local folder via the Browser File System Access API (showDirectoryPicker, showOpenFilePicker, showSaveFilePicker). Chrome, Edge, and Opera ship this API by default in 2024+, gated only by a single browser consent prompt. Attackers phrase the lure as a "sync setup", "file transfer", or "bundle pickup" and walk the user through steps 1, 2, 3: click the link, click Allow, pick your Desktop / Documents / Downloads. Once granted, the attacker page holds the FileSystemHandle for that folder and can silently read and overwrite every file in it — SSH keys, browser cookies, shell rc files, sensitive docs. Fires when the body contains picker-prompt language (click Allow, grant folder access, select your folder, showDirectoryPicker) AND a local folder name (Desktop, Documents, Downloads, Pictures, Videos, home, root). Excludes known cloud-storage vendors (Google Drive, Dropbox, OneDrive, iCloud, Box, Backblaze, Sync.com, Tresorit, Nextcloud, Owncloud) who legitimately use this API for sync setup, and newsletters / replies where the pattern is discussion rather than instruction.

False-positive guard

Every signal in Gorganizer feeds a multi-module score — never a sole verdict. This is a threat-tier signal — it adds a strong contribution to the trash score. The full pipeline still requires convergence across multiple modules + a margin over the safety floor before deletion happens, and Gmail's trash (30-day recovery) is always used — never permanent delete.

About the scoring engine

Gorganizer's scoring engine emits over 1,800 signals across six modules — headers, sender, subject, body, attachments, and structural metadata. Every email is scored by every module independently; the final verdict requires multiple modules to agree and the trash score to beat the safety floor by a margin.

Sacred safety guards — never delete starred emails, replies, calendar invites, receipts/invoices, or attachments — apply unconditionally regardless of any signal.

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