Hunting For Startup Folder Persistence

Hunting for Startup Folder Persistence

Overview

Attackers use Windows startup folders for persistence (MITRE ATT&CK T1547.001 — Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder). Files placed in %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup execute automatically at user logon. This skill scans startup directories for suspicious files, monitors for real-time changes using Python watchdog, and analyzes file metadata to detect persistence implants.

When to Use

• When investigating security incidents that require hunting for startup folder persistence
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Detection Gaps & Validation

• Both folders, or you miss half: monitor per-user %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup AND all-users %ProgramData%\Microsoft\Windows\Start Menu\Programs\Startup. A watchdog on only one is a guaranteed blind spot.
• Extension filtering isn't enough: a .lnk whose target is encoded PowerShell or a UNC/HTTP path looks benign by extension — you must resolve and inspect the LNK target, not just flag .exe/.bat/.vbs/.ps1.
• Offline profiles: logged-off users' AppData isn't seen by a live agent — scan offline profiles too.
• SACL dependency: Windows EID 4663 only fires if object-access auditing (SACL) is set on the startup folders — off by default.
• Validate: run Atomic T1547.001 startup-folder drop; confirm a new-file event AND successful LNK target extraction.
• FP tuning: baseline vendor shortcuts (Teams, Steam, OEM utilities) by signer + resolved target path.

Prerequisites

• Python 3.9+ with watchdog, pefile (optional for PE analysis)
• Access to Windows startup folders (user and all-users)
• Windows Event Logs for Event ID 4663 correlation (optional)

Steps

1. Enumerate all files in user and system startup directories
2. Analyze file types, creation timestamps, and digital signatures
3. Flag suspicious file extensions (.bat, .vbs, .ps1, .lnk, .exe)
4. Check for recently created files (< 7 days) as potential implants
5. Monitor startup folders in real-time using watchdog FileSystemEventHandler
6. Correlate with known legitimate startup entries
7. Generate threat hunting report with T1547.001 MITRE mapping

Expected Output

• JSON report listing all startup folder contents with risk scores, file metadata, and suspicious indicators
• Real-time monitoring alerts for new file creation in startup directories