DEV Community

Darkssel
Darkssel

Posted on

How to Check If Someone Has Been Accessing Your Windows PC Without Your Permission

#windows #security #privacy #monitoring

You leave your PC for a few minutes.

When you come back, the mouse is in a different position.

A file you didn't open is now on your desktop.

Your paranoia kicks in:

Has someone been snooping around my PC?

It's a valid concern.

Physical access, remote access, USB devices — there are many ways someone could access your system without your knowledge.

The good news?

Windows records many types of login, system, and security activity — you just need to know where to look.

This guide shows you how to check if someone has been accessing your Windows PC — from physical access to remote connections — so you can know for sure.

7 Ways to Check for Unauthorized Access

1. Check Task Manager for Remote Control Programs

Remote access programs are the most common tool for unauthorized access.

What to look for:

  • TeamViewer
  • AnyDesk
  • RemotePC
  • Chrome Remote Desktop
  • UltraViewer
  • LogMeIn
  • Ammyy Admin
  • Splashtop
  • Zoho Assist

How to check:

  1. Open Task Manager (Ctrl + Shift + Esc)
  2. Go to the Processes tab
  3. Look for any of the above names
  4. Also check the Startup tab for these programs

If you find any:

  • Check if they're running without your permission
  • Open the app and see if there's an active session
  • Uninstall them if you don't use them

Pro tip: Some malware uses the same names but is located in different folders. Check the file location by right-clicking in Task Manager → Open file location.

2. Check Remote Desktop Settings

Windows has built-in Remote Desktop Protocol (RDP). If enabled, someone could connect to your PC remotely.

How to check:

  1. Press Win + I to open Settings
  2. Go to System → Remote Desktop
  3. Check if Remote Desktop is On

What to do:

  • If it's On and you don't use it, turn it Off
  • If you need it, check who has access

Advanced check:

  1. Press Win + R, type cmd, press Enter
  2. Run: query user
  3. If you see rdp-tcp# followed by a number, someone is connected via Remote Desktop

3. Check Network Connections for Suspicious Activity

Every remote connection uses your network. You can see all active connections using a simple command.

How to check:

  1. Open Command Prompt as Administrator
  2. Run: netstat -ano | findstr "ESTABLISHED"
  3. Look for unfamiliar IP addresses or ports

Common remote access ports to be aware of:

Port Common Use
3389 Remote Desktop Protocol (RDP)
5900 Common VNC port
80 / 443 Normal web traffic — not proof of remote access on its own

If you see suspicious connections:

  1. Note the IP address
  2. Run: netstat -ano | findstr "ESTABLISHED" to see the PID (Process ID)
  3. Open Task Manager → Details tab → match the PID to a process name

4. Check Windows Event Viewer for Login Logs

Windows logs every login attempt — successful and failed.

How to check:

  1. Press Win + R, type eventvwr.msc, press Enter
  2. Go to Windows Logs → Security

Look for these Event IDs:

Event ID What It Means
4624 Successful logon
4625 Failed logon
4648 Logon with explicit credentials
4672 Special privileges assigned (administrator logon)

Filter for remote logons:

  1. Click Filter Current Log (right panel)
  2. Enter Event ID 4624 in the filter box
  3. Click OK

Important: Look for logons with:

  • Logon Type 10 — RemoteInteractive (RDP)
  • Logon Type 3 — Network (network share)
  • Unusual times (e.g., 3 AM on a weekend)

Pro tip: If you see many 4624 events from unknown sources at odd hours, you may have a problem.

5. Check USB History

Someone could have plugged in a USB drive and copied your files in seconds.

How to check USB history:

  1. Press Win + R, type regedit, press Enter
  2. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USBSTOR
  3. Look for devices you don't recognize and check their timestamps

Alternative method using PowerShell:

  1. Open PowerShell as Administrator
  2. Run: 
Get-ChildItem -Path "HKLM:\SYSTEM\CurrentControlSet\Enum\USBSTOR" -Recurse |
    ForEach-Object { Get-ItemProperty $_.PSPath } |
    Select-Object FriendlyName, LastWriteTime
Enter fullscreen mode Exit fullscreen mode

What to look for: USB connections at unusual hours or devices you don't recognize.

6. Check Recently Installed Programs

If someone accessed your PC, they might have installed software — either legitimate remote tools or malware.

How to check:

  1. Open Settings → Apps → Installed apps
  2. Sort by Install date (newest first)
  3. Look for anything you don't recognize

Also check:

  • Web browser extensions (Chrome, Edge, Firefox)
  • Scheduled tasks (Task Scheduler)
  • Startup folder (shell:startup)

7. Check Windows Defender Logs

Attackers often disable Windows Defender before deploying malware. If Defender was turned off while you were away, that's a red flag.

How to check:

  1. Open Event Viewer (eventvwr.msc)
  2. Go to Windows Logs → System
  3. Filter by Event Source: Microsoft-Windows-Windows Defender
  4. Look for events indicating real-time protection was turned off

Note: If Defender is off and you didn't turn it off yourself, investigate immediately.

Red Flags: Signs Someone Has Been Accessing Your PC

Red Flag What It Means
Mouse moves or clicks on its own Remote session or malware
Programs open and close unexpectedly Remote activity
New user accounts you don't recognize Someone created a backdoor
Files or folders have been renamed or moved Physical or remote access
Security software is disabled Attacker turned it off
Unusual network activity Data exfiltration or remote connection
Computer wakes up by itself Someone triggered a wake event
USB connection at unusual hours Physical access

What If You Want to Monitor Unauthorized Access Automatically?

Manually checking Task Manager, Event Viewer, Registry, and network connections is time-consuming.

You have to:

  • Check Task Manager every time you're suspicious
  • Review Event Viewer logs
  • Scan USB history
  • Monitor network connections

That's exactly why I built SysPulse — a lightweight Windows security monitor that automatically monitors important system activity and sends you Telegram alerts when monitored events occur.

SysPulse can:

  • Detect new processes and show their full file paths
  • Monitor CPU and RAM anomalies
  • Detect USB connections in real-time
  • Detect startup changes
  • Send Telegram alerts for monitored events
  • Use less than 30MB of RAM

You can set it up once and let it watch your PC for you — so you don't have to check manually every time you feel suspicious.

You can find it at: syspulse.pro

Summary Table

Check What to Look For How to Do It
Remote programs TeamViewer, AnyDesk, etc. Task Manager
Remote Desktop RDP enabled Settings → Remote Desktop
Network connections Suspicious IPs/ports netstat -ano
Event Viewer 4624, 4625, 4648, 4672 Event Viewer → Security
USB history Unknown devices Registry → USBSTOR
Installed programs Unknown software Settings → Installed apps
Defender logs Protection turned off Event Viewer

Final Thought

If you're worried about someone accessing your PC, don't ignore that feeling.

Start with the simple checks:

  1. Check Task Manager for remote programs
  2. Review Event Viewer for unknown logins
  3. Check USB history for unknown devices

If you want peace of mind without checking manually every day, a real-time monitoring tool like SysPulse can watch your system for you and alert you the moment something changes.

The key: Don't wait until something goes wrong. Know what's happening on your PC right now.

Have questions about checking for unauthorized access? Drop a comment below — I read every one.

Stay secure!

Top comments (0)