Keylogger:MSIL/KeyloggerDH is a keylogging trojan written in Microsoft Intermediate Language (MSIL), the bytecode used by .NET Framework applications. This malware silently records every keystroke you make on your infected Windows machine, capturing passwords, credit card numbers, private messages, and anything else you type. It typically arrives bundled with pirated software, fake updates, or disguised as legitimate utilities, and once installed, it operates invisibly in the background while stealing your most sensitive information.
Unlike ransomware that announces itself immediately, KeyloggerDH works in silence. You might not know you're infected until fraudulent charges appear on your bank statement or your online accounts get hijacked. The MSIL implementation makes it relatively easy to detect with updated antivirus software, but many infections persist because users don't realize they need to scan their systems.
Threat Profile
| Attribute | Details |
|---|---|
| Threat Family | Keylogger trojan (information stealer) |
| Detection Names | Keylogger:MSIL/KeyloggerDH, MSIL/Keylogger.DH, Trojan.MSIL.Keylogger, KeyLogger.MSIL.Gen |
| Platform | Windows (requires .NET Framework 2.0 or higher) |
| First Documented | Mid-to-late 2010s (exact discovery date varies by variant) |
| Primary Distribution | Software bundling, fake installers, malicious email attachments, exploit kits |
| Persistence Mechanism | Registry Run keys, Startup folder entries, scheduled tasks |
| Core Capabilities | Keystroke logging, clipboard capture, screenshot capture (some variants), data exfiltration via HTTP/SMTP |
| Typical File Locations | %APPDATA%, %LOCALAPPDATA%, %TEMP% subfolders with random GUIDs or common-sounding names |
| Network Behavior | Periodic HTTP POST requests or SMTP connections to attacker-controlled servers; may use DNS tunneling |
| Common IoCs | Log files in local directories (often .txt or .dat), suspicious outbound connections on non-standard ports |
| Removal Difficulty | Moderate—persistence mechanisms must be eliminated and all artifacts cleaned |
| Reinfection Risk | High if the original infection vector (pirated software, compromised installer) remains on the system |
How It Spreads
Keylogger:MSIL/KeyloggerDH doesn't spread like a worm—it arrives on your system through deliberate distribution by cybercriminals. The most common entry point is software bundling, where the keylogger is packaged inside installers for free utilities, game cheats, video converters, or productivity tools downloaded from shady websites. These bundlers often use confusing installation wizards that bury the keylogger installation behind "Custom" settings or pre-checked boxes that users skip past.
Another frequent vector is fake update notifications. You might see a browser pop-up claiming your Flash Player, Java, or media codec is out of date. Clicking "Update Now" downloads an installer that looks legitimate but actually contains the keylogger payload. Email attachments are also used—typically disguised as invoices, shipping notifications, or tax documents. The attached file might be a .ZIP archive containing an executable, or a malicious Office document with macros that download the keylogger when enabled.
Distribution methods include:
- Pirated software bundles — Cracked applications from torrent sites or file-sharing platforms with the keylogger embedded in the installer or crack file
- Fake download buttons — Misleading advertisements on freeware sites that look like legitimate download links but serve malware instead
- Malvertising campaigns — Compromised ad networks that redirect users to exploit kit landing pages that attempt drive-by downloads
- Phishing emails — Messages impersonating businesses, government agencies, or known contacts with infected attachments
- Trojanized utilities — Legitimate-looking system optimization tools, browser extensions, or screen savers that contain the keylogger as a hidden component
- USB drives and removable media — Less common but still viable; infected autorun files that execute when the drive is connected
What It Does On Your Machine
Once Keylogger:MSIL/KeyloggerDH executes on your system, it immediately establishes persistence so it survives reboots. The malware typically copies itself to a subdirectory in your user profile—often with a randomly-generated GUID folder name or something that sounds system-related like "SystemUpdate" or "WindowsDefender32". It then creates registry entries in the Run or RunOnce keys, or drops a shortcut in your Startup folder. Some variants create scheduled tasks that launch the keylogger at specific intervals or system events.
The keylogger's primary function is capturing every keystroke you make. It hooks into the Windows keyboard input system at a low level, intercepting keystrokes before they reach your applications. This means it captures everything—passwords typed into browsers, credit card numbers entered on shopping sites, private messages in chat applications, even text you delete before sending. The malware stores this captured data in log files, usually in the same directory where the executable resides, or in a hidden folder elsewhere in your user profile.
Many variants of KeyloggerDH also monitor your clipboard, capturing anything you copy and paste. This is particularly dangerous because many people use password managers that copy passwords to the clipboard when you auto-fill forms. The keylogger captures that clipboard content before you paste it, defeating the primary security advantage of password managers. Some versions also take periodic screenshots to capture on-screen keyboards, virtual keyboards, or form-filled data that wasn't actually typed.
The captured data gets transmitted to the attacker's command-and-control server, usually in batches to avoid generating obvious network traffic. The keylogger might send data via HTTP POST requests to a compromised legitimate website, SMTP emails to throw-away email accounts, or even DNS queries encoded with stolen information. Some variants encrypt the data before transmission, while others send it in plain text. The transmission schedule varies—some variants exfiltrate data every few minutes, others wait until a certain amount is collected or a specific time window occurs.
Manual Removal — Step by Step
Disconnect from the Internet
Before doing anything else, disconnect your computer from all networks. Unplug your Ethernet cable and turn off Wi-Fi. This prevents the keylogger from transmitting any additional captured data and stops the attacker from issuing new commands to the malware. Keep your machine offline throughout the entire removal process.
Boot into Safe Mode with Networking
Restart your computer and enter Safe Mode. On Windows 10/11, hold Shift while clicking Restart, then navigate to Troubleshoot > Advanced Options > Startup Settings > Restart, and press F5 for Safe Mode with Networking. Safe Mode loads only essential drivers and services, preventing most malware including KeyloggerDH from automatically starting. The "with Networking" option lets you download removal tools if needed.
Show Hidden Files and Folders
Open File Explorer, click View, then Options. In the View tab, select "Show hidden files, folders, and drives" and uncheck "Hide protected operating system files." Click OK. This makes the keylogger's hidden files visible so you can locate and delete them. Many variants hide themselves using the Windows "hidden" and "system" file attributes.
Identify and Terminate the Keylogger Process
Open Task Manager (Ctrl+Shift+Esc) and look for suspicious processes. KeyloggerDH often disguises itself with names like "svchost.exe," "csrss.exe," or "explorer.exe"—names that match legitimate Windows processes. The giveaway is the location: right-click the process, select "Open file location," and if it opens anywhere other than C:\Windows\System32, it's likely malicious. Right-click the suspicious process and select "End Task." Note the full file path for the next step.
Delete Persistence Mechanisms
Open Registry Editor (Win+R, type "regedit," press Enter) and navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and RunOnce. Look for entries with suspicious names or paths matching the keylogger location you identified. Delete those entries. Also check your Startup folder at C:\Users\[YourUsername]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup for any unfamiliar shortcuts. Open Task Scheduler (Win+R, type "taskschd.msc") and examine the task list for anything unfamiliar or matching the keylogger's naming pattern.
Delete the Malware Files
Navigate to the folder you identified in step 4 and delete the entire directory. Common locations include subfolders in %APPDATA% (C:\Users\[Username]\AppData\Roaming), %LOCALAPPDATA%, or %TEMP%. Delete any GUID-named folders or suspiciously named directories. Empty your Recycle Bin immediately afterward to prevent accidental restoration. If Windows says the file is in use, the process termination in step 4 may not have worked—reboot to Safe Mode again and try deletion before any services start.
Scan with Malwarebytes
You can temporarily reconnect to download Malwarebytes Free (malwarebytes.com) if you don't already have it, then disconnect again. Run a full Threat Scan. Malwarebytes has excellent detection for MSIL-based keyloggers and will catch any remnants or additional payloads you may have missed. Quarantine everything it finds. Consider running a second scan with Windows Defender or another reputable scanner as a verification step—different engines catch different variants.
Check Browser Extensions and Reset Settings
Some keylogger packages include browser components. Open each browser you use (Chrome, Edge, Firefox) and review installed extensions. Remove anything unfamiliar or anything installed around the time you suspect infection occurred. In Chrome, go to Settings > Reset Settings > Restore settings to their original defaults. Do the same for other browsers. This removes malicious search engine changes and homepage redirects that sometimes accompany keyloggers.
Change All Passwords
Assume every password you've typed since infection was captured. Once you're confident the keylogger is fully removed, reconnect to the internet and systematically change passwords for every important account—email, banking, shopping sites, social media, work systems. Do this from the cleaned computer or, better yet, from a different device you know is clean. Enable two-factor authentication wherever possible to protect against future credential theft.
Reboot and Verify
Restart your computer normally (not in Safe Mode) and monitor behavior carefully. Check Task Manager for the suspicious process again. Verify that your registry Run keys stayed clean. Monitor your outbound network connections using Windows Resource Monitor (search for "resmon" in Start) for any unexpected HTTP or SMTP traffic. If everything looks clean after 24 hours of normal use, you've likely succeeded. If suspicious behavior returns, the infection may have additional components requiring professional removal.
Prevention
- Download software only from official sources. Avoid torrent sites, file-sharing platforms, and third-party download repositories. Get applications directly from the publisher's website or the Microsoft Store. The convenience of "free" pirated software isn't worth the risk of keylogger infection.
- Keep Windows and .NET Framework updated. Enable automatic updates in Windows Update settings. While KeyloggerDH doesn't typically exploit vulnerabilities to install itself, keeping your system patched closes the door on other malware that might download keyloggers as secondary payloads.
- Use reputable antivirus with real-time protection. Windows Defender is adequate for most users if kept updated, but dedicated solutions like Malwarebytes Premium, Bitdefender, or Kaspersky offer additional layers of protection. Ensure real-time scanning is enabled so threats get blocked before execution.
- Be skeptical of email attachments and links. Never open attachments from unknown senders. Even if an email appears to come from someone you know, verify through a separate channel before opening unexpected attachments. Hover over links to see the actual destination before clicking.
- Read installation prompts carefully. When installing free software, always choose "Custom" or "Advanced" installation and read every screen. Uncheck any bundled offers, toolbars, or "recommended" additional software. If an installer won't let you opt out of extras, cancel the installation entirely.
- Use a password manager. While KeyloggerDH can capture clipboard content, a good password manager still dramatically reduces your keystroke exposure. You'll type far fewer passwords, limiting what a keylogger can capture. Choose one with auto-type features that minimize clipboard use.
- Monitor your accounts for suspicious activity. Regularly check bank statements, credit reports, and login histories on important accounts. Early detection of credential theft can limit the damage. Set up email or text alerts for account activity where available.
- Maintain offline backups of critical data. While keyloggers don't typically encrypt or delete files like ransomware does, infections often require complete system reinstallation to ensure cleanliness. Having good backups on an external drive that's not always connected prevents data loss during recovery.
Bring It In
Keylogger removal requires thoroughness. A single missed registry key, a leftover scheduled task, or a hidden backup copy of the malware means the infection persists and continues stealing your information. If you're uncomfortable with manual removal, uncertain whether you've gotten everything, or simply want the peace of mind that comes with professional verification, bring your computer to our Roswell shop.
We'll perform a complete forensic cleaning—not just running a scanner, but manually hunting down persistence mechanisms, checking network configurations, verifying system file integrity, and testing to ensure the infection is truly gone. We'll also help you assess what data may have been compromised and provide concrete guidance on securing your accounts. Call us at (770) 741-0799 or stop by—we're located right here in Roswell, and we'll have you back up and running securely, usually same-day.