CowboyStealer is an information-stealing trojan that targets credentials, cryptocurrency wallets, browser data, and sensitive files stored on Windows systems. First observed in late 2023, this malware is typically distributed through phishing emails, cracked software bundles, and malicious advertisements disguised as legitimate software downloads. Once installed, it silently harvests login credentials from browsers, FTP clients, email applications, and crypto wallet software before exfiltrating the stolen data to remote command-and-control servers.
Unlike ransomware that immediately announces its presence, CowboyStealer operates covertly in the background, making detection difficult until victims notice unauthorized account access or financial losses. The malware employs anti-analysis techniques to evade security software and can download additional payloads, potentially leading to secondary infections including remote access trojans or cryptocurrency miners.
Threat Profile
| Attribute | Details |
|---|---|
| Malware Family | Information Stealer / Credential Harvester |
| Also Known As | Cowboy Stealer, Win32/CowboyStealer |
| Target Platform | Windows 7 through Windows 11 (32-bit and 64-bit) |
| First Documented | Late 2023 |
| Distribution Methods | Phishing emails, software cracks, malvertising, bundled installers |
| Persistence Mechanisms | Registry Run keys, scheduled tasks, startup folder entries |
| Primary Capabilities | Browser credential theft, cryptocurrency wallet extraction, FTP client harvesting, email credential theft, file exfiltration, screenshot capture |
| Targeted Applications | Chrome, Firefox, Edge, Brave, Opera; FileZilla, WinSCP; Outlook, Thunderbird; Exodus, Electrum, Atomic Wallet, MetaMask |
| Network Behavior | HTTP/HTTPS POST requests to C2 servers; data typically exfiltrated as compressed archives |
| Common Artifacts | Executable in %APPDATA% or %LOCALAPPDATA% with randomized names; stolen data staged in temporary folders before transmission |
| Anti-Analysis Features | Virtual machine detection, sandbox evasion, debugger checks (typical for this family) |
| Removal Difficulty | Moderate—requires thorough credential rotation after removal |
How It Spreads
CowboyStealer primarily reaches victims through social engineering tactics that exploit trust and urgency. The most common infection vector involves phishing emails that impersonate shipping notifications, invoice reminders, or security alerts from well-known companies. These emails contain malicious attachments—often disguised as PDF files or Word documents with macros—that download and execute the stealer when opened. The attackers frequently spoof sender addresses to appear legitimate, making these emails particularly deceptive.
Software piracy represents another major distribution channel. Users searching for cracked versions of expensive software, game cheats, or license key generators frequently download trojanized installers from file-sharing sites and torrent platforms. These packages bundle CowboyStealer with the promised software, and the malware activates during what appears to be a normal installation process. The infection happens before users even realize the "cracked" software doesn't work as advertised.
Malicious advertising campaigns—known as malvertising—have also been used to spread this threat. Fake download buttons on software repositories, compromised ad networks serving infected payloads, and search engine ads leading to lookalike websites all serve as infection points. Common distribution methods include:
- Phishing email attachments with macro-enabled documents or compressed executables
- Cracked software bundles downloaded from warez sites and peer-to-peer networks
- Fake software updates for browsers, media players, or system utilities
- Malicious browser extensions initially appearing legitimate but later updated with stealer functionality
- Infected USB drives left in public spaces or received through mail campaigns targeting specific organizations
- Compromised legitimate websites serving drive-by downloads through exploit kits
- Discord and Telegram bots offering "free" game items, cryptocurrency, or software licenses
What It Does On Your Machine
Once executed, CowboyStealer immediately begins reconnaissance to determine whether it's running in a real user environment or a security researcher's analysis system. If it detects virtual machines, sandboxes, or debugging tools, it may terminate itself to avoid analysis. On a genuine user system, the malware establishes persistence by creating registry entries or scheduled tasks that ensure it runs automatically at system startup. This allows the stealer to continue operating even after reboots.
The core functionality revolves around systematic credential harvesting. CowboyStealer targets browser profile directories where passwords, cookies, autofill data, and browsing history are stored. It can extract saved credentials from Chromium-based browsers (Chrome, Edge, Brave, Opera) and Firefox, even when those credentials are stored in encrypted databases. The malware also searches for cryptocurrency wallet files, which often contain the private keys needed to access and transfer digital assets. Desktop wallet applications like Exodus, Electrum, and Atomic Wallet are specifically targeted, along with browser extension wallets such as MetaMask.
Beyond browsers and wallets, the stealer harvests credentials from FTP clients (FileZilla, WinSCP), email applications (Outlook, Thunderbird), messaging platforms (Discord, Telegram tokens), and VPN software. It may also take screenshots to capture additional information displayed on screen, and some variants search the file system for documents containing keywords like "password," "wallet," "seed," or "private key." All stolen data is compressed into an archive and transmitted to attacker-controlled servers, often using legitimate cloud storage services or compromised web hosts as intermediary collection points.
The file system artifacts typically look like this:
Manual Removal — Step by Step
Disconnect From All Networks Immediately
Before doing anything else, disconnect your computer from the internet by unplugging the ethernet cable or turning off Wi-Fi. This prevents the malware from transmitting any additional stolen data and stops it from receiving commands or downloading secondary payloads. Physical disconnection is more reliable than software-based network disabling.
Boot Into Safe Mode With Networking
Restart your computer and enter Safe Mode, which loads only essential system processes and prevents most malware from running automatically. On Windows 10/11, hold Shift while clicking Restart, then navigate to Troubleshoot > Advanced Options > Startup Settings > Restart, and select option 5 (Safe Mode with Networking). You'll need networking enabled to download removal tools in later steps.
Open Task Manager and Terminate Suspicious Processes
Press Ctrl+Shift+Esc to open Task Manager. Look for processes with random names running from AppData folders, processes consuming unusual network bandwidth, or unfamiliar executables. Right-click suspicious processes, select "Open file location," note the path, then end the process. CowboyStealer often disguises itself with names similar to legitimate Windows services like "svhost.exe" (note the missing 'c') or generic names like "system32.exe" running from user directories.
Remove Persistence Mechanisms
Open Registry Editor (type regedit in the Start menu) and navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run. Look for unfamiliar entries pointing to executables in AppData or Temp folders and delete them. Next, open Task Scheduler (taskschd.msc), review the Task Scheduler Library, and delete any tasks that run suspicious executables or have vague names like "System Update Service."
Delete the Malware Files and Folders
Navigate to the file locations you identified in step 3. Common locations include C:\Users\[YourName]\AppData\Local and C:\Users\[YourName]\AppData\Roaming. Delete the entire folder containing the malicious executable. Also check C:\Users\[YourName]\AppData\Local\Temp for ZIP files or folders with recent timestamps—these may contain staged stolen data. Delete anything suspicious, then empty the Recycle Bin.
Run Malwarebytes or Another Reputable Scanner
Download and install Malwarebytes Free (from malwarebytes.com on a clean device if necessary, transferred via USB). Run a full system scan to catch any components or variants you may have missed. Information stealers often drop additional files or create multiple persistence points. Let the scanner complete and remove everything it finds. Consider also scanning with Windows Defender offline scan as a secondary verification.
Check and Reset Browser Extensions
Open each web browser you use and review installed extensions. Remove anything unfamiliar or recently added. Consider resetting your browsers to default settings (this will clear cookies and saved passwords—which you'll be changing anyway). In Chrome, go to Settings > Reset and clean up > Restore settings to their original defaults. Repeat for Firefox, Edge, and any other browsers.
Change All Passwords From a Clean Device
Because CowboyStealer harvests saved passwords, you must assume all credentials stored in your browsers are compromised. Using a different computer, tablet, or smartphone that was never infected, change passwords for email accounts first (they're used for password resets), then banking, cryptocurrency exchanges, social media, shopping sites, and work-related accounts. Enable two-factor authentication wherever possible—this significantly reduces the damage attackers can do even with stolen passwords.
Secure Cryptocurrency Wallets Immediately
If you use cryptocurrency wallets, transfer all funds to new wallet addresses immediately from a clean device. CowboyStealer specifically targets wallet files and seed phrases. Even if you successfully remove the malware, attackers may have already copied your wallet data. Create new wallets with new seed phrases on a device you're certain is clean, then move your assets before the attackers do. Check your transaction history for any unauthorized transfers.
Reboot Normally and Verify Removal
Restart your computer normally (not in Safe Mode) and reconnect to the internet. Open Task Manager again and monitor for any suspicious processes. Check the registry Run keys and scheduled tasks one more time to ensure nothing has reappeared. Run another quick scan with Malwarebytes. Monitor your computer's behavior over the next few days—watch for unusual network activity, unexpected slowdowns, or browser redirects that might indicate incomplete removal or reinfection.
Prevention
- Never download cracked software or key generators. These are the single most common infection vector for information stealers. The "free" software costs far more in stolen credentials and compromised accounts than the legitimate version would have.
- Scrutinize email attachments and links carefully. Verify sender addresses by hovering over the displayed name to see the actual email address. Be suspicious of unexpected invoices, shipping notices, or urgent security alerts. When in doubt, navigate to the company's website directly rather than clicking email links.
- Download software only from official sources. Use the software publisher's actual website or verified stores like the Microsoft Store. Avoid third-party download sites that bundle installers with additional "offers" or search results that lead to lookalike domains.
- Keep Windows and all software updated. Enable automatic updates for Windows, browsers, and security software. Many stealer infections exploit known vulnerabilities that have already been patched.
- Use a reputable antivirus with real-time protection. Windows Defender is adequate for basic protection, but consider Malwarebytes Premium, Bitdefender, or ESET for more robust detection of stealers and other threats. Keep it updated and actually running—disabled security software provides zero protection.
- Store cryptocurrency in hardware wallets. If you hold significant cryptocurrency, invest in a hardware wallet (Ledger, Trezor) that keeps private keys offline where software stealers cannot reach them. Never store seed phrases in text files, screenshots, or browser password managers.
- Enable two-factor authentication everywhere possible. Use authenticator apps (Authy, Microsoft Authenticator, Google Authenticator) rather than SMS when available. This ensures that even if your password is stolen, attackers cannot access your accounts without the second factor.
- Use a password manager instead of browser password storage. While browser-saved passwords are convenient targets for stealers, dedicated password managers like Bitwarden, 1Password, or KeePassXC offer better encryption and security features. They're still vulnerable if your computer is infected, but they're harder for malware to automatically harvest.
When we remove malware from your computer at Computer Repair Roswell, we back our work with a 90-day warranty. If the same infection returns within three months, we'll clean it again at no additional charge. We don't just remove the malware—we identify how it got there and help you prevent reinfection.
Bring It In
Information stealers like CowboyStealer demand immediate attention because the damage continues long after the malware is removed. Even if you successfully delete the files and clean the registry, your credentials remain in the attackers' hands until you change them—and doing that thoroughly across dozens or hundreds of accounts while ensuring you haven't missed anything requires methodical work. If you're uncertain about any step in the removal process, if the malware keeps returning, or if you've already noticed unauthorized account access, professional assistance can save you significant time, money, and stress.
At Computer Repair Roswell, we've cleaned hundreds of information stealer infections and can thoroughly remove CowboyStealer while helping you secure your compromised accounts. We're located at 1322 Hembree Road, Roswell, GA 30076, open Monday through Friday 10 AM to 6 PM and Saturday 10 AM to 4 PM. Call us at (770) 856-1020 or stop by—we'll assess the infection, provide an honest estimate, and get your computer and accounts secured properly. The consultation is always free, and we explain everything in plain English.