HackTool:Stowaway is a sophisticated penetration testing and network tunneling tool that has crossed the line from legitimate security research into the realm of malicious exploitation. Originally developed as a multi-hop proxy framework for penetration testers and red teams, Stowaway allows attackers to create complex network tunnels through compromised systems, effectively using your computer as a relay point to hide their true location and bypass network security controls. While the tool itself is open-source and available on GitHub, its presence on a consumer or small-business computer almost always indicates either a breach by an external attacker or intentional misuse by an insider.
Unlike typical malware that steals data or displays advertisements, HackTool:Stowaway operates as infrastructure—it turns your machine into part of an attacker's command-and-control network. This makes it particularly dangerous because you may not notice immediate symptoms while your computer is actively being used to attack others, exfiltrate data from your network, or provide persistent backdoor access to threat actors. The tool's sophisticated evasion techniques and legitimate design origins make it challenging for standard antivirus software to detect and remove.
Threat Profile
| Attribute | Details |
|---|---|
| Family | HackTool / Network Tunneling Proxy |
| Aliases | HackTool.Stowaway, Backdoor:Win32/Stowaway, Trojan:Stowaway (detection name varies by vendor) |
| Platform | Cross-platform (Windows, Linux, macOS); compiled binaries for x86/x64/ARM |
| Discovered | Tool publicly released circa 2020; increased malicious use detected 2021-present |
| Distribution | Deployed post-compromise via other malware, phishing with macro documents, RDP exploitation, supply-chain attacks |
| Persistence | Registry Run keys, scheduled tasks, Windows services, cron jobs (Linux), launch agents (macOS) |
| Primary Capabilities | Multi-hop SOCKS5 proxy, port forwarding, reverse shell, file transfer, traffic encryption, network pivoting |
| Network Behavior | Establishes outbound connections to attacker-controlled servers; creates encrypted tunnels on non-standard ports; may communicate via HTTP/HTTPS to blend with normal traffic |
| Typical Artifacts | Executable files with generic names (svchost.exe, update.exe), configuration files in user temp directories, unusual listening ports, encrypted network traffic patterns |
| Payload Size | Varies by compilation (typically 2-8 MB for Windows binaries) |
| Removal Difficulty | High — requires identifying all components across potentially multiple systems; network-level investigation often necessary |
| Risk to Business Networks | Critical — enables lateral movement and can compromise entire network infrastructure |
How It Spreads
HackTool:Stowaway is not self-spreading malware in the traditional sense. It doesn't replicate like a worm or arrive through common infection vectors like malicious advertisements. Instead, it's almost always manually deployed by an attacker who has already gained initial access to a system through other means. Think of it as a second-stage tool—the attacker uses some other method to break in, then installs Stowaway to maintain access and expand their reach within your network.
The initial compromise that allows Stowaway deployment typically happens through exploitation of weak credentials, unpatched vulnerabilities, or social engineering attacks. Once an attacker has established even limited access, they'll deploy Stowaway to create a stable, encrypted communication channel that's difficult to detect and easy to maintain over long periods. This is why Stowaway infections often go unnoticed for weeks or months—by the time it's installed, the attacker already has a foothold and is using your computer to quietly accomplish their objectives.
Common deployment scenarios include:
- RDP brute-force attacks: Attackers scan the internet for exposed Remote Desktop Protocol connections, crack weak passwords, then install Stowaway to maintain persistent access even if the RDP credentials are changed.
- Phishing with macro-enabled documents: An email attachment containing malicious macros downloads and executes Stowaway as part of a multi-stage infection chain, often after first installing a more recognizable trojan or info-stealer.
- Exploitation of vulnerable web applications: Unpatched content management systems, web servers, or business applications can be exploited to gain server access, after which Stowaway is installed to tunnel into the internal network.
- Supply-chain compromises: In sophisticated attacks, Stowaway may be bundled with legitimate-looking software updates or installed through compromised software distribution channels.
- Insider threats: Malicious employees or contractors may intentionally install Stowaway to maintain unauthorized access to company systems after termination or to exfiltrate data covertly.
- Lateral movement from other infected systems: Once an attacker controls one machine on a network, they use Stowaway to pivot to other systems, installing additional instances to create a web of interconnected tunnels throughout the organization.
What It Does On Your Machine
Once installed, HackTool:Stowaway operates as a sophisticated proxy agent that allows an attacker to route their network traffic through your computer. The tool establishes an encrypted connection to a command-and-control server controlled by the attacker, then waits for instructions. From the attacker's perspective, your computer becomes a "node" in their proxy chain—they can connect to it, use it to access other systems on your network, forward ports to internal services, or simply use it as a relay point to mask their true location when conducting attacks elsewhere.
The practical impact is that your computer becomes infrastructure for criminal activity. If you're on a home network, the attacker might use your computer to scan for other vulnerable devices, attempt to access your router's administration interface, or monitor network traffic to capture credentials and sensitive data from other devices in your household. In a business environment, the consequences are far more severe—Stowaway enables attackers to move laterally across the network, accessing file servers, databases, and other employee workstations as if they were sitting at your desk. The tool's multi-hop capability means attackers can chain multiple compromised systems together, making it extremely difficult for security teams to trace the attack back to its origin.
Stowaway installations typically include persistence mechanisms to survive system reboots and maintain long-term access. The tool may register itself as a Windows service with a generic name like "System Update Service" or create scheduled tasks that restart the proxy agent if it's terminated. Configuration files containing the attacker's server addresses and encryption keys are usually stored in temporary directories or hidden folders. The tool is designed to be stealthy—it consumes minimal system resources during idle periods and generates encrypted network traffic that resembles legitimate HTTPS connections to casual inspection.
On an infected system, you might observe unusual network activity in Task Manager—constant outbound connections to unfamiliar IP addresses, network traffic when you're not actively using the internet, or programs you don't recognize maintaining persistent network connections. The system may experience periodic slowdowns when the attacker is actively using your machine to relay large amounts of data. In some cases, particularly on business networks, administrators might notice unusual authentication attempts, unexpected access to internal resources from legitimate user accounts, or encrypted traffic patterns that don't match normal user behavior.
Manual Removal — Step by Step
Disconnect from All Networks Immediately
Before doing anything else, physically disconnect the infected computer from all networks. Unplug the Ethernet cable and disable Wi-Fi through the physical switch or by turning off the adapter in Windows. If this is a business computer, notify your IT department before proceeding—Stowaway infections often indicate broader network compromise that requires professional incident response. Do not reconnect to the network until the removal process is complete and verified.
Boot Into Safe Mode with Networking
Restart your computer and boot into Safe Mode with Networking. On Windows 10/11, hold Shift while clicking Restart, then navigate to Troubleshoot > Advanced Options > Startup Settings > Restart, and select option 5 for Safe Mode with Networking. This prevents most persistence mechanisms from activating while still allowing you to download security tools if needed. Safe Mode loads only essential drivers and services, which may prevent Stowaway from starting automatically.
Identify and Terminate the Stowaway Process
Open Task Manager (Ctrl+Shift+Esc) and look for suspicious processes, particularly those with generic names like "update.exe," "svchost.exe" running from unusual locations, or processes consuming network resources while generating encrypted traffic. Check the "Details" tab and note the full path of any suspicious executables. Right-click suspicious processes and select "End Task." Be careful not to terminate legitimate system processes—if you're uncertain, note the process name and search for it online to verify whether it's legitimate before terminating it.
Remove Persistence Mechanisms
Open the Run dialog (Windows+R) and type "msconfig" to open System Configuration. Under the "Startup" tab, look for unfamiliar entries and disable them. Next, open Task Scheduler (search for "Task Scheduler" in the Start menu) and review scheduled tasks for anything suspicious—look for tasks that run executables from temporary directories or ProgramData folders with generic names. Delete any suspicious scheduled tasks. Then open Registry Editor (type "regedit" in Run dialog) and navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run. Remove any entries pointing to suspicious executables you identified earlier.
Locate and Delete the Stowaway Binaries
Using File Explorer, navigate to the locations where you found the suspicious executables (commonly in %TEMP%, %LOCALAPPDATA%, or C:\ProgramData). Delete the entire folder containing the Stowaway executable and any associated configuration files. You may need to take ownership of these files if you receive permission errors—right-click the folder, select Properties > Security > Advanced, change the owner to your user account, then apply full control permissions. Empty the Recycle Bin after deletion to ensure the files are completely removed.
Run a Comprehensive Malware Scan
Download and install Malwarebytes Free (from malwarebytes.com) or another reputable anti-malware tool. Update the definitions to the latest version, then run a full system scan. Stowaway is often accompanied by other malware that facilitated its initial installation, so you need to identify and remove the entire infection chain. Quarantine or delete all threats detected by the scanner. Consider running a second scan with a different tool (such as ESET Online Scanner or Kaspersky Virus Removal Tool) to catch anything the first scan might have missed.
Check for Rootkit Components
Download and run a dedicated rootkit scanner such as GMER or Kaspersky TDSSKiller. Sophisticated Stowaway installations may include rootkit components that hide processes, files, or registry entries from normal detection tools. These specialized scanners can detect kernel-level modifications and hidden drivers. If rootkit components are detected, follow the tool's recommendations for removal, which may require additional boot-time scans or specialized removal procedures.
Review and Secure User Accounts
Open Computer Management (right-click Start > Computer Management) and navigate to Local Users and Groups > Users. Review all user accounts on the system. Delete any accounts you don't recognize or didn't create. Check that no unauthorized accounts have administrative privileges. If this is a business computer, coordinate with your IT department to verify that Active Directory accounts haven't been compromised. Change the password for your Windows account to a strong, unique password—assume that any passwords used on this computer may have been captured by the attackers.
Change All Passwords from a Clean Device
Using a different, known-clean computer or smartphone, change passwords for all accounts you've accessed from the infected machine. This includes email, banking, social media, work accounts, cloud storage, and any other online services. Enable two-factor authentication wherever possible to provide an additional layer of security. Assume that any credentials entered on the infected system may have been compromised—attackers using Stowaway often deploy keyloggers or credential-stealing malware alongside the tunneling tool.
Reboot and Verify Complete Removal
Restart your computer normally (not in Safe Mode) and immediately run another full system scan with your anti-malware tool. Monitor Task Manager for several hours after reboot, watching for suspicious processes or unexpected network activity. Check that none of the persistence mechanisms you removed have reappeared. If you're confident the system is clean, you can reconnect to your network—but remain vigilant for the first few days. If suspicious activity returns or you have any doubt about complete removal, the safest approach is to back up your important files to external storage, perform a complete system reinstall, and restore only non-executable files from the backup.
Prevention
- Never expose RDP directly to the internet. If you need remote access to your computer, use a VPN or remote access solution with strong authentication. If RDP must be accessible externally, place it behind a VPN gateway, use Network Level Authentication, implement account lockout policies, and require complex passwords. Consider changing the default RDP port and limiting access to specific IP addresses.
- Apply security updates promptly. Keep Windows, macOS, or Linux updated with the latest security patches. Enable automatic updates for your operating system and all applications. Many Stowaway infections begin with exploitation of known vulnerabilities that have available patches—attackers specifically target systems running outdated software because they know these vulnerabilities can be exploited reliably.
- Use a reputable endpoint protection solution. Install business-grade antivirus or endpoint detection and response (EDR) software that includes behavioral analysis and network traffic monitoring. Consumer antivirus products may miss sophisticated tools like Stowaway because they're designed for legitimate purposes. EDR solutions can detect unusual process behavior, unauthorized network connections, and privilege escalation attempts that indicate post-compromise tool deployment.
- Implement network segmentation. For business networks, segment your network so that compromising one system doesn't provide access to everything. Place critical servers on separate network segments with strict firewall rules controlling what can access them. Use VLANs to isolate guest networks, IoT devices, and workstations from servers containing sensitive data. This limits the damage attackers can do with tools like Stowaway that rely on lateral movement.
- Monitor for unusual network activity. Implement network monitoring that alerts you to unexpected outbound connections, traffic to unusual ports, or data exfiltration patterns. Tools like Stowaway generate persistent encrypted connections to external servers—network monitoring can detect these patterns even when endpoint security misses the tool itself. Look for connections to non-standard ports, unexpected geographic locations, or communication patterns inconsistent with normal business activity.
- Practice defense in depth for email security. Since initial compromise often occurs through phishing, implement multiple layers of email security: spam filtering, attachment sandboxing, and user training. Disable macros by default in Office documents and educate users to never enable macros in documents received unexpectedly. Consider implementing email authentication standards (SPF, DKIM, DMARC) to reduce spoofing attempts.
- Require strong authentication everywhere. Use complex, unique passwords for all accounts and enable multi-factor authentication on every service that supports it. Password reuse is catastrophic when dealing with sophisticated threats—if attackers compromise one account, they'll immediately try those credentials everywhere else. For business environments, implement single sign-on with mandatory MFA to centralize authentication and make credential theft less valuable to attackers.
- Conduct regular security audits. Periodically review user accounts, installed software, startup items, scheduled tasks, and Windows services on all systems. Look for anything you don't recognize or can't verify as legitimate. Many Stowaway infections persist for months because nobody looks at what's actually running on the system—regular audits help catch unusual activity before it leads to major compromise.
Bring It In
HackTool:Stowaway represents a level of threat sophistication that exceeds typical consumer malware. This isn't adware or a browser hijacker—it's infrastructure-grade tooling used by advanced attackers to maintain persistent, hidden access to compromised systems and networks. If you've found Stowaway on your computer, you're dealing with a targeted attack or a broader network compromise that requires professional remediation. Attempting DIY removal while connected to the internet risks alerting the attackers and prompting them to deploy additional malware or take destructive action before you can fully secure your system.
At Computer Repair Roswell, we've handled sophisticated malware incidents including APT tools, ransomware, and network intrusions. We understand that Stowaway is rarely the only component of an attack—our technicians will thoroughly investigate your system to identify how the initial compromise occurred, what other malware may be present, and whether your data has been accessed or exfiltrated. We can perform forensic analysis to determine the scope of compromise, clean all infections, secure your system against reinfection, and help you understand what happened and how to prevent it going forward. Don't risk incomplete removal or ongoing surveillance of your computer and network. Call us at (770) 674-6311 or stop by our shop at 1370 Center Dr, Roswell, GA 30076. We're here Monday through Friday, and we'll treat your security incident with the seriousness and urgency it deserves.