Getting attackers out of a system or network feels like a win. But in many real cases, they come back. Why? Because they leave hidden ways in before you even notice the problem. Ransomware groups like Akira (as noted in CISA's 2025 updates) often plant extra tools or modify settings so they can return if their main access gets blocked.
For individual users and small teams trying to maintain their own security, this presents more challenges, such as losing files, experiencing downtime or being victims of identity theft due to stolen credentials. The important thing to remember is that a great deal of these attacks are not necessarily new attacks; they are, in fact, the same attack being repeated.
Common Real-World Ways They Get Back In
Here are some of the most common methods that cybercriminals have used in the past to regain access to their victims:
1. Hidden scheduled tasks (malware is reinstalled automatically, for example, on a set schedule, or whenever a logged-in user logs in)
2. Starting reg. entries (malicious code executed at start-up without the user knowing)
3. Leftover legitimate remote access programs (unchecked, the malicious code can execute anyway)
4. Accessing an old, known password or token (where criminals can still log in, even with password resets)
5. A web shell (a small script injected into either a website or into an application whose authors unknowingly granted access to)
Practical Tools to Check and Catch This
You don't need enterprise budgets. These free or built-in tools help spot hidden persistence. Many security pros use them daily.
1. Sysmon (Free from Microsoft) A lightweight logger for Windows. It records detailed events like new tasks, registry edits, and process starts. Practical step: Download from Microsoft, install with a basic config (plenty of free community configs online), and check Event Viewer under Applications and Services Logs > Microsoft > Windows > Sysmon. Look for unusual scheduled task creations or registry Run key changes.
2. Sigma Rules (Free) Simple text-based detection rules you can apply to logs. Practical step: Grab rules from GitHub (SigmaHQ/sigma), focus on persistence ones (e.g., "schtasks" or "registry autorun"). Use a free tool like Hayabusa to scan event logs quickly—run it on a USB drive if needed for offline checks.
3. Velociraptor (Free open-source) Great for hunting across one or many computers. It collects evidence fast without much setup. Practical step: Download the portable version, run the server locally or use the standalone client. Search for built-in artifacts like "Windows.Persistence.ScheduledTasks" or "Windows.Registry.Autoruns." A quick hunt often reveals hidden tasks or suspicious registry entries in minutes.
4. Hayabusa (Free) Fast scanner for Windows event logs with Sigma support. Practical step: Run it against exported .evtx files or live logs: hayabusa.exe csv-timeline -d . --output results.csv. It highlights suspicious persistence events clearly.
5. The built-in Task Scheduling Tools of Windows (taskschd.msc) can be used manually by you to look for unknown tasks. The Autoruns utility from Sysinternals (available for free download from Microsoft) scans the startup locations (and shows you weird entries).
All these tools can help you locate most of the common forms of persistence in the context of home or small-office environments, and when conducting a personal forensic investigation.
Steps You Can Take Right Now
1. Scan for obvious signs: Open Task Scheduler and Autoruns. Disable/delete anything unfamiliar (research first—some are legit).
2. Install Sysmon basics: Set it up on your main PC. Review logs weekly for new scheduled tasks or odd registry activity.
3. Run a hunt: Use Velociraptor standalone for a one-time check. Focus on persistence artifacts—takes under an hour on a single machine.
4. Once you have recovered from your infection, it's recommended to change your passwords on a clean device and enable MFA wherever possible. It is recommended to monitor your logs or run a free trial EDR for at least 30 to 60 days.
5. To prevent further issues, utilize strong unique passwords with a password manager; keep your software up-to-date; and do not use any unknown remote access tools.
In practice, running these checks has helped users and small teams spot and block re-entry attempts before major damage.
Key Takeaways
Attackers often leave "insurance" access points. Treat removal as step one, not the end. Use free tools like Sysmon, Velociraptor, and Sigma to verify the system stays clean. Regular quick checks go a long way toward keeping things secure without complexity.
