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Noticed some minor performance decrease, decided to install the process explorer described here: https://security.stackexchange.com/questions/76100/how-to-find-processes-that-are-hidden-from-task-manager

Found a hidden process taking 80% of CPU and impersonating notepad.exe, with this command line:

"C:\windows\notepad.exe" -c "C:\ProgramData\fWyfnSWdrs\cfgi"

Checked that folder, found something that looked like config files, one cant open, used by process, others have this (I've removed user guid):

{"algo": "cryptonight",
"background": false,
"colors": true,
"retries": 5,
"retry-pause": 5,
"syslog": false,
"print-time": 60,
"av": 0,
"safe": false,
"cpu-priority": null,
"cpu-affinity": null,
"threads": 8,
"pools": [

    {
        "url": "185.144.29.36:5450",
        "user": <GUID HERE, REMOVED BY ME>,
        "pass": "x",
        "keepalive": false,
        "nicehash": false,
        "variant": 1
    }
],
"api": {
    "port": 0,
    "access-token": null,
    "worker-id": null
}
}

Some googling and this looks like cryptocurrency mining setup. Tried to kill process - it comes back immediately. Checked register for the folder name and windows services - cant find what starts it.

Tried a couple of other antiviruses - they don't pick it up.

I don't want to "nuke it from orbit" since this machine is nothing special, enough would be to just make it stop.

How do I find what starts this and kill it?

I would also like to know how I got it, the config files are from 20 days ago, checked my installations and cannot see anything from that time. Any tips/links on how to figure this out are appreciated.

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  • I would run Process Monitor - docs.microsoft.com/en-us/sysinternals/downloads/procmon , from there you can see the parent process that launches it. If there is another "watchdog" process. Maybe you could use the suspend process option in Process Explorer to "kill" the pair? Jul 11, 2018 at 20:31
  • What do you mean by "tried a couple of antiviruses"? Does your computer have active and real-time antivirus running? What other tools did you use? What is likely happening is that another process is watching the cryptomining process and restarts it. This watcher process could also have its own watcher. Sometimes these watchers hide themselves (they can be quite clever, really). Jul 11, 2018 at 20:37
  • The problem here is that you have an active unwanted program on your computer that has gained deep system access. Your computer is completed compromised and should not be trusted again. It is even possible that the virus has gained access at a level that a full system wipe and reset will not remove, though that is less likely. I would highly recommend that you back up files that you wish to save, and then fully wipe the hard drive and re-install Windows. This is the best and safest course of action given then symptoms you have described. Jul 11, 2018 at 20:38
  • Further, Windows 7 is no longer actively supported by Microsoft and you need to replace it. Your computer will continue to be more and more vulnerable to viruses and malware the longer you run out of date software. If you do not wish to purchase a newer license of Windows, there are other viable options that will remain modern and capable without the high costs, such as Linux. Jul 11, 2018 at 20:39
  • "Windows 7 is no longer actively supported by Microsoft and you need to replace it." - This is false. You might not be able to call Microsoft for support, but neither could have done that anyways, for an issue like this for free. Windows 7 Extended Support doesn't end until January 14, 2020
    – Ramhound
    Jul 11, 2018 at 20:46

2 Answers 2

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If after killing a process it is re-created then the best course of action is to identify which process has re-created it.

One way to do this is to use Process Explorer from Sysinternals/Microsoft to establish which is the parent process. However, if the parent process is also being terminated to understand this relationship, then using Process Monitor to record the parent/child relationship over time would be good option. For example:

  1. Download Process Monitor and start it capturing.
  2. Kill the process, either from Task Manager or using Process Explorer.
  3. Wait for the process to be re-created.
  4. Stop Process Monitor capturing (Ctrl-E or click on the magnifying glass icon).
  5. Ctrl-T or 'Tools' - 'Process Tree' will display a process tree you can use to find the process in question and identify the process that created it.

Notes: If the parent process is always running, watching in case the child process exits/is killed before re-launching it and likewise the child watches the parent. One trick that may be helpful is to use Process Explorer to suspend the parent and child process before killing them both. This may then enable you do delete the files.

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If a process was killed, then start again, the only option that you have is to KILL it to it's core.

You can figure the location of the app by Opening the file location, and deleting it. If it failed, because of the file is being opened, you can try to kill it and quickly try to delete/rename it.

If this still fails, the only option you have is to go to safe mode, and then deleting the file itself.

BUT... Just to be sure everything is alright, try opening "run" and type msconfig, go to services, "Hide all microsoft services" and kill any services that looks suspicious to you.

Also look into the startup tab. Then go to the file location and delete those yourself, if you found one.

But this goes without saying that your PC is already compromised.

I would scare you by saying Hackers has got your computer under their control, but no, seriously, once they've add a backdoor, you should reinstall your PC. I wont say your safe after doing that, but what can we do about it. We cant just throw our PC away.

You should get a decent antivirus before this happen. That way, in a way you can prevent this from happening again.

-Chibi

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