8 Signs Your PC Might Be A Zombie


Zombies are making a killing on TV (The Walking Dead), in movies (World War Z), and in books (Pride and Prejudice and Zombies). There’s even a zombie game/fitness app, Zombies, Run!

But zombies aren’t so entertaining if your computer becomes one.

In PC terms, a zombie is a computer that’s been taken over without the owner’s consent by a third party (or group of people). Once your computer is among the living dead, it often becomes part of a botnet, or a network of other zombie computers. Rogue hackers control botnets to perform orchestrated denial of service (DOS) attacks and to widely spread email spam and malware, among other misdeeds.

Botnet attacks have been around for a long time but are becoming increasingly more sophisticated. So far this year, there have been several high-profile cases that illustrate the power of botnets. Through the global ‘Pony’ botnet attack, for instance, criminals stole about $220,000 in bitcoins and other digital currencies. And a large botnet recently infected Internet-connected home appliances —including refrigerators!—to send out more than 750,000 malicious emails.

Here’s the really scary part: Your computer could be part of a botnet, and you might not even be aware of it. And if your PC doesn’t have an antivirus protection and two-way firewall, you’ve just increased the chance that your PC could be a zombie. Here are 8 signs your computer might be a zombie, and what you can do to bring it back to the land of the living.

8 Signs Your PC Might Be a Zombie
1. Your computer’s performance is noticeably slower, even when you don’t have many applications open. Criminals want your computer to carry out illegal actions, and those actions require the use of your computer’s processor and network. So if your computer and/or your Internet connection speed have become sluggish, it may be because of a zombie.

2. You receive unexplained error messages.

3. Your computer crashes frequently.

4. You discover messages in your outgoing email folder that you didn’t send. A tip-off might be if you receive bounce-back notifications from people you don’t know or haven’t emailed.

5. It takes your computer longer to shut down and start up.

6. You discover an unexpected loss of hard disk (or flash storage) space.

7. Your Web browser frequently closes for no obvious reason.

8. Your access to computer security websites is blocked.

How to ‘Kill’ a Computer Zombie
If your PC has become a zombie, there may be ways to resurrect it.

• Update your antivirus and/or anti-spyware software and scan your computer’s hard drive to find and remove the malware. Keep in mind some types of malware will prevent your antivirus software from running. In that event, download additional antivirus software and try to run each one until you find a program that will get past the zombie’s self-defenses.

• Often, zombie/bot malware hides from security software scanners by installing a rootkit. A rootkit is a stealth piece of software that’s usually malicious. There are free rootkit detection software programs you can download.

• Set your computer’s personal firewall to its maximum-security level. This will require applications seeking access to the Internet to notify you, enabling you to track all incoming as well as outgoing traffic. In turn, this can help you identify repeated requests from the same application to access just a few destinations—a telltale sign the application is a zombie.

• If that’s the case, do a search of the application’s name to see if others have identified it as malware. Try to create a list of all files associated with the suspicious application and where they’re located on your storage drive. Remove the application and any related files immediately and restart your computer. You may have to do this several times, because one piece of malware may have several variants on the same computer.

• You’re not going to like this one, but here goes: If you’ve discovered your computer is a zombie and want to make sure you’re completely zombie-free, you should completely wipe the hard drive or flash drive and reinstall the operating system and applications. Make sure your important files are backed up first, of course.

• Once you’ve restored your computer’s storage drive, applications, and documents, run your security software again just to make sure nothing is amiss.

Better Safe Than Zombified
If your computer has become a zombie, it’s probably because you clicked on a malicious file attachment or installed an application you weren’t 100 percent sure about.

To reduce the risk of your computer being compromised again, keep your security software running and updated and your personal firewall at maximum level. Check emails with file attachments closely; you can often tell that the sender didn’t actually email it to you by the stilted language, improper spelling, or other signs. Delete spam email messages without opening them. Don’t download applications if you have any concerns about their safety.

If you take these preventative steps, you can spend less time worrying about your computer and more time watching The Walking Dead. That’s the kind of zombie we like.

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21 comments on “8 Signs Your PC Might Be A Zombie

  • Occasionally, I have some of the zombie symptoms that are reported as malfunctioning drivers. Malware may actually be attacking weaknesses in the drivers causing them to fail in a way favorable to the malware intent. If a program is slow to close for no obvious reason I force closure with the task manager. If that fails to occur promptly I force shutdown with manual switch, power back up in safe mode and run the whole suite of anti-malware programs to scan everything including use of advanced heuristics. The OS is robust enough that a properly installed system will not be corrupted by this. Stealth features in the security suite will find the offending elements no matter where they hide. The downside is that this takes time proportional to how much data I have that is executable or potentially hides an executable. It may take several hours. Sometimes it is quicker to take the system drive out and connect to another uncorrupted system as a data drive to scan. If the system does not boot after re-installing I pop in rescue media to replace corrupted files with backups. Firewalls will not stop cleverly devised unknown threats no matter what settings you use that don’t stop all access, thus the term “suspicious activity”. Avoiding actions that lead there may be the only line of defense that works.

  • Stuart Woolman says:

    Whenever I type, it slows to a crawl to appear on screen and I can’t do anything else.


    • ZoneAlarm says:

      Not necessarily. A number of things could contribute to slowness on your computer, including your OS and the specifications of your computer itself. Also, if you’re running an up-to-date security software and practice safe web browsing, usually you should be pretty secure. However, if you do the exact opposite, you put your PC at high risk for malware infection, which includes possibly being a zombie for a larger botnet.

  • Don’t fight with zombies. Just wipe the drive and reinstall Windows. Even if you don’t have malware, if your Windows installation is a couple of years old, reinstalling the OS can bring it back from the deadish.

  • I’d also add that if removing persistent malware that prevents the computer from connecting to security websites via internet, best thing to do is install the antivirus, registry cleaner and antimalware software of choice on a flash drive using an uninfected computer first, then boot the infected computer in SAFE MODE and run it all while the computer is in the safe mode.

  • Duke of URL says:

    To Paul: “If a program is slow to close for no obvious reason I force closure with the task manager. If that fails to occur promptly I force shutdown with manual switch, power back up in safe mode and run the whole suite of anti-malware programs to scan everything including use of advanced heuristics.”
    Thank you – although I am a fanatic about running safety scans frequently, I’dn’t thought of doing it in Safe Mode. Gonna be doing that weekly from now on.

  • Paul: thank you so much for sharing the safe mode concept except the fact that I have to figure out how to do it on Win8 platform at office and Win7 at home, glad that you shared that piece of advice

  • Henry Hertz Hobbit says:

    Although much of the advice may hold for the old-style bot-ware, the one created by the group I dubbed PerniciousMalware (nee PeskySpammer) won’t cause any problems at all, initially. The infection malware is usually classified as Upatre. It is a hybrid Zeus mini down-loader. It installs its own SMTP outbound mail-sender and does not use your email accounts. It sends out enough spam to keep a brisk business going but not so much that either you or your ISP will notice it. When they get the idea or after about 2-4 months they rob your finance accounts (they have a key logger among the other tools), change your finance account passwords if they can and THEN they savage your machine.

    Too much of this advice focuses on strange behavior of your machine. While that does inform you something is bad, it does not preclude your machine is one of the new “silent” zombies.

    • ZoneAlarm says:

      Possibly, or you might have some other malware. But it’s tough to say. If you have an up-to-date antivirus and firewalla and are vigilant about websites you go to or files you download, then it might be that your PC is old or might have other issues. If you do not have an up-to-date antivirus and firewall and just rummage the web without care, then your PC has a higher chance of being infected.

  • Off topic, but the mention of wiping and reloading Windows reminded me and I thought I’d throw this in whilst I think of it.

    I’ve been running ZA for years and of late I’ve noticed that after a wipe and reload when everything’s running at full speed and I start reloading my regular software, when I reload ZA everything slows down a bit. Is that normal?

    • Be sure that when you wipe and reload your Windows that you uninstall the pre-existing security that came with your PC, even if it has expired. Running ZoneAlarm (which one?) along with pre-existing security software is likely to cause problems and lag.

  • I was told by a network admin that my laptop had some malware that was shutting down whatever wireless network I connected to due to DOS. I’ve run Mcafee and Malwarebytes. Malwarebytes found three files that I quarantined, but it didn’t seem to help.

    Anyone have any ideas?

  • Hey there, You have done a fantastic job. I’ll definitely digg
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  • Sue Adriaansen says:

    We’re continously being dos attacked even after changing IP addresses multiple times and reformatting pc’s several times. The attacks are back within seconds. We also restarted nbn modem several times. We ran every security , malware and anti virus you can think of and nothing is found on the pc’s. We’re at a point we’re our computers don’t see the modem and vice versa. Any help would be appreciated.This is happening on an Optus nbn home network.


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