How To Prevent Viruses Infecting A Memory Card

How to prevent viruses infecting a memory card.

Viruses often infect USB flash (pen) drives – sharing an infected flash drive between computers is a common way to spread viruses around because they will try to infect every computer they are plugged into.

However, most people (wrongly) do not worry so much about memory cards – but viruses can infect them too.

Memory cards such SDHC cards may be used in cameras, camcorders, mobile phones and sat nav equipment but, when connected to a computer, they are treated exactly the same as USB flash drives – as a storage device.

Because a memory card is treated the same as any external storage drive it can be infected by viruses in exactly the same way.

It does not matter whether you connect the memory card to your computer via an internal card reader, external card reader or just leave it in your camera or phone and connect that via a USB lead – the card can be infected in all cases.

Why Worry about Viruses Infecting a Memory Card?

A virus may infect or delete all the data (pictures or videos) on the memory card meaning that you are unable to access or permanently lose that data.

Also, if an infected memory card is connected to a virus free computer, it can pass on the virus and infect that computer. Even after you have removed any viruses from your computer, connecting an infected memory card can reinfect your computer again.

How To Prevent Viruses Infecting A Memory Card

Many people don’t know about (or have forgotten) the biggest security feature of memory cards – they have a ‘write protect’ sliding switch/tab on the side of the card that tells the operating system (Windows) not to write to the card.

Just like an old floppy disk ;-)

Simply slide the switch to the opposite end and you can read from the card but it cannot be written to i.e. your computer can read and transfer pictures etc from the card onto your computer but it can’t write data back to the card.

Because no data can be written to it, viruses cannot infect the card – data transfer can go in one direction only.

Note: after disconnecting the card from your computer remember to slide the switch on the card back to its original position or you will not be able to take any new photos (they can’t be written to the card while the switch is in write-protect mode).

What About USB Flash Drives?

Flash drives also used to have ‘write protect’ switches making it equally easy to protect against viruses but, unfortunately, they are now very difficult to find and much more expensive than a standard drive.

This step backwards was to cut costs – and complaints from people that they can’t write to the drive, because they forgot to move the switch back…

USB flash drives that do still have the write protect switch are few and far between but one survivor with decent reviews is the Kanguru Flashblu range of drives.

Alternatively, if you only want to protect files on your USB drives from being accidentally modified or deleted on your own computer, see my review of USB Write Protect – a free portable program which can do this.

4 thoughts on “How To Prevent Viruses Infecting A Memory Card”

  1. I heard that the write protect switch on a memory card is not a hardware switch, it relies on the host (Windows) to take note of the switch position and not to write to it.

    Doesn’t that mean a virus could ignore the switch and still write to the card and infect it?

    • In theory you’re right that the switch on a memory card relies on the host (Windows) to recognize the switch and disallow writing to it but, in practice, we have never found a virus that can overcome the Windows/USB controllers and bypass this check.

      We have thrown every type of virus, trojan, rootkit and file infector (like Ramnit which is a really bad one) at it and they have all failed to bypass the switch and infect the memory card – though it can be fun watching the error messages pop up as they fail spectacularly to write to or infect the card ;-).

      We haven’t come across any virus that can do it so our advice remains that, in real life, your best protection when plugging your card into computers is to use the switch to avoid infection.

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