Prevent Viruses Infecting A Memory Card

Viruses can infect a memory card – how to prevent infection. 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 as much about memory cards – viruses can infect them too. Memory cards such as SD and 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 a flash 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/device and connect that via a USB lead – the card can be infected in all cases.

Why Worry? A virus may infect or delete all the data (pictures etc) 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 the 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? Most 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 cannot write data back to the card. Because no data can be written to it, viruses cannot infect the card – data transfer can go one way only.

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 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.

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4 Responses to: "Prevent Viruses Infecting A Memory Card"

  1. Roy says:

    If it’s an Android phone see for a review of free Android antivirus programs.

    Alternatively, if you have multiple devices to protect, it may be worth considering a paid all in one suite

  2. Kikelomo says:

    How can i download antivirus on my memorycard or phone

  3. Tech Head says:

    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?

    • admin says:

      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.