Disable Hidden File Extensions, Or Not?

In the world of technology, the accelerating rate of change is so fast, the environmental changes so rapid, that looking back just 3 years, for example, is akin to looking back into ancient history.

Even so, there are some characteristics of computing where the old truism “the more things change the more they stay the same”, are entirely relevant – and, the fundamentals of system security is a singular example.

One of the principals of system security – one which is rarely referred to is – the need to understand file extensions – and, more particularly – why it is file extensions should NOT be hidden.

Dave Brooks, a highly competent computer pro, and a popular guest writer here, addressed this issue in a guest post (ahem), 3 years ago. This article is every bit as important today, as it was when it was first posted. Perhaps, even more so.

Here’s what Dave had to say:

One of Bill’s security recommendations (among the many that he tries to pound into the heads of his readers), is to disable the hiding of file extensions for known file types.

I will explain why this is important and how it can protect you. This can get a bit complicated for the novice user, so I’ll try to make it easy to understand.

Firsts things first. What is a file extension? File extensions tell the operating system what type of file it is dealing with, which in turn determines what application is opened when you double click the file.

Adobe PDF documents have a PDF extension, MP3 audio files have the MP3 extension, video files use a number of extensions such as AVI, MPE, MPEG, WMV, and so on. Windows keeps track of what file extensions should be opened with which application, if you rename a file and delete its extension, Windows no longer knows what type of file it is and will not be able to open it.

When working with Windows, almost all files have an extension, this is the 3 or 4 characters after the LAST “.” (dot or period) in the file name. Why is the word LAST in upper case? Because file names can have more than one “.” in them, and this is where your ability to see these extensions can save you.

For example, consider this file named “Invoice.doc”. For many people they would immediately know this is a standard Microsoft Word document. If your PC is set to hide known file extensions then your computer would display the file in a Windows Explorer window, or email attachment, as “Invoice”, hiding the 3 digit extension.

The problem here is, a Trojan can come in as an email attachment as a compressed file, or an executable called Invoice.doc.exe. Remember, only the digits after the LAST “.” are important to the file type, so even though you see Invoice.doc, the file actually has an exe extension, making it an exe or program.

If you have your PC set to hide extension, you would see the file name as “Invoice.doc”, even though the actual extension (which is hidden by Windows) is exe. Another trick is to give the file an icon that makes it look like it’s a Word document to fool unsuspecting users even more.

So you can see, if you disable hidden extensions, you will be able to see the actual file extension, not the one the Trojan wants you to see, and you will be able to better determine if the file is in fact what it is claiming to be.

To unhide these hidden extensions;

1. Go to start>Control Panel

2. Click on >Folder Options

3. Now go to >View tab> Then uncheck the box “Hide extensions for known file types” >click Apply>then OK. That’s it done.

Now you can see the file extensions on all file types.

 

Note: If you come across a file type (extension) that you don’t recognize, the website FILExt will tell you. Simply enter the “.abc” and FILExt will tell you the program that created it and, recommend how to open it.

Bio: Dave Brooks is a professional Computer Technician from New Hampshire, USA. Dave has now become a regular guest writer who’s last article “Let’s Talk About Backups” was a huge hit.

Drop by Dave’s site at Tech-N-Go, and checkout the Security Alerts.

Think You’re Immune From Online Fraud? Maybe Not!

Guest writer Dave Brooks, a vastly experienced computer Tech from New Hampshire, who is an expert at online safety, shares this chilling story on why even exercising proper security measures won’t guarantee your online financial safety.

Bill is constantly trying to pound security into his reader’s heads, and with good reason, but unfortunately, no matter how careful you are, there are things that are beyond your control when buying stuff online.

Case in point: at Bill’s request I’m going to relay a recent unnerving personal experience, if only to show that even the most security conscious are still at risk.

I’m very online safety/security conscious and I buy online only from reputable, well known stores. My online bank account password looks like an alien language, my ATM pin is 8 digits long (compared to 4 or so many people use), and I monitor my account closely.

Even so my ATM card number was recently used, in the middle of the night, in Georgia, while I was sound asleep in New Hampshire. Luckily Bank of America has decent monitoring, and I have a ton of alerts set up to email me when certain things happen with my account.

I woke up in the morning to find an alert that my card was used while I was asleep, and an email from Bank of America that they had detected suspicious activity on my account, had frozen the transaction, and placed a lock on my account to prevent further activity.

The charge was for the amount of $1.22; it’s apparently common practice by those that use stolen card numbers to make a small charge such as this to confirm that the number is good before using it to make larger purchases.

Thanks in part to my diligent monitoring, and Bank of America’s account monitoring system, the thieves were never able to get to step two and spend my hard earned cash on god knows what.

A call to the number provided in the alert email I got from the bank (after confirming it was in fact their number by matching it up on the Bank of America website; phishing emails are pretty convincing nowadays!), confirmed the illegal activity. Bank of America cancelled my ATM card, and cancelled the charge, and a trip to my local bank branch netted me a new ATM card.

My number was likely stolen from a hacked online database of a company that I had made an online purchase from in the past, but there’s no way to confirm this – it could have just as easily been a dishonest employee from a local store where I used my card.

I have since opened a second account with an ATM card, and use only that account for online purchases, (I had been contemplating doing this for a year or more or more, but never did),

I keep a balance of about 5 bucks in it, and when I want to buy something online, I transfer the purchase amount from my main account to the “internet” account to cover it. At least that way, my main account is less exposed, and if it happens again I’ll be able to determine if it was the “internet” or “local purchase” that led to the compromise.

Bottom line here is, even though you think you’re safe, if you purchase stuff online, your bank or credit card info is out there for the taking. The best you can do is keep a close eye on your accounts for suspicious activity, and try to minimize possible damage that might be done if your card number is stolen.

Guest Writer: This is a guest post by Dave Brooks a professional computer technician from New Hampshire, USA. Dave has become a regular guest writer, who’s articles are always a huge hit.

Pay a visit to Dave’s site at Tech-N-Go, and checkout the Security Alerts.

If you found this article useful, why not subscribe to this Blog via RSS, or email? It’s easy; just click on this link and you’ll never miss another Tech Thoughts article.

Online Dangers – Even a Tech Can Get Taken

Think you’re immune from online fraud? Do you believe – “It could never happen to me”? Read what guest writer Dave Brooks, a vastly experienced computer tech from New Hampshire, has to say about what happened to him.

Bill is constantly trying to pound security into his reader’s heads, and with good reason, but unfortunately no matter how careful you are, there are things that are beyond your control when buying stuff online.

Case in point: at Bill’s request I’m going to relay a recent unnerving personal experience, if only to show that even the most security conscious are still at risk.

I’m very online safety/security conscious and I buy online only from reputable, well known stores. My online bank account password looks like an alien language, my ATM pin is 8 digits long (compared to 4 or so many people use), and I monitor my account closely.

Even so my ATM card number was recently used, in the middle of the night, in Georgia, while I was sound asleep in New Hampshire. Luckily Bank of America has decent monitoring, and I have a ton of alerts set up to email me when certain things happen with my account.

I woke up in the morning to find an alert that my card was used while I was asleep, and an email from Bank of America that they had detected suspicious activity on my account, had frozen the transaction, and placed a lock on my account to prevent further activity.

The charge was for the amount of $1.22; it’s apparently common practice by those that use stolen card numbers to make a small charge such as this to confirm that the number is good before using it to make larger purchases.

Thanks in part to my diligent monitoring, and Bank of America’s account monitoring system, the thieves were never able to get to step two and spend my hard earned cash on god knows what.

A call to the number provided in the alert email I got from the bank (after confirming it was in fact their number by matching it up on the Bank of America website; phishing emails are pretty convincing nowadays!), confirmed the illegal activity. Bank of America cancelled my ATM card, and cancelled the charge, and a trip to my local bank branch netted me a new ATM card.

My number was likely stolen from a hacked online database of a company that I had made an online purchase from in the past, but there’s no way to confirm this – it could have just as easily been a dishonest employee from a local store where I used my card.

I have since opened a second account with an ATM card, and use only that account for online purchases, (I had been contemplating doing this for a year or more or more, but never did),

I keep a balance of about 5 bucks in it, and when I want to buy something online, I transfer the purchase amount from my main account to the “internet” account to cover it. At least that way, my main account is less exposed, and if it happens again I’ll be able to determine if it was the “internet” or “local purchase” that led to the compromise.

Bottom line here is, even though you think you’re safe, if you purchase stuff online, your bank or credit card info is out there for the taking. The best you can do is keep a close eye on your accounts for suspicious activity, and try to minimize possible damage that might be done if your card number is stolen.

Guest Writer: This is a guest post by Dave Brooks a professional computer technician from New Hampshire, USA. Dave has become a regular guest writer, who’s articles are always a huge hit.

This article is Dave’s response to today’s article “How to Conduct Online Banking Safely”.

Thank you Dave for such a quick response – a great article, crafted quickly.

Pay a visit to Dave’s site at Tech-N-Go, and checkout the Security Alerts.

If you enjoyed this article, why not subscribe to this Blog via RSS, or email? It’s easy; just click on this link and you’ll never miss another Tech Thoughts article.