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WPA-TKIP Now Vulnerable to Attack

In my How to Secure Your Computer series of articles, I issued Maxim #13, “WiFi Security–The Only Way is WPA“. However, TKIP–which is one of the protocols used under the WPA certification standard–is now vulnerable to attack, so I feel it prudent to modify my stance a bit and shed a little light on the subject. Certain media reports would have you believe that WPA has been cracked; this isn’t the case. (See “WPA Not Cracked, But Still Vulnerable.”) Steve Gibson’s latest episode (#170) of Security Now! explains in great detail the TKIP hack and why it’s much to worry about–at least, not yet.

Under the WPA/WPA2 standards, a wireless access point or router can use either TKIP (Temporal Key Integrity Protocol) or AES-CCMP (Advanced Encryption Standard, Counter Mode/CBC MAC Protocol). TKIP is an enhancement of WEP that utilizes the RC4 stream cipher with 128-bit keys for encryption and 64-bit keys for authentication; CCMP provides much stronger protection because it uses AES (Rinjdael) encryption.

Two German researchers, Martin Beck and Erik Tews, recently found a way to crack TKIP. They use what is called a chopchop attack, which attempts to decrypt packets byte by byte. You can read all about it in their white paper, “Practical attacks against WEP and WPA” so I won’t go into the details here.

While there doesn’t appear to be much an attacker can do at this point, the attack is a harbinger of things to come and now would be a good time to log into your wireless router and see what’s up. I discovered that mine doesn’t support AES-CCMP, only TKIP, so I need to upgrade the firmware. I recommend that everyone do one of the following: 1. Switch your current WPA configuration to AES-CCMP if it’s supported; 2. Upgrade the firmware in your router so it supports WPA2 with AES-CCMP;  3. If neither of those is possible, or, heaven forbid, your router only supports WEP, replace it with one that’s WPA2 compliant and use AES-CCMP.

Does Encryption Have You Complacent About Physical Security?

There’s no question that data security is senior to physical security. The real value in a stolen laptop or PC isn’t in the hardware, it’s in the data. Sure, some druggie might steal your laptop and sell it for a fix, but the real danger lies in the thief who knows the value of the files that are stored on it. If it’s a personal laptop, the passwords to your online banking site, credit card numbers, Social Security number–probably everything about your identity–may be stored on it. If it’s a corporate laptop, depending on who you work for, there could be valuable customer information complete with credit card numbers or other proprietary information that a thief or corporate spy could capitalize on.

But physical security is only slightly less important. Don’t get complacent thinking that you’re OK just because your data is secure. It’s an expensive proposition to replace that data, so you must take steps to prevent theft of your hardware.

Encrypting your data is analogous to hiding it. So hide your laptop. Chain down your PC. Make it as difficult as possible for a thief to steal it. I keep my PC in a locked room when I’m not nearby and I maintain the attitude that someone’s waiting around the next corner to steal my laptop. So, it’s always either in a secure area or with me–and I mean within a couple of feet of me. I rarely leave it in my car and if for some reason I must, I lock it up in the trunk. I never leave it overnight in the office. Out of sight, out of mind. There are other physical precautions you can take as this Security Focus article outlines.

And let’s not forget about removable and external storage devices; hide them, too. I’ll cover that in a future article. For now, I leave you with Maxim #8:

Physical security is almost as important as data security. Make it as difficult as possible through any physical means for a thief to steal your hardware. Rules of thumb: Lock it up and lock it down; out of sight, out of mind.

If Your Laptop is Stolen, Will Your Identity be Stolen?

We frequently hear news of a laptop holding sensitive information having been stolen. Bad in itself, but the reports often note that the information was unencrypted. Doubly bad. The news rarely focuses on personal laptop thefts, however because there’s no news value in reporting the loss of Joe Citizen’s personal files; nothing of value there, they think. But Joe’s entire life savings may soon be wiped out if he has ever used that laptop for online banking or other financial transactions.

Recently, a friend of mine (who shall remain nameless for security reasons) had his laptop stolen out of his car. Fortunately, he had just purchased it and there was nothing of value on it, but there could have been–he’s an oil company executive. Modern thieves know that if they can get their hands on a computer holding sensitive information — particularly bank or credit card information — they can sell that computer for tens or hundreds of times the value of the hardware. The hardware is virtually worthless to them. From the thief’s point of view, any laptop sitting on the seat or floor of a decent car or a desktop PC in a middle class home office could belong to someone who has access to valuable information.

But, if the data is encrypted, the thief is out of luck.

I’ll cover physical security later. For now, I present Maxim #7:

If you store sensitive information on a PC or laptop, even if it’s only personal information, encrypt the folders or drives where the information is stored and use an unguessable passphrase as the encryption key.