Wireless security has improved over the years, but wireless networks are still susceptible to vulnerabilities. If you’re planning to take the Security+ exam, you should have a basic understanding of securing a wireless network.
For example, can you answer this question?
Q. Management asks you if you can modify the wireless network to prevent users from easily discovering it. Which of the following would you modify to meet this goal?
A. CCMP
B. WPA2 Enterprise
C. SSID broadcast
D. MAC address filter
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Change Default SSID
Wireless networks are identified by a service set identifier (SSID), which is simply the name of the wireless network. Many WAPs come with default SSIDs. For example, the default SSID of some older Linksys WAPs is “Linksys” or “linksys-g.” Some newer WAPs force you to enter the name of the SSID when you first install it and do not include a default. From a defense-in-depth perspective, it’s a good idea to change the name of the SSID if a default is used. It simply gives attackers less information.
For example, if a war driver sees a wireless network with a SSID of Linksys, the attacker has a good idea that the network is using a Linksys WAP. If the attacker knows about specific weaknesses with this WAP, he can start exploiting these weaknesses. On the other hand, a WAP with a SSID of “Success” doesn’t give the attacker any clues about the WAP.
Disable SSID Broadcasting or Not
One of the goals of 802.11 wireless networks is ease of use. The designers wanted wireless computers to be able to easily find each other and work together. They were successful with this goal. Unfortunately, attackers can also easily find your networks. By default, WAPs broadcast the SSID in cleartext, making it easy to locate wireless networks.
At some point years ago, someone stated that the SSID was a password (not true!), and many information technology (IT) professionals latched onto the idea that you can increase security by disabling the SSID broadcast. Others say that the SSID has nothing to do with security and disabling the broadcast reduces usability but does not increase security.
As background, WAPs must regularly send out a beacon frame to ensure interoperability with other devices in the wireless network. This beacon frame includes the SSID, and if the SSID broadcast is disabled, the SSID entry is blank. However, even if the SSID broadcast is disabled, the WAP includes the SSID in Probe responses sent in response to Probe requests from authorized wireless clients. Because of this, it’s easy for an attacker with a wireless sniffer to listen for the Probe responses and detect the SSID.
In other words, disabling the SSID makes it a little more difficult for attackers to find your network, but not much. It’s almost like locking the front door of your house, but leaving the key in the lock.
Steve Riley wrote in a security blog titled “Myth vs. reality: Wireless SSIDs” that disabling the SSID for security “is a myth that needs to be forcibly dragged out behind the woodshed, strangled until it wheezes its last labored breath, then shot several times for good measure.” In case it isn’t clear, Mr. Riley is in the camp that says you should not disable the SSID. For the record, I agree with him.
For the CompTIA Security+ exam, you should know that it is possible to disable the SSID broadcast and hide the network from casual users. However, an attacker with a wireless sniffer can easily discover the SSID even if SSID broadcast is disabled.
Remember this
The service set identifier (SSID) identifies the name of the wireless network. You should change the SSID from the default name. Disabling SSID broadcast can hide the network from casual users, but an attacker can easily discover it with a wireless sniffer.
Q. Management asks you if you can modify the wireless network to prevent users from easily discovering it. Which of the following would you modify to meet this goal?
A. CCMP
B. WPA2 Enterprise
C. SSID broadcast
D. MAC address filter
Answer is C. You can disable service set identifier (SSID) broadcasting to prevent users from easily discovering the wireless networks. None of the other methods hide the network.
Counter Mode Cipher Block Chaining Message Authentication Code Protocol (CCMP) provides stronger security for Wi-Fi Protected Access II (WPA2) and WPA2 Enterprise adds authentication for a wireless network.
Media access control (MAC) address filtering can restrict access to the wireless network.
