WiFi Security Protocols
In today’s world Wi-Fi has become the essential thing in our
daily routine. The wireless networks are also not secure in this digital age.
New flaws and exploits are found on daily basis and Wi-Fi is no exception in
that. Let’s understand the functioning and the flaws present in it.
Before diving deep into the protocols and standards, here is
an overview of Wi-Fi.
Wi-Fi (802.11) - an IEEE wireless communication standard has
14 channels. These channels ranges from 2.412GHz (Channel 1), 2.417GHz (Channel
2) to 2.484 GHz (Channel 14) and 6 modes- Master, Managed, Ad-Hoc, Mesh,
Repeater and Monitor. As we all are familiar with the terminologies- Packets
and Frames, let’s jump onto the main topic- Wi-Fi security Protocols and flaws
in it.
WEP, WPA, WPA2-AES
WEP:
Wired Equivalent Privacy is the security protocol which uses
64, 128 and 256 bit keys. 256 bit key is rarely used. Initialization Vector is
used along with RC4 for the encryption. The interesting fact about WEP is it
uses the CRC (Cyclic Redundancy Check) instead of MAC (Message Authentication
Code).
Where’s the Flaw?
The length of initialization vector is 24 bit and RC4 is the
stream cipher and the same key cannot be used twice. WEP uses a 64/128 bit key
which is concatenated with a 24bit initialization vector (IV) to form the RC4
traffic key.
- 64 Bit key is made of 24bit IV + 48bit key (12 hex
characters)
- 128 Bit key is made of 24bit IV + 104bit key (26 hex
characters)
The content in IV is in plain text and the sole purpose of
IV is to avoid the repetition but the length of 24 bit is too much to ask for
on the busy network. The probability increases to 50% for the repetition of IV
after 5000 packets having 24 bit length.
Here is the WEP schema diagram to illustrate more:
There are 2 ways for
the authentication: Open and Shared Key
-
In Open system any person, regardless of its WEP
keys, can authenticate itself with the Access Point and then attempt to
associate. Right keys are required for the authentication and that’s the only
catch.
-
While in Shared Key, four way handshake happens:
1.
Authentication Request 2. AP acknowledges back
with clear text challenge 3. Challenge Encrypted 4. AP Decrypts and
authenticates client by checking the key
The Share key is less secure because it allows the attacker
to get Initialization Vectors using the challenge through response mechanism.
The attacking methods:
Passive also known as Silence mode:
Sniffing the air for packets without sending any data to the
AP or clients
Active:
Breaking the key while sending data to the AP or client.
WPA:
WPA TKIP (Temporal Key Integrity Protocol) was created after
WEP. The purpose was to close all the vulnerabilities and use the same
hardware. The encryption algorithm remained the same- RC4 but the major change
was TKIP. TKIP basically works by generating a sequence of WEP keys based on a
master key and re-keying periodically before enough volume of data.
Where’s the Flaw?
3 steps are required to crack WPA:
-
Send a De-Auth to AP
-
AP Re-Auth the Client
-
Capture the handshake and brute force it
Beck-Tew attack of WPA:
It allows to decrypt a packet without knowing the key. The Beck-tew
attack is based on the Chop-Chop attack.
So, WPA2 is the best solution than WEP and WPA1 with more
confidentiality.
WPA2 with AES:
WPA2 was built using CCMP (Counter Mode with Cipher Block
Chaining Message Authentication Code Protocol) which is AES based encryption.
However, WPA2 is also vulnerable. It is vulnerable to brute force attack with 4
way handshake. The length and complexity of password is a key factor in the
hack.
How to ensure the Wi-Fi security?
-
Do not connect to Wi-Fi of public places
-
Make sure the password strength is up to the
mark
-
Use WPA2 (AES) as it’s the strongest protocol
currently
-
Make your Wi-Fi network hidden if possible
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