Difference between revisions of "WEP Cracking"
From ivc wiki
Jump to navigationJump to search
| Line 9: | Line 9: | ||
* '''WEP encryption''': 24-bit unencrypted initialization vector + 104-bit key (13 characters/bytes), 128-bit key -> Used to generate RC4 cipher stream -> XOR the message -> Encrypted packets | * '''WEP encryption''': 24-bit unencrypted initialization vector + 104-bit key (13 characters/bytes), 128-bit key -> Used to generate RC4 cipher stream -> XOR the message -> Encrypted packets | ||
* '''ARP replay''': On the basis that the first 12-bytes of ARP packets always stays the same -> Capture one ARP packet -> Inject back to into the network to stimulate traffic -> 10-20000 packets enough ARP packets and initialization vector | * '''ARP replay''': On the basis that the first 12-bytes of ARP packets always stays the same -> Capture one ARP packet -> Inject back to into the network to stimulate traffic -> 10-20000 packets enough ARP packets and initialization vector | ||
* '''Key crack''': Find initialization vector collisions where two ARP ciphertexts are the same -> XOR back first 12-bytes -> Small piece of the pseudo-random RC4 stream cipher is revealed -> use the collected data to gain a factor for statistical attacking each byte in the final 104-bit (13 character) key -> Try key to verify decryption of captured encrypted packets | * '''Key crack''': Find initialization vector collisions where two ARP ciphertexts are the same (2^24 possibilities) -> XOR back first 12-bytes -> Small piece of the pseudo-random RC4 stream cipher is revealed -> use the collected data to gain a factor for statistical attacking each byte in the final 104-bit (13 character) key -> Try key to verify decryption of captured encrypted packets | ||
== References == | == References == | ||
Revision as of 23:22, 25 August 2009
WEP is infamously known as the broken wireless security protocol. A design flaw was discovered in 2001 and after several cascading discoveries it's now possible to crack a WEP protected network within minutes. WPA is the successor to WEP and features a better but not perfect security protocol.
Background
There are now many sources that describe the vulnerability in detail and APR replay to generate traffic, but this is a short summary. For an throughout explaination on how WEP is implemented and the vulnerabilities, see the link below.
Sections:
- WEP encryption: 24-bit unencrypted initialization vector + 104-bit key (13 characters/bytes), 128-bit key -> Used to generate RC4 cipher stream -> XOR the message -> Encrypted packets
- ARP replay: On the basis that the first 12-bytes of ARP packets always stays the same -> Capture one ARP packet -> Inject back to into the network to stimulate traffic -> 10-20000 packets enough ARP packets and initialization vector
- Key crack: Find initialization vector collisions where two ARP ciphertexts are the same (2^24 possibilities) -> XOR back first 12-bytes -> Small piece of the pseudo-random RC4 stream cipher is revealed -> use the collected data to gain a factor for statistical attacking each byte in the final 104-bit (13 character) key -> Try key to verify decryption of captured encrypted packets
