WEP - Revision history

Franks: /* Fluhrer, Mantin, and Shamir attack */ added link

2013-12-28T11:08:42Z

Fluhrer, Mantin, and Shamir attack: added link

← Older revision		Revision as of 04:08, 28 December 2013
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	== Fluhrer, Mantin, and Shamir attack ==		== Fluhrer, Mantin, and Shamir attack ==

	This is a successful attack (also known as FMS attack) against WEP. It is used by the program aircrack-ng.		This is a successful attack (also known as FMS attack) against WEP. It is used by the program [[aircrack-ng]].
	Due to this WPA was invented supposedly.		Due to this WPA was invented supposedly.


	== Replay attacks ==		== Replay attacks ==

Pbug: /* 24 bit IV */

2013-08-09T09:08:43Z

24 bit IV

← Older revision		Revision as of 02:08, 9 August 2013
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	== 24 bit IV ==		== 24 bit IV ==

	A random 24 bit IV is prepended to every encrypted payload. Given its limited size there will be IV collisions after so many frames. A collision means that the value is the same for two or more IV's. When an IV is the same that means that the keystream between those collision packets is the same as well.		A random 24 bit IV is prepended to every encrypted payload (every frame). Given its limited size there will be IV collisions after so many frames. A collision means that the value is the same for two or more IV's. When an IV is the same that means that the keystream between those collision packets is the same as well.


	== Fluhrer, Mantin, and Shamir attack ==		== Fluhrer, Mantin, and Shamir attack ==

Pbug: /* Injection attacks */

2013-08-08T20:18:51Z

Injection attacks

← Older revision		Revision as of 13:18, 8 August 2013
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	Because the payload has a 32 bit CRC at the end someone can make a replay with an IP address changed. One needs to recompute the IP checksum which is 16 bits and recompute the 32 bit CRC at the end of the plaintext payload (802.11 header + IP packet + CRC32 checksum).		Because the payload has a 32 bit CRC at the end someone can make a replay with an IP address changed. One needs to recompute the IP checksum which is 16 bits and recompute the 32 bit CRC at the end of the plaintext payload (802.11 header + IP packet + CRC32 checksum).
	Most ~~firewalls~~ should allow outgoing packets...		Most home routers should allow outgoing packets...

Pbug: /* Replay attacks */ and collisions

2013-08-08T20:08:55Z

Replay attacks: and collisions

← Older revision		Revision as of 13:08, 8 August 2013
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	== Replay attacks ==		== Replay attacks ==

	Replay attacks are possible with WEP, and they are the reason that people can replay [[ARP]] requests and gather IV's that way.		Replay attacks are possible with WEP, and they are the reason that people can replay [[ARP]] requests and gather IV's (and IV collisions) that way.


	== Injection attacks ==		== Injection attacks ==

Pbug: /* RC4 keystream */

2013-08-08T19:33:20Z

RC4 keystream

← Older revision		Revision as of 12:33, 8 August 2013
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	== RC4 keystream ==		== RC4 keystream ==

	Given a 24 bit IV and either a 40 bit or ~~108~~ bit [[PSK]] an [[RC4]] keystream is derived. A keystream is meant as a stream of bytes that look random but are reproduceable with the same IV and PSK.		Given a 24 bit IV and either a 40 bit or 104 bit [[PSK]] an [[RC4]] keystream is derived. A keystream is meant as a stream of bytes that look random but are reproduceable with the same IV and PSK.

	== 24 bit IV ==		== 24 bit IV ==

Pbug: /* WEP payload */

2013-08-08T19:32:00Z

WEP payload

← Older revision		Revision as of 12:32, 8 August 2013
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	== WEP payload ==		== WEP payload ==

	The plaintext payload has a 4 byte ~~32CRC~~ trailer. The message is then XOR'ed against a keystream. The ciphertext is then prepended by a 24 bit [[IV]].		The plaintext payload has a 4 byte (32 bit) CRC trailer. The message is then XOR'ed against a keystream. The ciphertext is then prepended by a 24 bit [[IV]].


	== RC4 keystream ==		== RC4 keystream ==

Pbug: /* Replay attacks */ injection attacks

2013-08-08T19:29:38Z

Replay attacks: injection attacks

← Older revision		Revision as of 12:29, 8 August 2013
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	Replay attacks are possible with WEP, and they are the reason that people can replay [[ARP]] requests and gather IV's that way.		Replay attacks are possible with WEP, and they are the reason that people can replay [[ARP]] requests and gather IV's that way.


			== Injection attacks ==

			Because the payload has a 32 bit CRC at the end someone can make a replay with an IP address changed. One needs to recompute the IP checksum which is 16 bits and recompute the 32 bit CRC at the end of the plaintext payload (802.11 header + IP packet + CRC32 checksum).
			Most firewalls should allow outgoing packets...

Pbug: some facts as I read them

2013-08-08T19:21:10Z

some facts as I read them

← Older revision		Revision as of 12:21, 8 August 2013
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	WEP stands for Wired Equivalent Privacy and was the first encryption used in [[Wifi]] (WLAN). It has been replaced with WPA2, however most wifi cards still support WEP for whatever reason.		WEP stands for Wired Equivalent Privacy and was the first encryption used in [[Wifi]] (WLAN). It has been replaced with WPA2, however most wifi cards still support WEP for whatever reason.

			== WEP payload ==

			The plaintext payload has a 4 byte 32CRC trailer. The message is then XOR'ed against a keystream. The ciphertext is then prepended by a 24 bit [[IV]].


			== RC4 keystream ==

			Given a 24 bit IV and either a 40 bit or 108 bit [[PSK]] an [[RC4]] keystream is derived. A keystream is meant as a stream of bytes that look random but are reproduceable with the same IV and PSK.

			== 24 bit IV ==

			A random 24 bit IV is prepended to every encrypted payload. Given its limited size there will be IV collisions after so many frames. A collision means that the value is the same for two or more IV's. When an IV is the same that means that the keystream between those collision packets is the same as well.


			== Fluhrer, Mantin, and Shamir attack ==

			This is a successful attack (also known as FMS attack) against WEP. It is used by the program aircrack-ng.
			Due to this WPA was invented supposedly.


			== Replay attacks ==

			Replay attacks are possible with WEP, and they are the reason that people can replay [[ARP]] requests and gather IV's that way.

Pbug: wep

2013-08-07T18:10:03Z

wep

New page

WEP stands for Wired Equivalent Privacy and was the first encryption used in [[Wifi]] (WLAN). It has been replaced with WPA2, however most wifi cards still support WEP for whatever reason.