Hi Sacim of Milano:
I don't think of any DOS attack that depends on Open System as opposed to Shared Key 802.11 authentication.
In any event, Shared Key is highly deprecated and is forbidden in Robust Security Networks (RSN). Even no authentication at all, as is optional with Independent Basic Service Sets (IBSS), is more secure than Shared Key.
IEEE 802.11 says:
The Open System authentication algorithm is used in RSNs based on infrastructure BSS and IBSS, although Open System authentication is optional in an RSN based on an IBSS. RSNA disallows the use of Shared Key authentication.
8.2 Pre-RSNA security methods
Except for Open System authentication, all pre-RSNA security mechanisms have been deprecated, as they fail to meet their security goals. New implementations should support pre-RSNA methods only to aid migration to RSNA methods.
18.104.22.168.1 Security association in an ESS
Note 3?¡é?€?¡±IEEE 802.11 Open System authentication provides no security, but is included to maintain backward compatibility with the IEEE 802.11 state machine (see 5.5).
I hope this helps. Thanks. /criss