IMSI DETACH DoS
In GSM networks that use the IMSI ATTACH/DETACH procedure, the IMSI DETACH message is not authenticated.
A malicious attacker knowing the IMSI or TMSI of a victim can thus send hand-crafted IMSI DETACH messages to a cell, causing the network to assume the MS is no longer present in the network.
This will effectively prevent the delivery of all mobile-terminated (MT) services, such as SMS, voice calls, CSD, ...
This flaw was first discovered in May 2010 by Sylvain Munaut.
#2 Updated by steve-m almost 8 years ago
This issue has also been covered at the "GSM and 3G Security"-talk at Blackhat Asia in April 2001.
See page 9 of the slides of the talk, "De-registration spoofing":