[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

DoS on QM and how to solve it.



Here's a possible DoS attack on IKE:
Alice and Bob do a Quick Mode exchange using PFS.
Mallory records the first QM packets and replays them after a while.
Result: The receiver needs to do unnecessary DH computations.

Solution:
Alice and Bob should keep a hash table whose keys are the peer, the IKE SA SPI
(Cookie I and CookieR) and the QM MsgId.
Before processing a first QM packet they should consult the hash table to check
that they didn't already have a QM exchange with
the same MsgId and Cookies.
The hash table can be cleared from these entries after the IKE SA is expired.
Note that even though this solution consumes memory (the storage needed for hash
table entries), the amount of memory needed
depends only on the number of QM exchanges negotiated under the IKE SA which is
not controlled by Mallory.





begin:vcard 
n:Zegman;Tamir
tel;fax:+972-3-5759256
tel;work:+972-3-7534606
x-mozilla-html:TRUE
url:www.checkpoint.com
org:Check Point Software Technologies Ltd.;Encryption group
adr:;;3A Jabotinsky St., Diamond Tower;Ramat-Gan;;52520;ISRAEL
version:2.1
email;internet:zegman@checkpoint.com
title:Software engineer
fn:Tamir Zegman
end:vcard

References: