Re:Blacknurse – Low bandwidth ICMP firewall attack
by virtualwhys on Monday November 14, 2016 @01:13PM
(#12951900)
Looks like ASA >= 9.2.4 ships with `icmp unreachable rate-limit 1 burst-size 1`, which is I believe the workaround Cisco suggests:
We recommend that you grant permission for the ICMP unreachable message type (type 3). Denying ICMP unreachable messages disables ICMP Path MTU discovery, which can halt IPsec and PPTP traffic. See RFC 1195 and RFC 1435 for details about Path MTU Discovery
hping3 -1 -C 3 -K 3 -i u20 <target ip>
ofc that assumes you have access to hping/hping3. I plan to check my own server as soon as I can.