BlackNurse DoS Attacks Can Bring Down Large Servers

Following the news that BlackNurse DoS Attacks Can Bring Down Large Servers Using a Single Laptop, Sean Newman, Director at Corero Network Security commented below.

Sean Newman, Director at Corero Network Security:

“Networking devices, which are not dedicated to DDoS protection, are always likely to be vulnerable to new attack vectors themselves, sooner or later – in this case, it’s a new variant of an old vector!  In fact, BlackNurse is more evolutionary than revolutionary, with the attackers reinventing an old attack vector to exploit this state-exhaustion vulnerability.  The challenge is that most network devices have to participate in the protocols which enable a network to function effectively, which almost always requires state to be maintained in some form. Modern Firewalls, even NGFWs, are no different, being vulnerable to DoS attacks, by virtue of the fact that they are required to hold state as part of their normal mode of operation.

“In this case, it’s trivial for DDoS protection to block the attack.  However, it is just another example of why DDoS protection needs to be treated separately from other networking functions. If organisations deploy dedicated DDoS protection at the network edge, in front of their perimeter security solutions, then state-exhaustion attacks such as these are removed in real-time and no longer impact their infrastructure.”