DNS Flooder toolkit turns DDoS reflection attacks into service, says Prolexic

Criminals experimenting with huge DDoS attacks

Criminals have started using a new DDoS toolkit that offers a simple shortcut for criminals interested in using DNS reflection attacks to pound targets with vast amounts of traffic, mitigation firm Prolexic has warned.

Called DNS Flooder, the v1.1 toolkit is really a way for attackers lacking a dedicated botnet to hire one specifically to generate a reflection or amplification attack of the sort that famously caused trouble when used against anti-spam organisation Spamhaus last year.

Because such an attack requires criminals to source vulnerable DNS servers and to know how to configure them to start a DDoS, DNS Flooder steps in with this initial infrastructure for rent whilst ensuring anonymity.

With the servers in place, the MO is alarmingly simple. The toolkit sends a DNS request to the botnet that spoofs the target network's IP address. This generates a much larger response called an extended DNS response, reflected back to the target's network using the spoofing. The botnet 'loops' this process, generating ever more traffic.

"As the DNS Flooder toolkit uses reflection and amplification techniques, attackers can anonymously launch powerful DDoS attacks with just a handful of servers," said Prolexic president, Stuart Scholly.

"Widespread usage in the DDoS-as-a-Service market is likely and the security community needs to be aware and closely monitor this emerging threat."

The firm had detected DNS Flooder being used in attacks for around six months, he said. The system also seems to work, in some cases generating an amplification level 50 times the originating bandwidth.

Malware has used toolkits to bundle their malevolence into a service for years and DDoS-for-hire is also not a new phenomenon. But the possibility that DDoS attacks at this end of the scale might be offered as a service is a flashing red light for the industry, which doesn't necessarily have an easy (i.e. affordable) way to cope with them.

Coincidentally, only this week attackers tried the same reflection/amplification principle to create a huge DDoS attack on mitigation firm CloudFlare, estimated to have peaked at around 400Gbps, which underlines that this form of DDoS is now a pointer to the future.

Mitigation firm Arbor Networks estimated its size as 325Gbps, and confirmed its target as being French hosting firm OVH.

This had nothing directly to do with DNS Flooder (it attacked NTP not DNS) but the interest in exploiting underlying vulnerabilities in Internet infrastructure and its protocols is clear.

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