Prolexic Warns of New DNS Flooder DDoS Attack Toolkit

Prolexic Technologies, a provider of Distributed Denial of Service (DDoS) protection services that was recently acquired by Akamai Technologies, today warned organizations about a new version of an attack toolkit that makes it easy for attackers to launch DNS flood attacks.

The toolkit, DNS Flooder v1.1, makes it faster and easier for malicious actors to launch crippling reflection attacks and will likely be widely adopted in the DDoS-as-a-Service market, potentially increasing the number of attacks,” the company said in a threat advisory.

According to Prolexic, the new toolkit enables attackers to buy, set up and use their own DNS servers to launch reflection attacks without the need to find open and vulnerable DNS servers on the Internet. This expedites the availability of the DNS botnet, enabling malicious actors to launch large cyber attacks without having to spend considerable time and resources building an army of bots through malware infections.

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

Prolexic said that some of its customers have been hit by attacks stemming from the DNS Flooder toolkit over the last six months, and in some cases, the attacks have had amplification factors of 50 times the originating bandwidth.

“This tactic generates resource records that contain large responses (more than 4,000 bytes) when queried with an ANY (255) request from the spoofed IP address,” the advisory explained. “The responses to these ANY requests result in amplified attack payloads. The technique basically crafts requests with record type ANY, which then will elicit responses that are larger in size and directed at the targeted victims.”

According to Prolexic, The DNS Flooder toolkit uses the following multi-step process to launch DDoS attacks:

1. The toolkit spoofs the IP address of the intended target and creates a DNS request, which is sent to attacker’s DNS botnet.

2. The attacker’s DNS botnet sends an extended DNS (EDNS) response back. The EDNS response includes more data than the DNS request (amplification). Because the IP address used in the request was spoofed, the response is reflected back to the attacker’s target.

3. The toolkit loops multiple times, reflecting and amplifying the response to the target with each loop.

Prolexic’s threat advisory, which includes a series of indicators, source code analysis, toolkit functions, malicious payloads and mitigation advice is available here in PDF format.