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Case Study: Handling DDOS Attack on Pari-Match

Handling DDOS Attack

So, it’s your turn!
Your sites are going under attack unless you pay 25 Bitcoin.



One day a system administrator of one of our client got an extraordinary e–mail.

Guys from so–called “DD4BC” group treatened the company to start powerfull DDOS attack on the compay’s site. They wanted money and gave the company a day.

“Your sites are going under attack unless you pay 25 Bitcoin.”
“[…]we are giving you 24 hours to get it and pay us.”

they wanted 25 Bitcoins to a predefine account. Obviouly nonbody replied or paid them.


Statistics on botnet–assisted DDoS attacks in Q1 2015 (excerpts from securelist.com):

  • In Q1 2015, 23.095 DDoS attacks were reported, targeting web resources in 76 countries.
  • Most DDoS attacks targeted web resources in China, the USA and Canada.
  • China, the USA and Canada were the countries that faced the largest number of DDoS attacks.
  • In Q1 2015, just like in Q4 2014, bots designed to infect Linux servers were more active than those targeting Windows devices.

Problem Evaluation

Next day the DDoS-ing started as they promised.

The attackers used IP addresses as targets for UDP amplification DDoS attack against customer’s uplinks, so we used BGP blackhole communities to discard traffic at Edge routers of upstream Tier1 ISPs.

Taking into account difference between average daily traffic and traffic when DDoS-ing, we were getting approximally 100 GBit/sec load on the network. Traffic dump shown ~120.000 infected nodes that were producing the DDoS attack itself. This impresses a lot and shows that an average DDoS-er has such considerable resource in hand.

Problem Resolution

The attack was beaten in 10 minutes. The attackers had an IP address as a target for DDoS-ing, so we used BGP protocol to redirect attackers to nowhere:

  1. We captured all traffic hitting router uplinks during attack;
  2. We did BGP blackhole for attacked IP addresses;
  3. We started website on other Uplinks and forwarded traffic via Cloudflare to protect customer infrastructure from UDP flood attack.

That’s all. If you have the same troubles with attackers, call us. We help.


Here you can see geography of the hosts used for UDP amplification attack: