Largest Ever 400Gbps Distributed Denial of Service NTP Amplification attack hit Cloudfare

Pierluigi Paganini February 12, 2014

Largest Ever 400Gbps Distributed Denial of Service NTP Amplification attack hits Europe servers of anti-DDoS protection firm Cloudfare.

Despite  the Distributed Denial of Service (DDoS) attack is a type of offensive easy to arrange, it is a very insidious threat for web services. A recent analysis revealed that the Distributed Denial of Service attack are increasing in magnitude and frequency, attackers are exploring new tactics, including the Amplification Attack, a technique used to multiply the power of the attack masquerading real source.
This week the attackers have conducted the largest ever Distributed Denial of Service attack, security experts at anti-DDoS protection firm Cloudfare firm revealed that an NTP Amplification attack with a peak of 400Gbps has targeted its European data servers.

Very big NTP reflection attack hitting us right now. Appears to be bigger than the #Spamhaus attack from last year. Mitigating,”  “Someone’s got a big, new cannon. Start of ugly things to come,” Cloudflare CEO Matthew Price said in a tweet.

400Gbps is a significant amount of traffic for a Distributed Denial of Service attack, it is a volume greater than the one observed in the  Spamhaus DDoS attack estimated at 300Gbps.

Attackers exploited weaknesses in the Network Time Protocol (NTP), it is a networking protocol widely used  for the clock synchronization purpose between systems over packet-switched, variable-latency data networks.

” NTP might become a vector for DDoS attacks because, like DNS, it is a simple UDP-based protocol that can be persuaded to return a large reply to a small request. Unfortunately, that prediction has come true.” reported the official post.

Recently, The US-CERT issued an Alert (TA14-017A) for

UDP-based Amplification Attacks listing the UDP protocols identified as potential attack vectors for this category of  Distributed Denial of Service attack.

  • DNS
  • NTP
  • SNMPv2
  • NetBIOS
  • SSDP
  • CharGEN
  • QOTD
  • BitTorrent
  • Kad
  • Quake Network Protocol
  • Steam Protocol
The number of NTP reflection attacks is increasing, numerous attacks have recently caused serious problems to some gaming web sites and service providers. In the following table are proposed all the protocols and related amplification factor, the one associated to NTP is scaring.
Exactly as DNS Reflection attack, in the Network Time Protocol (NTP) reflection Distributed Denial of Service the hackers sends a small spoofed 8-byte UDP packets to the vulnerable NTP server that requests megabytes of data to be sent to the target IP Address.

CVE has already coded the Network Time Protocol vulnerability as CVE-2013-5211, the attackers exploit the monlist command for the offensives.

As all versions of ntpd prior to 4.2.7 are vulnerable by default, to protect Network Time Protocol server it is necessary to update it to NTP 4.2.7, a version that has excluded the support of ‘monlist’ query substituted by a new safe ‘mrunlist’ function which uses a nonce value ensuring that received IP address match the actual requester.

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Pierluigi Paganini

(Security Affairs –  Distributed Denial of Service, cybercrime, NTP attack)

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