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.
“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.
Pierluigi Paganini
February 12, 2014
