A UDP flood attack is a volumetric
denial-of-service (DoS) attack using the
User Datagram Protocol
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in Network packet, packets) to other hosts on an Internet Protoco ...
(UDP), a sessionless/connectionless computer networking
protocol.
Using UDP for denial-of-service attacks is not as straightforward as with the
Transmission Control Protocol
The Transmission Control Protocol (TCP) is one of the main communications protocol, protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, th ...
(TCP). However, a UDP flood attack can be initiated by sending a large number of UDP
packets to random
ports Ports collections (or ports trees, or just ports) are the sets of makefiles and Patch (Unix), patches provided by the BSD-based operating systems, FreeBSD, NetBSD, and OpenBSD, as a simple method of installing software or creating binary packages. T ...
on a remote host. As a result, the distant host will:
* Check for the application listening at that port;
* See that no application listens at that port;
* Reply with an
ICMP Destination Unreachable packet.
Thus, for a large number of UDP packets, the victimized system will be forced into sending many ICMP packets, eventually leading it to be unreachable by other clients. The attacker(s) may also
spoof the
IP address
An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface i ...
of the UDP packets, ensuring that the excessive ICMP return packets do not reach them, and anonymizing their network location(s). Most operating systems mitigate this part of the attack by limiting the rate at which ICMP responses are sent.
UDP Flood Attack Tools:
*
Low Orbit Ion Cannon
Low Orbit Ion Cannon (LOIC) is an open-source network stress testing and denial-of-service attack application written in C#. LOIC was initially developed by Praetox Technologies, however it was later released into the public domain and is cur ...
*UDP Unicorn
This attack can be managed by deploying
firewalls at key points in a network to filter out unwanted network traffic. The potential victim never receives and never responds to the malicious UDP packets because the firewall stops them. However, as firewalls are 'stateful' i.e. can only hold a number of sessions, firewalls can also be susceptible to flood attacks.
There are ways to protect a system against UDP flood attacks. Here are examples of some of the possible measures:
* ICMP rate-limiting: This limitation is generally placed on ICMP responses at operating system level.
* Firewall-level filtering on the server: This enables suspicious packets to be rejected. However, it is possible for the firewall to collapse under the strain of a UDP flood attack.
* Filtering UDP packets (except for DNS) at network level: DNS requests are typically made using UDP. Any other source generating huge amounts of UDP traffic is considered suspicious, which leads to the packets in question being rejected.
References
External links
*{{cite web , title=CA-1996-01: UDP Port Denial-of-Service Attack , url=https://resources.sei.cmu.edu/asset_files/WhitePaper/1996_019_001_496172.pdf#page=5 , website=Carnegie Mellon University Software Engineering Institute , archive-url=https://web.archive.org/web/20010124064800/http://www.cert.org/advisories/CA-1996-01.html , archive-date=2001-01-24 , access-date=14 September 2019 , url-status=live
Denial-of-service attacks