We got hit with this in September. UDP/19 became our most busiest port overnight. Most of the systems participating were printers. We dropped it at the border, and had no complaints or ill effects. —-Vlad Grigorescu Carnegie Mellon University On Jun 11, 2013, at 11:39 AM, Bernhard Schmidt <berni@birkenwald.de> wrote:
Heya everyone,
we have been getting reports lately about unsecured UDP chargen servers in our network being abused for reflection attacks with spoofed sources
http://en.wikipedia.org/wiki/Character_Generator_Protocol
| In the UDP implementation of the protocol, the server sends a UDP | datagram containing a random number (between 0 and 512) of characters | every time it receives a datagram from the connecting host. Any data | received by the server is discarded.
We are seeing up to 1500 bytes of response though.
This seems to be something new. There aren't a lot of systems in our network responding to chargen, but those that do have a 15x amplification factor and generate more traffic than we have seen with abused open resolvers.
Anyone else seeing that? Anyone who can think of a legitimate use of chargen/udp these days? Fortunately I can't, so we're going to drop 19/udp at the border within the next hours.
Regards, Bernhard