Hmmm. Do you not run a default deny at your border, which would catch this sort of thing? Granted thats not always possible I suppose. Maybe block all UDP you dont specifically need? Do you have an ids/ips? If not, look at SecurityOnion on a SPAN port, it will provide great insight into whats happening.
Generally these sort of legacy services are only used for malicious activity and will light up an ids/ips like a Christmas tree. They must be old boxes. I cant think of any recent os distributions which would even have these services listening, let alone installed. Bernhard Schmidt <be...@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 -- Charles Wyble char...@knownelement.com / 818 280 7059 CTO Free Network Foundation (www.thefnf.org)
