Weird traffic

[julio sanchez <pete.sanches () gmail com>]

Hi,

We're experiencing some weird arp traffic on our network, some box scan
constantly the subnets with loop "who-has" request
All the box are all windows vista sp1 fully patched.
We did format all the  supect box, and isolate them on a vlan, to reinstall
vista, updates, kaspersky, then we put it back on the network, and still
some ramdom freshly formated box scanning the network.
We find out that Vista will do an arp scan when it search for a network
printer, but it does this once.
The problem we have is an almost permanent arp scan on various boxs.
We know that some worm was hitting some network around the world with the
smb vulnerability, but all of our boxs are fully updated.
Have you experienced something like this before, or it seems to be legit
traffic ?
Can this be a worm or something related ?

Thanks in advance

Pete

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