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Very peculiar Telnet probing (possibly spoofed?)
I have been rather reluctant to post this as I had hoped it was just a fluke. But this has been going on for nearly two weeks. We are getting banged by telnet probes from SE Asian sites... over 1000 different ones in all attacking the same address range. I suspect but cannot prove that the packets are being spoofed as we are dropping (not resetting) the probes, yet they continue. There are repeated probes from the same IP address for about 15-20 minutes or more, then it moves along, but the resulting router logs blocking them looks initially random (from SE Asia sites). Is someone out there to make a bad statement for APNIC by spoofing the origins, or is this some co-ordinated attack/probe.
The high-order octed of the attackers is consistently within one of these /8 netblocks (though not evenly spread, and cluster around certain address blocks as shown). I haven't heard of anything like this (other than recent SSH brute force, but this is telnet).
I'm getting attacks from:
159.226.x.x 202.x.x.x 203.x.x.x 210.x.x.x 211.x.x.x 218.x.x.x 219.x.x.x 220.x.x.x 221.x.x.x 222.x.x.x 61.x.x.x
Again, thousands of probes, about 10-20/sec when they're on a roll. These are attacks on a /18 subnet with only a small subnet (our secured servers) that is in danger (we block/drop telnet inbound to dynamic NAT but accept for static server translations)..
It is almost as if someone were spoofing the asian addresses to 'simulate' an Asian attack, but what with the big bot-nets, I suppose that's a possibility too, but all these addresses (that I looked at) were SE Asian in origin.
After passing the 1000 scanner benchmarkk today, with some manual aggregation of obvious problem areas, it still continues.
Anyone else seeing this? We're getting this more often than the SSHD scans.
Jeff Kell Systems/Network Security