Snort mailing list archives

Re: "portscans" that only hit one host, one time?


From: "Vinay A. Mahadik" <VAMahadik () lbl gov>
Date: Fri, 09 Aug 2002 10:52:14 -0700

Yes, that's a sNOACK scan (it hasn't got a ACK flag set, and is not a
series of other normal/scan types). Check the function 'CheckTCPFlags()'
towards its end in spp_portscan.c. The flag combination is definitely
weird and qualifies as a 'stealth' scan (stealth scans are not rate
based, but per packet).

Thanks,
Vinay

"McCammon, Keith" wrote:

[WARNING: Slightly off-topic]

Aug  9 11:48:39 204.210.241.146:2051 -> xxx.yyy.zzz.66:443
NOACK *2U*PRS*

I don't know much about spp_portscan internals, so I'm not sure why this was logged.  However, I'd sure as hell 
qualify this as a portscan.  This packet is definitely crafted to bypass a filter or elicit a response for 
fingerprinting or the like.

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--
Vinay A. Mahadik
Summer Intern
Computer Protection Program
Lawrence Berkeley National Laboratory
(510) 495 2618


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