Snort mailing list archives
Re: UDP 1434 - worm spoofing or not?
From: "Gianluca Marcari" <gmarcari () tiscalinet it>
Date: Sat, 25 Jan 2003 21:50:32 +0100
From: "Glenn Forbes Fleming Larratt" <glratt () rice edu>
Hold on a second here. According to the specification for DHCP (I think - can anyone quote chapter and verse, and/or RFC?), 169.254.0.0/16 is reserved for DHCP clients that don't get a lease.
I agree. That's APIPA (Automatic Private IP Addressing) kicking in: it gives you an address in that range when it is configured for DHCP but cannot find a DHCP server.
Is it possible that this is not deliberate spoofing per se, but a DHCP-enabled infected machine that someone plugged into your non-DHCP network? Since the traffic is UDP, it wouldn't necessarily matter that it's spoofed for the purposes of worm propagation.
I would agree except for one single thing: if the client didn't find a DHCP server, and had to revert to APIPA, how did it find the router's address, to send packets out onto the 'net? :-)
Has everybody got their egress filtering working ? :)
I didn't even try to touch the Snort rulebase - just added a quick'n dirty "deny udp any any eq 1434" on my border router's ACL
Glenn Forbes Fleming Larratt Rice University Network Management glratt () rice edu
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Current thread:
- UDP 1434 jai (Jan 25)
- Re: UDP 1434 -=Quequero=- (Jan 25)
- Message not available
- Re: UDP 1434 jai (Jan 25)
- Re: UDP 1434 - worm spoofing or not? Glenn Forbes Fleming Larratt (Jan 25)
- Re: UDP 1434 - worm spoofing or not? Gianluca Marcari (Jan 25)
- Re: UDP 1434 - worm spoofing or not? kris carlier (Jan 27)
- Re: UDP 1434 jai (Jan 25)
- <Possible follow-ups>
- RE: UDP 1434 Steven Rudolph (Jan 25)
- Fw: UDP 1434 jai (Jan 25)
- RE: UDP 1434 Counselman, Chris Contractor/Sverdrup (Jan 27)