Security Incidents mailing list archives
RE: Strange attack question - seems udp
From: "Joshua Berry" <JBerry () PENSON COM>
Date: Mon, 17 Oct 2005 09:30:37 -0500
You don't see any ports because these are packet fragments (hence the "offset <number>"). This looks like some sort of malicious traffic because the offset of each sequential packet is wrong, the next offset is starting before the last one ended. These overlapping values are an older type of attack called a Teardrop attack. -----Original Message----- From: Mihai Tanasescu [mailto:mihai () duras ro] Sent: Thursday, October 13, 2005 1:09 PM To: incidents () securityfocus com Subject: Strange attack question - seems udp Hello, I've been getting things like these recently: 21:00:52.941148 IP (tos 0x0, ttl 127, id 28639, offset 11840, flags [+], length: 1500) 86.104.102.16 > 70.84.247.164: udp 21:00:52.941271 IP (tos 0x0, ttl 127, id 28639, offset 13320, flags [+], length: 1500) 86.104.102.16 > 70.84.247.164: udp 21:00:52.941394 IP (tos 0x0, ttl 127, id 28639, offset 14800, flags [+], length: 1500) 86.104.102.16 > 70.84.247.164: udp 21:00:52.941517 IP (tos 0x0, ttl 127, id 28639, offset 16280, flags [+], length: 1500) 86.104.102.16 > 70.84.247.164: udp 21:00:52.941640 IP (tos 0x0, ttl 127, id 28639, offset 17760, flags [+], length: 1500) 86.104.102.16 > 70.84.247.164: udp I have 24 subnets inside a Cisco 3750. After receiving many packets like these on 3-4 interfaces, Cisco starts loosing packets and acts abnormal. I have gathered the output show above from a Linux machine with tcpdump which acts as a border router. What I find strange is that there is no port specified (src,dst) and that the length of the packets is always 1500. Is there any way to filter something like this on the Cisco switch ? Is it caused by a virus or by a human ? (I have seen it from 3-4 different interfaces at a time and with 4-6 different destination IPs) Any help will be greatly appreciated. Sorry if I have posted this to the wrong list.
Current thread:
- Strange attack question - seems udp Mihai Tanasescu (Oct 17)
- Re: Strange attack question - seems udp Carles Fragoso i Mariscal (Oct 17)
- Re: Strange attack question - seems udp Mihai Tanasescu (Oct 19)
- Re: Strange attack question - seems udp Christoph Gruber (Oct 24)
- Re: Strange attack question - seems udp Mihai Tanasescu (Oct 19)
- RE: Strange attack question - seems udp David Gillett (Oct 17)
- Re: Strange attack question - seems udp Mihai Tanasescu (Oct 19)
- <Possible follow-ups>
- RE: Strange attack question - seems udp Joshua Berry (Oct 17)
- Re: Strange attack question - seems udp Dick St.Peters (Oct 19)
- Re: Strange attack question - seems udp Carles Fragoso i Mariscal (Oct 17)