Security Basics mailing list archives
RE: Why bandwidth consuming ddos attack using only udp or icmp?
From: "Ajay Tikoo" <ajay () printwire org>
Date: Fri, 7 Mar 2008 13:37:01 -0500
Though, technically, you can include data in a SYN packet, please note the following: 1. There is a limit on the size of each TCP packet (assume 1500 Bytes). 2. If you send 3000 such packets, the bandwidth consumed = 3000 x 1500 = 4.5 MB. 3. You would not consider sending 4.5 MB to a server a bandwidth attack. 4. If common-sense prevails, there will be too many half-open connections before the step 2 above is completed. I hope that answers your question. Ajay Tikoo -----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of MontyRee Sent: Saturday, March 01, 2008 7:47 PM To: security-basics () securityfocus com; brian.bevers () gmail com; ajay () printwire org Subject: RE: Why bandwidth consuming ddos attack using only udp or icmp? Thanks again for your answer. I know already the difference of tcp and other stateless protocol. What I would like to know is that some data included spoofed tcp packets without 3 way handshake is possible or not? Is it impossible? Regards.
Sending huge data on TCP would require the TCP handshake be completed first. If the connection was initiated using a spoofed source IP, then how would the handshake complete. If real IP is used in order to complete the handshake, then the source identity (IP) is revealed.
Ajay Tikoo
? ? ? Mobile : Email??: Web???: http://www.sd.zain.com/ -------------------------------------------------------------------------- ? From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of MontyRee Sent: Saturday, March 01, 2008 9:15 AM To: gillettdavid () fhda edu; security-basics () securityfocus com Subject: RE: Why bandwidth consuming ddos attack using only udp or icmp? Thanks for your answer. Sorry for my poor english. what I would like to know is why ddos attacker don't using tcp for bandwidth consuming attack? for example, attacker can create some data included spoofed tcp packet, so he can send lots of tcp packets toward to the port 80/tcp of the victim like syn flooding attack. but I didn't see any ddos traffic like this. If I'm a attacker, this attack(data included spoofed tcp packet) would be more effective than udp or icmp, because this protocol can be filtered at the router by the policy. and syn flooding can be filtered by the syncookies, I think. and data included tcp packet toward to port 80 can't be filtered by the router, right? Thanks for your help.
From: gillettdavid () fhda edu To: chulmin2 () hotmail com; security-basics () securityfocus com Subject: RE: Why bandwidth consuming ddos attack using only udp or icmp? Date: Fri, 29 Feb 2008 08:51:25 -0800So, some network administrator said that he filtered all udp and icmp just against the bandwidth consuming ddos attack at the border router. (Surely some problems would be happen..dns..somethinf like that)Presumably he made an exception for DNS, and perhaps NTP. Note that the bandwidth bottleneck is typically outside the border router, so filters on that router only apply after the bandwidth has been consumed....Is it impossible or ineffective using tcp for bandwidth consuming attack in the point of attacker? anyone who saw the bandwidth consuming attack using tcp?It's not impossible, but it's extra work, and reveals the attacker's IP address to anyone who detects the attack. (Or at least one or more addresses under the attacker's control.) In your case, the TCP portion of the attack is probably trying to exhaust half-open connection entries (SYN flood) rather than bandwidth. He can use spoofed source addresses for that. David Gillett-----Original Message----- From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of MontyRee Sent: Thursday, February 28, 2008 6:52 PM To: security-basics () securityfocus com Subject: Why bandwidth consuming ddos attack using only udp or icmp? Hello, list. I have operated network in my company and recently I have experienced some ddos attack(inbound) on my network. It seems that the ddos attack was divided in two first, the bandwidth consuming attack was all consist of udp or icmp using big size packet(about 1500 byte). second tcp based attack for example http(80/tcp) is mostly creates lots of pps using small size packet(about 40 byte ) So, some network administrator said that he filtered all udp and icmp just against the bandwidth consuming ddos attack at the border router. (Surely some problems would be happen..dns..somethinf like that) and I have one question. Is it impossible or ineffective using tcp for bandwidth consuming attack in the point of attacker? anyone who saw the bandwidth consuming attack using tcp? Thanks in advance. _________________________________________________________________
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Current thread:
- RE: Why bandwidth consuming ddos attack using only udp or icmp? Scott (Mar 01)
- RE: Why bandwidth consuming ddos attack using only udp or icmp? MontyRee (Mar 03)
- Re: Why bandwidth consuming ddos attack using only udp or icmp? Amol Sapkal (Mar 04)
- RE: Why bandwidth consuming ddos attack using only udp or icmp? Murda Mcloud (Mar 04)
- RE: Why bandwidth consuming ddos attack using only udp or icmp? Ajay Tikoo (Mar 07)
- Re: Why bandwidth consuming ddos attack using only udp or icmp? pinowudi (Mar 10)
- <Possible follow-ups>
- RE: Why bandwidth consuming ddos attack using only udp or icmp? MontyRee (Mar 01)
- RE: Why bandwidth consuming ddos attack using only udp or icmp? Ajay Tikoo (Mar 01)
- Re: Why bandwidth consuming ddos attack using only udp or icmp? Brian Bevers (Mar 01)
- RE: Why bandwidth consuming ddos attack using only udp or icmp? MontyRee (Mar 03)