Syn flood to TCP port 21 from priveleged port (80)
Hello, A couple of cuts from tcpdump output: 21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks. -- wbr, Oleg. "Anarchy is about taking complete responsibility for yourself." Alan Moore.
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage. I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router. All from multiple sequential registered /24s in whois, but all from one management company: 141.138.128.0/21 and 95.131.184.0/21 role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR AS49061 course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS. /kc On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said:
Hello,
A couple of cuts from tcpdump output:
21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0
Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks.
--?? wbr, Oleg.
"Anarchy is about taking complete responsibility for yourself." ?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead. Since your port 21 is open telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'. Your address was probably scanned and saw it could be used in the attack. Regards -- Donovan Van Dyk SOC Network Engineer Office: +1.954.620.6002 x911 Fort Lauderdale, FL USA The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such person), you are strictly prohibited from copying, disseminating or distributing this communication. If you have received this communication in error, please notify the sender immediately and destroy all electronic, paper or other versions. On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote: seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage. I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router. All from multiple sequential registered /24s in whois, but all from one management company: 141.138.128.0/21 and 95.131.184.0/21 role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR AS49061 course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS. /kc On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this traffic >on at least two completely independent ISPs near Moscow. The >rate is about a few dozen PPS hitting all BGP-announced networks. > >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for yourself." >?? ?? ?? Alan Moore. -- Ken Chase - math@sizone.org Guelph Canada
Not sure why reflected RSTs are the goal here, they're not much of an amplification to the original syn size. Additionally causing a mild dos of my clients' stuff when it begins throttling # of connections, ie noticeable. (not that i want to help scriptkids improve their attacks...). Im guessing port 80 was chosen for improved fw piercing. Sure is widespread though, 5 clients on very different networks all seeing similar saturation. Someone has a nice complete prescanned list of open ftps for the entire internet out there (or are they just saturating the whole /0?) Easy to filter though: tcp and src port 80 and src net '(141.138.128.0/21 or 95.131.184.0/21)' and dst port 21 Adapt for your fw rules of choice. /kc On Tue, Nov 01, 2016 at 07:39:40PM +0000, Van Dyk, Donovan said:
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead.
Since your port 21 is open
telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'.
Your address was probably scanned and saw it could be used in the attack.
Regards -- Donovan Van Dyk
SOC Network Engineer
Office: +1.954.620.6002 x911
Fort Lauderdale, FL USA
The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such person), you are strictly prohibited from copying, disseminating or distributing this communication. If you have received this communication in error, please notify the sender immediately and destroy all electronic, paper or other versions.
On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote:
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this traffic >on at least two completely independent ISPs near Moscow. The >rate is about a few dozen PPS hitting all BGP-announced networks. > >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for yourself." >?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
Yeah it is an odd ball attack for sure, here is a 5000 packet sample of what I was seeing in connection to this attack https://mystagic.io/80to21.pcap , don't think it's the entire /0 for ftp port as I am not seeing it on many other subnets, which is why I am thinking someone did a pre-scan before conducting this wacky attack, otherwise, I would have likely seen other port 21's seeing activity, but so far any IP that didn't have 21 as an actual service isn't seeing the syn packets. This could be unique to my location, others observing this attack may be able to chime in and report what they are seeing if they seen 80 src syn to port 21 where 21 isn't an actual ftp running. Yeah this is pretty easy to filter. On 1 November 2016 at 13:48, Ken Chase <math@sizone.org> wrote:
Not sure why reflected RSTs are the goal here, they're not much of an amplification to the original syn size. Additionally causing a mild dos of my clients' stuff when it begins throttling # of connections, ie noticeable. (not that i want to help scriptkids improve their attacks...). Im guessing port 80 was chosen for improved fw piercing.
Sure is widespread though, 5 clients on very different networks all seeing similar saturation. Someone has a nice complete prescanned list of open ftps for the entire internet out there (or are they just saturating the whole /0?)
Easy to filter though:
tcp and src port 80 and src net '(141.138.128.0/21 or 95.131.184.0/21)' and dst port 21
Adapt for your fw rules of choice.
/kc
On Tue, Nov 01, 2016 at 07:39:40PM +0000, Van Dyk, Donovan said:
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead.
Since your port 21 is open
telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'.
Your address was probably scanned and saw it could be used in the attack.
Regards -- Donovan Van Dyk
SOC Network Engineer
Office: +1.954.620.6002 x911
Fort Lauderdale, FL USA
The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such person), you are strictly prohibited from copying, disseminating or distributing this communication. If you have received this communication in error, please notify the sender immediately and destroy all electronic, paper or other versions.
On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote:
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this traffic >on at least two completely independent ISPs near Moscow. The >rate is about a few dozen PPS hitting all BGP-announced networks. > >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for yourself." >?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
what's the density of open port 21s on the planet though? trying to estimate the traffic resulting against the two target /21s. Your dump only has 2 ip's in it though, on your /19 so not representative. My dump is 500 synacks returned in 14 seconds to 32 ips in a /22. This would give 128M ftp responders across the whole /0 (modulo actual space in use, etc, so call it 32M responders?). (It's also a short timespan for a dump as well.) Syn-ack seems to be a 58 byte packet (?ish). 32 * 10^6 * 500/14 * 58*8 / 10^9 = 530 Gbps even if im off by 4 in density of ftp sites on the internet despite my already reducing it by 4, we're talking ~100+ Gbps. /kc On Tue, Nov 01, 2016 at 03:59:49PM -0600, Selphie Keller said:
Yeah it is an odd ball attack for sure, here is a 5000 packet sample of what I was seeing in connection to this attack https://mystagic.io/80to21.pcap , don't think it's the entire /0 for ftp port as I am not seeing it on many other subnets, which is why I am thinking someone did a pre-scan before conducting this wacky attack, otherwise, I would have likely seen other port 21's seeing activity, but so far any IP that didn't have 21 as an actual service isn't seeing the syn packets. This could be unique to my location, others observing this attack may be able to chime in and report what they are seeing if they seen 80 src syn to port 21 where 21 isn't an actual ftp running. Yeah this is pretty easy to filter.
On 1 November 2016 at 13:48, Ken Chase <math@sizone.org> wrote:
Not sure why reflected RSTs are the goal here, they're not much of an amplification to the original syn size. Additionally causing a mild dos of my clients' stuff when it begins throttling # of connections, ie noticeable. (not that i want to help scriptkids improve their attacks...). Im guessing port 80 was chosen for improved fw piercing.
Sure is widespread though, 5 clients on very different networks all seeing similar saturation. Someone has a nice complete prescanned list of open ftps for the entire internet out there (or are they just saturating the whole /0?)
Easy to filter though:
tcp and src port 80 and src net '(141.138.128.0/21 or 95.131.184.0/21)' and dst port 21
Adapt for your fw rules of choice.
/kc
On Tue, Nov 01, 2016 at 07:39:40PM +0000, Van Dyk, Donovan said:
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead.
Since your port 21 is open
telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'.
Your address was probably scanned and saw it could be used in the attack.
Regards -- Donovan Van Dyk
SOC Network Engineer
Office: +1.954.620.6002 x911
Fort Lauderdale, FL USA
The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such person), you are strictly prohibited from copying, disseminating or distributing this communication. If you have received this communication in error, please notify the sender immediately and destroy all electronic, paper or other versions.
On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote:
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this traffic >on at least two completely independent ISPs near Moscow. The >rate is about a few dozen PPS hitting all BGP-announced networks. > >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for yourself." >?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
Most of those networks are served by Prolexic DDOS mitigation (AS 32787), and according to BGPlay have been for a while. (AS carrying untoward material, like a Tor exit node or onion router?) But a couple /24s in the 95.* block are AS14537 Mohawk Internet Tech. in Quebec Canada such as 95.131.188.0/24 - unintended target? (careful who you buy /24's from!) So the only target being affected would be Mohawk unless they're setup to handle it. /kc -- Ken Chase - math@sizone.org Guelph Canada
There is some nice research regarding systems "abusable" for reflection by tcp port and the amplification factor depending on the OS: http://www.christian-rossow.de/publications/tcpamplification-woot2014.pdf And in more detail: https://www.usenix.org/system/files/conference/usenixsecurity14/sec14-paper- kuhrer.pdf Best regards, Chris On Tue, Nov 1, 2016 at 11:21 PM, Ken Chase <math@sizone.org> wrote:
what's the density of open port 21s on the planet though? trying to estimate the traffic resulting against the two target /21s.
Your dump only has 2 ip's in it though, on your /19 so not representative.
My dump is 500 synacks returned in 14 seconds to 32 ips in a /22. This would give 128M ftp responders across the whole /0 (modulo actual space in use, etc, so call it 32M responders?). (It's also a short timespan for a dump as well.) Syn-ack seems to be a 58 byte packet (?ish).
32 * 10^6 * 500/14 * 58*8 / 10^9 = 530 Gbps
even if im off by 4 in density of ftp sites on the internet despite my already reducing it by 4, we're talking ~100+ Gbps.
/kc
Yeah it is an odd ball attack for sure, here is a 5000 packet sample of what I was seeing in connection to this attack https://mystagic.io/80to21.pcap , don't think it's the entire /0 for ftp port as I am not seeing it on many other subnets, which is why I am thinking someone did a pre-scan before conducting this wacky attack, otherwise, I would have likely seen other port 21's seeing activity, but so far any IP that didn't have 21 as an actual service isn't seeing the syn packets. This could be unique to my location, others observing this attack may be able to chime in and report what they are seeing if they seen 80 src syn to port 21 where 21 isn't an actual ftp running. Yeah this is pretty easy to filter.
On 1 November 2016 at 13:48, Ken Chase <math@sizone.org> wrote:
Not sure why reflected RSTs are the goal here, they're not much of an amplification to the original syn size. Additionally causing a mild dos of my clients' stuff when it begins throttling # of connections, ie noticeable. (not that i want to help scriptkids improve their attacks...). Im guessing port 80 was chosen for improved fw piercing.
Sure is widespread though, 5 clients on very different networks all seeing similar saturation. Someone has a nice complete prescanned list of open ftps for the entire internet out there (or are they just saturating the whole /0?)
Easy to filter though:
tcp and src port 80 and src net '(141.138.128.0/21 or 95.131.184.0/21 )' and dst port 21
Adapt for your fw rules of choice.
/kc
On Tue, Nov 01, 2016 at 07:39:40PM +0000, Van Dyk, Donovan said:
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead.
Since your port 21 is open
telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'.
Your address was probably scanned and saw it could be used in the attack.
Regards -- Donovan Van Dyk
SOC Network Engineer
Office: +1.954.620.6002 x911
Fort Lauderdale, FL USA
The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such
are strictly prohibited from copying, disseminating or distributing
communication. If you have received this communication in error,
notify the sender immediately and destroy all electronic, paper or other versions.
On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote:
seeing an awful lot of port 80 hitting port 21. (Why would
ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this
On Tue, Nov 01, 2016 at 03:59:49PM -0600, Selphie Keller said: person), you this please port 80 traffic
>on at least two completely independent ISPs near Moscow. The >rate is about a few dozen PPS hitting all BGP-announced
networks.
> >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for
yourself."
>?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
This might be a little late on this thread, however I just saw the following news item on twitter which seemed pertinent to this story: http://www.theregister.co.uk/2016/11/02/william_hill_ddos/ I guess they're a bookie who's under DDoS? Theodore Baschak - AS395089 - Hextet Systems https://ciscodude.net/ - https://hextet.systems/ http://mbix.ca/ On Wed, Nov 2, 2016 at 3:46 AM, Christian Kildau <lists@chrisk.de> wrote:
There is some nice research regarding systems "abusable" for reflection by tcp port and the amplification factor depending on the OS: http://www.christian-rossow.de/publications/tcpamplification-woot2014.pdf
And in more detail: https://www.usenix.org/system/files/conference/ usenixsecurity14/sec14-paper- kuhrer.pdf
Best regards, Chris
On Tue, Nov 1, 2016 at 11:21 PM, Ken Chase <math@sizone.org> wrote:
what's the density of open port 21s on the planet though? trying to estimate the traffic resulting against the two target /21s.
Your dump only has 2 ip's in it though, on your /19 so not representative.
My dump is 500 synacks returned in 14 seconds to 32 ips in a /22. This would give 128M ftp responders across the whole /0 (modulo actual space in use, etc, so call it 32M responders?). (It's also a short timespan for a dump as well.) Syn-ack seems to be a 58 byte packet (?ish).
32 * 10^6 * 500/14 * 58*8 / 10^9 = 530 Gbps
even if im off by 4 in density of ftp sites on the internet despite my already reducing it by 4, we're talking ~100+ Gbps.
/kc
Yeah it is an odd ball attack for sure, here is a 5000 packet sample of what I was seeing in connection to this attack https://mystagic.io/80to21.pcap , don't think it's the entire /0 for ftp port as I am not seeing it on many other subnets, which is why I am thinking someone did a pre-scan before conducting this wacky attack, otherwise, I would have likely seen other port 21's seeing activity, but so far any IP that didn't have 21 as an actual service isn't seeing the syn packets. This could be unique to my location, others observing this attack may be able to chime in and report what they are seeing if they seen 80 src syn to port 21 where 21 isn't an actual ftp running. Yeah this is
easy to filter.
On 1 November 2016 at 13:48, Ken Chase <math@sizone.org> wrote:
Not sure why reflected RSTs are the goal here, they're not much of an amplification to the original syn size. Additionally causing a mild dos of my clients' stuff when it begins throttling # of connections, ie noticeable. (not
want to help scriptkids improve their attacks...). Im guessing port 80 was chosen for improved fw piercing.
Sure is widespread though, 5 clients on very different networks all seeing similar saturation. Someone has a nice complete prescanned list of open ftps for the entire internet out there (or are they just saturating the whole /0?)
Easy to filter though:
tcp and src port 80 and src net '(141.138.128.0/21 or 95.131.184.0/21 )' and dst port 21
Adapt for your fw rules of choice.
/kc
On Tue, Nov 01, 2016 at 07:39:40PM +0000, Van Dyk, Donovan said:
I think Ken has nailed it. I think the source addresses are spoofed so you reflect the connection (tcp syn ack) to those source addresses. Get enough of those connections and the server is dead.
Since your port 21 is open
telnet 109.72.248.114 21 Trying 109.72.248.114... Connected to 109.72.248.114. Escape character is '^]'.
Your address was probably scanned and saw it could be used in the attack.
Regards -- Donovan Van Dyk
SOC Network Engineer
Office: +1.954.620.6002 x911
Fort Lauderdale, FL USA
The information contained in this electronic mail transmission and its attachments may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient (or an individual responsible for delivery of the message to such
are strictly prohibited from copying, disseminating or distributing
communication. If you have received this communication in error,
notify the sender immediately and destroy all electronic, paper or other versions.
On 11/1/16, 3:29 PM, "Ken Chase" <math@sizone.org> wrote:
seeing an awful lot of port 80 hitting port 21. (Why would
ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said: >Hello, > >A couple of cuts from tcpdump output: > >21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 >21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 >21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 >21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0 > >Does anyone seeing this right now (18:31 UTC)? I see this
On Tue, Nov 01, 2016 at 03:59:49PM -0600, Selphie Keller said: pretty that i person), you this please port 80 traffic
>on at least two completely independent ISPs near Moscow.
The
>rate is about a few dozen PPS hitting all BGP-announced
networks.
> >--?? >wbr, Oleg. > >"Anarchy is about taking complete responsibility for
yourself."
>?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
Ditto. Same sources; 141.138.128.0/21 and 95.131.184.0/21 (give or take). Out of 1000 packet sample taken at 12:45:46 PDT (19:45:46 UTC) at boundary, 502 unique sources to 10 destination hosts on our AS. Obligatory data should this be of use to anyone listening in. -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Ken Chase Sent: November-01-16 12:29 PM To: Oleg A. Arkhangelsky Cc: nanog@nanog.org Subject: Re: Syn flood to TCP port 21 from priveleged port (80) seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage. I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router. All from multiple sequential registered /24s in whois, but all from one management company: 141.138.128.0/21 and 95.131.184.0/21 role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR AS49061 course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS. /kc On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said:
Hello,
A couple of cuts from tcpdump output:
21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0
Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks.
--?? wbr, Oleg.
"Anarchy is about taking complete responsibility for yourself." ?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
Does the synflood have tcp option headers? I am seeing this same activity at our forward observation system, however it's not showing any tcp options like mss,sack,timestamps etc, was curious if others were seeing the same [root@oakridge-intercept(~)]> tcpdump -nn -i eth0 'tcp and (tcp[13] == 2)' tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes 13:09:32.772506 IP 95.131.190.214.80 > 67.220.207.169.21: Flags [S], seq 3599006989, win 8192, length 0 13:09:32.809446 IP 95.131.185.150.80 > 67.220.207.169.21: Flags [S], seq 2409909072, win 8192, length 0 13:09:33.306737 IP 141.138.133.161.80 > 67.220.207.169.21: Flags [S], seq 1006681302, win 8192, length 0 13:09:33.946427 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0 13:09:33.946469 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0 13:09:34.263905 IP 194.73.173.103.80 > 67.220.207.170.21: Flags [S], seq 3818041920, win 8192, length 0 13:09:34.415558 IP 194.73.173.243.80 > 67.220.207.169.21: Flags [S], seq 3584410928, win 8192, length 0 On 1 November 2016 at 13:52, Emille Blanc <emille@abccommunications.com> wrote:
Ditto. Same sources; 141.138.128.0/21 and 95.131.184.0/21 (give or take).
Out of 1000 packet sample taken at 12:45:46 PDT (19:45:46 UTC) at boundary, 502 unique sources to 10 destination hosts on our AS.
Obligatory data should this be of use to anyone listening in.
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Ken Chase Sent: November-01-16 12:29 PM To: Oleg A. Arkhangelsky Cc: nanog@nanog.org Subject: Re: Syn flood to TCP port 21 from priveleged port (80)
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said:
Hello,
A couple of cuts from tcpdump output:
21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0
Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks.
--?? wbr, Oleg.
"Anarchy is about taking complete responsibility for yourself." ?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
Does the synflood have tcp option headers?
Not seeing any here. From this morning. 12:45:46.180665 194.73.173.17.80 > 216.57.181.189.21: S [tcp sum ok] 1158156467:1158156467(0) win 8192 (DF) (ttl 60, id 18499, len 40) 12:45:46.180667 194.73.173.17.80 > 216.57.181.189.21: S [tcp sum ok] 1158156467:1158156467(0) win 8192 (DF) (ttl 60, id 18499, len 40) 12:45:46.284617 141.138.128.137.80 > 216.57.182.18.21: S [tcp sum ok] 2595766696:2595766696(0) win 8192 (DF) (ttl 69, id 6478, len 40) From: Selphie Keller [mailto:selphie.keller@gmail.com] Sent: November-01-16 1:13 PM To: Emille Blanc Cc: Ken Chase; Oleg A. Arkhangelsky; nanog@nanog.org Subject: Re: Syn flood to TCP port 21 from priveleged port (80) Does the synflood have tcp option headers? I am seeing this same activity at our forward observation system, however it's not showing any tcp options like mss,sack,timestamps etc, was curious if others were seeing the same [root@oakridge-intercept(~)]> tcpdump -nn -i eth0 'tcp and (tcp[13] == 2)' tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes 13:09:32.772506 IP 95.131.190.214.80 > 67.220.207.169.21: Flags [S], seq 3599006989, win 8192, length 0 13:09:32.809446 IP 95.131.185.150.80 > 67.220.207.169.21: Flags [S], seq 2409909072, win 8192, length 0 13:09:33.306737 IP 141.138.133.161.80 > 67.220.207.169.21: Flags [S], seq 1006681302, win 8192, length 0 13:09:33.946427 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0 13:09:33.946469 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0 13:09:34.263905 IP 194.73.173.103.80 > 67.220.207.170.21: Flags [S], seq 3818041920, win 8192, length 0 13:09:34.415558 IP 194.73.173.243.80 > 67.220.207.169.21: Flags [S], seq 3584410928, win 8192, length 0 On 1 November 2016 at 13:52, Emille Blanc <emille@abccommunications.com<mailto:emille@abccommunications.com>> wrote: Ditto. Same sources; 141.138.128.0/21<http://141.138.128.0/21> and 95.131.184.0/21<http://95.131.184.0/21> (give or take). Out of 1000 packet sample taken at 12:45:46 PDT (19:45:46 UTC) at boundary, 502 unique sources to 10 destination hosts on our AS. Obligatory data should this be of use to anyone listening in. -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org<mailto:nanog-bounces@nanog.org>] On Behalf Of Ken Chase Sent: November-01-16 12:29 PM To: Oleg A. Arkhangelsky Cc: nanog@nanog.org<mailto:nanog@nanog.org> Subject: Re: Syn flood to TCP port 21 from priveleged port (80) seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage. I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router. All from multiple sequential registered /24s in whois, but all from one management company: 141.138.128.0/21<http://141.138.128.0/21> and 95.131.184.0/21<http://95.131.184.0/21> role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk<mailto:networkservices@williamhill.co.uk> address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR AS49061 course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS. /kc On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said:
Hello,
A couple of cuts from tcpdump output:
21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0
Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks.
--?? wbr, Oleg.
"Anarchy is about taking complete responsibility for yourself." ?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org<mailto:math@sizone.org> Guelph Canada
yeah it looks like the person behind the flood may have scanned for active ftp servers, not seeing any activity on other observation subnets of this flood, and so far the only servers showing this port 80 to port 21 is ones that do have actual ftp servers, however, the connection is not actually establishing it's only showing SYN incoming and a SYN-ACK outgoing and never gets a completed 3way handshake, so it could be a very odd reflected syn-ack flood against possible web servers origin ip addresses. On 1 November 2016 at 14:28, Emille Blanc <emille@abccommunications.com> wrote:
Does the synflood have tcp option headers?
Not seeing any here. From this morning.
12:45:46.180665 194.73.173.17.80 > 216.57.181.189.21: S [tcp sum ok] 1158156467:1158156467(0) win 8192 (DF) (ttl 60, id 18499, len 40)
12:45:46.180667 194.73.173.17.80 > 216.57.181.189.21: S [tcp sum ok] 1158156467:1158156467(0) win 8192 (DF) (ttl 60, id 18499, len 40)
12:45:46.284617 141.138.128.137.80 > 216.57.182.18.21: S [tcp sum ok] 2595766696:2595766696(0) win 8192 (DF) (ttl 69, id 6478, len 40)
*From:* Selphie Keller [mailto:selphie.keller@gmail.com] *Sent:* November-01-16 1:13 PM *To:* Emille Blanc *Cc:* Ken Chase; Oleg A. Arkhangelsky; nanog@nanog.org
*Subject:* Re: Syn flood to TCP port 21 from priveleged port (80)
Does the synflood have tcp option headers?
I am seeing this same activity at our forward observation system, however it's not showing any tcp options like mss,sack,timestamps etc, was curious if others were seeing the same
[root@oakridge-intercept(~)]> tcpdump -nn -i eth0 'tcp and (tcp[13] == 2)'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
13:09:32.772506 IP 95.131.190.214.80 > 67.220.207.169.21: Flags [S], seq 3599006989, win 8192, length 0
13:09:32.809446 IP 95.131.185.150.80 > 67.220.207.169.21: Flags [S], seq 2409909072, win 8192, length 0
13:09:33.306737 IP 141.138.133.161.80 > 67.220.207.169.21: Flags [S], seq 1006681302, win 8192, length 0
13:09:33.946427 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0
13:09:33.946469 IP 141.138.134.193.80 > 67.220.207.170.21: Flags [S], seq 3627295948, win 8192, length 0
13:09:34.263905 IP 194.73.173.103.80 > 67.220.207.170.21: Flags [S], seq 3818041920, win 8192, length 0
13:09:34.415558 IP 194.73.173.243.80 > 67.220.207.169.21: Flags [S], seq 3584410928, win 8192, length 0
On 1 November 2016 at 13:52, Emille Blanc <emille@abccommunications.com> wrote:
Ditto. Same sources; 141.138.128.0/21 and 95.131.184.0/21 (give or take).
Out of 1000 packet sample taken at 12:45:46 PDT (19:45:46 UTC) at boundary, 502 unique sources to 10 destination hosts on our AS.
Obligatory data should this be of use to anyone listening in.
-----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Ken Chase Sent: November-01-16 12:29 PM To: Oleg A. Arkhangelsky Cc: nanog@nanog.org Subject: Re: Syn flood to TCP port 21 from priveleged port (80)
seeing an awful lot of port 80 hitting port 21. (Why would port 80 ever be used as source?). Also saw a buncha cpanel "FAILED: FTP" alerts flickering on and off as the service throttled itself at a couple client sites I manage.
I see 540 unique source IPs hitting 32 destinations on my network in just 1000 packets dumped on one router.
All from multiple sequential registered /24s in whois, but all from one management company:
141.138.128.0/21 and 95.131.184.0/21
role: William Hill Network Services abuse-mailbox: networkservices@williamhill.co.uk address: Infrastructure Services 2 City Walk Sweet Street Leeds LS11 9AR
AS49061
course, synfloods can be spoofed... perhaps they're hoping for a retaliation against WHNS.
/kc
On Tue, Nov 01, 2016 at 09:44:23PM +0300, Oleg A. Arkhangelsky said:
Hello,
A couple of cuts from tcpdump output:
21:31:54.995170 IP 141.138.131.115.80 > 109.72.248.114.21: Flags [S], seq 1376379765, win 8192, length 0 21:31:55.231925 IP 194.73.173.154.80 > 109.72.241.198.21: Flags [S], seq 2254756684, win 8192, length 0 21:27:50.413927 IP 95.131.188.179.80 > 109.72.248.114.21: Flags [S], seq 3619475318, win 8192, length 0 21:27:50.477014 IP 95.131.191.77.80 > 109.72.248.114.21: Flags [S], seq 2412690982, win 8192, length 0
Does anyone seeing this right now (18:31 UTC)? I see this traffic on at least two completely independent ISPs near Moscow. The rate is about a few dozen PPS hitting all BGP-announced networks.
--?? wbr, Oleg.
"Anarchy is about taking complete responsibility for yourself." ?? ?? ?? Alan Moore.
-- Ken Chase - math@sizone.org Guelph Canada
participants (7)
-
Christian Kildau -
Emille Blanc -
Ken Chase -
Oleg A. Arkhangelsky -
Selphie Keller -
Theodore Baschak -
Van Dyk, Donovan