Syn flood DOS (6009)

The signature for syn flood DOS (6009) has two values that I can see will alter the signature threshold.
event-counter
event-count: 2600 default: 200
event-count-key: AxBx <defaulted>
specify-alert-interval
yes
alert-interval: 2 default: 2
The definition for the signature is that it will detect a flood of TCP SYN packets at a rate of 100 per second or greater. We have tried to adjust the signature that this value is higher and no matter what the event count is, it continues to trigger in our environment. At 1300 syns per/sec, (event-count: 2600) an alert is still received for http proxy servers.
Have I over looked the parameter that needs to be adjusted in order to increase the threshold of this signature or is it just not tunable.

By default, flows with 200pkts/2sec above are alerted. You can change the threshold by CLI

Similar Messages

Sig SYN Flood DOS id="6009" dest address 0.0.0.0

Hi, All!
I receive sig 6009 with destination address 0.0.0.0:
evIdsAlert: eventId="1244180117471597849" severity="medium" vendor="Cisco"
originator:
hostId: IDS
appName: sensorApp
appInstanceId: 413
time: Jul 6 2009 14:18:14 EEST (1246879094502611000) offset="180" timeZone="UTC"
signature: created="20060220" type="anomaly" version="S214" description="SYN Flood DOS" id="6009"
subsigId: 0
sigDetails: SYN Flood DOS
marsCategory: DoS/Host
marsCategory: DoS/Network/TCP
interfaceGroup: vs0
vlan: 0
participants:
attacker:
addr: 192.168.155.72 locality="OUT"
port: 0
target:
addr: 0.0.0.0 locality="OUT"
port: 0
os: idSource="unknown" relevance="unknown" type="unknown"
summary: 3 final="true" initialAlert="1244180117471597835" summaryType="Regular"
alertDetails: Regular Summary: 3 events this interval ;
riskRatingValue: 63 targetValueRating="medium"
threatRatingValue: 63
interface: fe0_1
protocol: tcp
I cannot get at the meaning - address 0.0.0.0?
It`s bug?

No, it's not a bug. The scanning signatures summerize the attacked addresses into 0.0.0.0
This is because in scans there are a LOT of dezstination addresses that are hit inorder to fire the signature but there is only one attacked address field in ever signature.

Syn flood signature 6009/0 actions

Hi is there an option when this signature fires to block the attacker or this attack and not just log the attack? I tried to set the actions but the log says no action taken.

Hi Thx for the answer. I did add the action but no luck or does it nog log this action? The traffic hits the client inside the network so the ips does not block.
Event ID
1397033001306299442
Severity
high
Host ID
IPS-DEB1-1
Application Name
sensorApp
Event Time
01/06/2015 10:18:30
Sensor Local Time
01/06/2015 09:18:30
Signature ID
6009
Signature Sub-ID
0
Signature Name
SYN Flood DOS
Signature Version
S593
Signature Details
SYN Flood DOS
Interface Group
vs1
VLAN ID
0
Interface
te7_0
Attacker IP
xx.xx.xxx.84
Protocol
tcp
Attacker Port
1321
Attacker Locality
OUT
Target IP
yy.yy.yy.102
Target Port
80
Target Locality
OUT
Target OS
unknown unknown (relevant)
Actions
Risk Rating
TVR=medium ARR=relevant
Risk Rating Value
95
Threat Rating
95
Reputation
Context Data
Packet Data
Event Summary
0
Initial Alert
Summary Type
Final Alert
Event Status
New
Event Notes

SYN flood attack log In CSA MC

I got an SYN flood attack log in CSA MC
CSA log: TESTMODE: A potential SYN Flood attack has been detected. This may also indicate a possible routing problem. Reason: The TCP Listen Queue is full using interface Wired\HP NC7781 Gigabit Server Adapter #2. TCP: CSA MC IP/5401->local Instance IP/4418, flags 0x12. The operation would have been denied.
(Note: In log I have specified CSA MC IP and local Instance IP instead of its IP address)
I understood that SYN flooding is a type of denial of service attack and this alert has occured when a TCP/IP connection was requested by MC to the Instance. It has resulted in a half open connection, as the return address that is not in use. MC has detected it and it got denied.
Please let me know what action I have to take at tins point?
Thanks
Arumugam.K

Arumugam,
We've been having similar issue regarding SYN flood alerts. The affected system in turn starts to send additional ACK requests. This results in issues with the IIS functionality on that server. Clients begin to no longer have the ability to access the site hosted on the server. We've been battling between Cisco and Microsoft on this one. The issue appears to have started around Patch Tuesday in February.
My question to you is this: Have you noticed any latency with the system that is reporting the SYN flood? I'm curious if the problem is local to us, or possibly wide spread.

A SYN flood attack!

when i run
server$ dmesg command i got this message.
WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!

is the ip given a public ip and is the sun machine behind a firewall or running a firewall? most new deployed servers will not see enough traffic on segments behind firewalls to cause messages like this. ive run scanners that can cause messages like this or test clients that generate load as well...

Syn flood attack?

Hello,
I work in an organization in which there is an automatic monitoring of network connections. Yesterday I had a notification of a possible syn flood attack originated by my Mac targeting an IP address (and port: 8000) that I found out to be associated to an internet radio. I did some network monitoring and I found out that with iTunes closed there were no packets with that IP as destination address... has anyone experinced such a problem?
Sincerely
Giuseppe

Arumugam,
We've been having similar issue regarding SYN flood alerts. The affected system in turn starts to send additional ACK requests. This results in issues with the IIS functionality on that server. Clients begin to no longer have the ability to access the site hosted on the server. We've been battling between Cisco and Microsoft on this one. The issue appears to have started around Patch Tuesday in February.
My question to you is this: Have you noticed any latency with the system that is reporting the SYN flood? I'm curious if the problem is local to us, or possibly wide spread.

RV320 massive SYN Flooding attacks?

Hi
I have purchased a RV320 small business router for my home office, but i am experiencing massive SYN Flooding attacks when clients connect to my ftp and when rsync backup is performed.
My equipment consists of
Cisco RV320 Router running v1.1.0.09 (2013-07-04, 13:28:17) FW
Synology DS212 Nas
Setup
Cisco RV320 Router with static IP 192.168.1.1
WAN1 is used and configured with an static WAN IP
DHCP Range from 192.168.1.100 to 149
Port Range Forwarding Table
FTP[TCP/21~21] to IP 192.168.1.2
FTP Range[TCP/55536~55543] to IP 192.168.1.2
Rsync UDP[UDP/873~873] to IP 192.168.1.2
Synology DS212 Nas with static IP 192.168.1.2
Each time a user connects to my ftp server, I get a lot of these errors.
This is just a small sample of the log
[HACK] SynFlooding Attack
IN=eth1 OUT=eth0 SRC=xx.xxx.xx.xxx DST=192.168.1.2 DMAC=e0:2f:6d:75:34:d9 SMAC=00:13:72:52:16:5c LEN=52 TOS=0x00 PREC=0x00 TTL=120 ID=16112 DF PROTO=TCP SPT=45496 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
The same happens when an rsync backup is running on my DS212
2013-10-05, 12:11:15
[HACK] SynFlooding Attack
IN=eth1 OUT=eth0 SRC=xx.xxx.xxx.xx DST=192.168.1.2 DMAC=e0:2f:6d:75:34:d9 SMAC=00:13:72:52:16:5c LEN=60 TOS=0x00 PREC=0x00 TTL=54 ID=42649 DF PROTO=TCP SPT=36846 DPT=873 WINDOW=5840 RES=0x00 SYN URGP=0
If more information is needed please let me know
Any ideas why this happens?
Thanks
Martin

Maybe a stupid question, how do I create a support ticket?
If I click on the link "contact us" then I chose
Open a Technical Support Request here
But it require the following as you can read
Your login ID is not set up to access the TAC Service Request Tool (TSRT).
To obtain access, add all of your Cisco service contract numbers to your profile by going to the
Cisco Profile Manager - Request to Insert Contracts
. If you are a Cisco Partner or a customer with a Service Access Management Administrator, please contact that resource to obtain access to your service contracts. You may use the
Service Access Management Tool
to find your Service Access Management Administrator.
Unsure of your contract number? Your
Cisco Partner
, Reseller or Cisco Services representative can help provide a complete list of your service contracts.
The TAC Service Request Tool (TSRT) is designed to support contract-entitled services only at this time. For urgent issues or warranty service please contact the
Cisco Technical Assistance Center
via telephone.
See
Cisco Global Technical Services Quick Start Guide for additional assistance. Your login ID is not set up to access the TAC Service Request Tool (TSRT).
To obtain access, add all of your Cisco service contract numbers to your profile by going to the Cisco Profile Manager - Request to Insert Contracts. If you are a Cisco Partner or a customer with a Service Access Management Administrator, please contact that resource to obtain access to your service contracts. You may use the Service Access Management Tool to find your Service Access Management Administrator.
Unsure of your contract number? Your Cisco Partner, Reseller or Cisco Services representative can help provide a complete list of your service contracts.
The TAC Service Request Tool (TSRT) is designed to support contract-entitled services only at this time. For urgent issues or warranty service please contact the Cisco Technical Assistance Center via telephone.
See Cisco Global Technical Services Quick Start Guide for additional assistance.

Syn Flood :0(

We have a very large network at work and we have been having some internet timeout issues so we got some people in to monitor packets and perform a general network health check.
I got called up by the networking people saying that there has been a syn flood detected coming from my mac address on my macbook :0(
I know that mac’s are subject to network attacks but I thought that I have covered all my bases, I have Symantec installed and I keep up to date with my security updates etc.
Can anybody give me any pointers as to where to start to diagnose if there is an issue with my mac, I have used macscan and that found nothing I have also used little snitch to see if anything crops up asking for a network connect but nothing :0(
Any suggestions are greatly appreciated!

Sounds like something that should be posted to the Networking or Server Products forum.

Syn flood software?

i'm trying to test some syn flood mitigation techniques in my lab studies and i'm looking for a decent syn flood prog if anyone knows of one. tia.

If you check out the Sectools website (sectools.org) or if you download BackTrack (http://www.remote-exploit.org/backtrack_download.html) you can find a lot of really useful tools. Most of these are hacking tools so be sure to use them in accordance with whatever policies you are subject. I've used hPing in the past to simiulate syn floods and dDos attacks.
Good luck!

Possible SYN flooding on port 443. Sending cookies.

I have an older mobility server. 221 users. Version 1.2.4 build 966. Its on SLES 11 sp1. Also a bit dated. Early in the morning Saturday the server...

I have a working GroupWise Mobility service, but recently had to change
the SSL certificate, because the validity of the previous expired....

New Package: Arno's iptables firewall scripts

I made a PKGBUILD for Arno IPTABLES firewall script. This script has protected my home network for long time and I realized that some other Archers would also like to use it. Also, syslog-ng.conf example is included to get iptable logs into their own log file.
Script has clear, easy and well commented configuration file. Nice list of
Features
Very secure stateful filtering firewall
Both kernel 2.4 & 2.6 support
It can be used for both single- and multi(eg. dual)-homed boxes
Masquerading (NAT) and SNAT support
Multiple external (internet) interfaces
Support multiroute NAT & SNAT (load balancing over multiple (internet) interfaces)
Port forwarding (NAT)
Support MAC address filtering
Support for DSL/ADSL modems
Support for PPPoE, PPPoA and bridging modem setups
Support for static and ISP assigned (DHCP) IPs
Support for (transparent) proxies
Full support for DMZ's and DMZ-2-LAN forwarding. You can also use it to isolate your eg. wireless LAN.
(Nmap)(stealth) portscan detection
Protection against SYN-flooding (DoS attacks)
Protection against ICMP-flooding (DoS attacks)
Extensive user-definable logging with rate limiting to prevent log flooding
Includes options to optimize your throughput
User definable open ports, closed ports, trusted hosts, blocked hosts etc.
Log & protection options are both highly customizable
Support for custom iptables rules in a seperate file
It can be used with chkconfig runlevel system (eg. RedHat/Fedora)
Main focus on TCP/UDP/ICMP but additional support for *ALL* IP protocols
It works with Freeswan IPSEC (VPN) & SSH Sentinel (http://www.freeswan.org) (+virtual IP's)
It works with PoPTop PPTP (http://www.poptop.org)
It works with UPnP
DRDOS protection/detection (experimental)
It's easy to configure
And much more...
(edit) PKGBUILD is in the AUR.
This is my first package ever so tell me what to fix. I will put this to AUR if supported and this really works.

1c3d0g wrote:
Is this similar to QuickTables?
http://qtables.radom.org/
Arno's iptables has a config file that will be edited as needed and script reads the config file everytime it is executed.
I can put this pkgbuild to AUR. The init script is not Arch like. I decided to use Arno's script as is in /etc/rc.d/ because I want to see what happens. I could do a Arch type of init script that executes the firewall script arch way.
What do you think?

SG300-10P SYN Protection

Hi Community,
just registered after reading some topics in the last months. Great answers here - thank you for that!
No I have a minor issue with a new feature and did not find any solutions yet.
Yesterday I upgraded my SG300-10P to firmware 1.2.7.76. I was curious about the new SYN Protection feature, but it seems to do nothing on my installation.
The switch is running in Layer 2 mode. I have ACLs in place and DoS prevention is not enabled. I also tried clearing ACLs and enabling DoS prevention. As I understood the Admin Guide enabling DoS in the Security Suite Settings is not necessary for using the SYN Protection.
In my firewall I see about 300 pps with SYN flags only arriving. What "they" do is sending me SYN packest to port 80 from forged IPs, so that my system should send SYN-ACKs to the victim system. In this case it is the Arab Bank. They are down at the moment...I think that is called a spoofed SYN flood attack.
So I thougt the SYN Protection feature should exactly solve that problem but it does not and does not show any "Last Attack" entries.
If I put a SYN filter in place it works, even if I put SYN Rate Protection in place. But that is just a dirty workaround.
Did I miss something?
Maybe somebody has some hints for me!
Best wishes,
Alex
BTW: my firewall blocks those SYN packets with a SNORT rule, so I am no "helper" to those attacks and that is why the problem is minor to me.

Well, finally I discovered that I can provocate an attack with hping3 but only when I flood the switch interface address itself not other hosts on other switch ports. I can bring them down without any reaction from the switch.
So it seems, that the feature SYN Protection only protects the switch itself from SYN floods.
Not as useful as I thought.
Best wishes,
Alex

Generated some Dos attacks: no correponding IDS event is generated

I installed and configured a Cisco IDS 4250 sensor.
Actually the sniffing interface has been placed on a lan segment residing on the internal network, so, by monitoring IEV logs, I could see lots of events, but all belonging to a few category of signatures, and quite all informational. That's why, In order to generate some more significant network activity to verify correct sensor behaviour, I placed my workstation running a vulnerability assessment tool (ISS Internet Scanner) on the outside vlan (where the sniffing interface resides), and issued several common dos attacks against one workstation residing on one of the inside vlans.
Some example of attacks generated are : SYN flood, Ping of death, UDP bomb, Land, Teardrop. I also generated a lot of tcp scan activity. Using Internet Scanner logs I verified that those attacks reached the destination machine.
The fact is that neither IEV default view nor "sh ev" sensor commands showed any event related to my activity. The only events generated by my workstation during my tests, matched signatures "NET FLOOD UDP" (maybe signame 6910) and signature with sig number 1107 (I don't remember the name). In both cases destination ip is multicast or broadcast address.
I verified that those signatures I was expected to match my attack packets were enabled (I verified so by "sh conf" command), so I don't see any reason why the sensor did not register any event related to the attacks I perpetrated.
Am I missing something ? Have anyone any idea to make me understand why the results are not the ones expected?
Thanks in advance and Regards
Marina

When a user complains that they are only seeing alarms with multicast or broadcast addresses, then this usually points to a sensor connected to a switch where Span has not been configured.
When the sensor is connected to a switch, the switch will normally only send broadcast and multicast (with an occasional unicast) packet to the sensor.
So the sensor is not being sent the packets created by your ISS scanner.
The switch must be configured to copy these packets to your sensor. This switch configuration is normally done through the Span or Monitor command. Check your switch configuration to see how to configure these commands on your switch.
If you are not connecting the sensor to the switch or believe that the Span configuration is correct, then the next step is to run tcpdump on the sensor and verify whether or not the packets are actually being sent to the sensor.
1) In older versions of the sensor you need to configure the sensor to monitor the interface (I think was changed in version 4.1(4) so the interface can still be monitored while tcpdump is used)
2) Create a service account
3) Login to the service account
4) Switch to user root (using same password as service account).
5) Type "ifconfig -a" and determine which interface is your sniffing interface.
6) Run "tcpdump -i " to start seeing packets coming in that interface.
7) Execute the ISS scan.
8) Look through the output of tcpdump to see if those packets are making it to the sensor.
9) If the tcpdump does not see the ISS packets, then either span is misconfigured or the switch is not plugged in where you think it is.
10) If the tcpdump is seeing the packets, then reconfigure the sensor to watch the interface again.
If you have verified that the sensor IS receiving the packets then the next step is to try and generate traffic that triggers specific signatures.
A side note:
Often times scanners can tell you about a vulnerability without actually executing the attack. The scanner checks OS version and patches to see if it is vulnerable, but does not send packets to actually attack the machine. Especially in cases where sending the attack itself would have caused the target machine to crash.
This type of reconaissance is often considered benign and will not trigger the alarm. An actual attack has to be executed against the vulnerability to fire the alarm.
So for your ISS scanner you should see some alarms, but will not likely see alarms for every vulnerability that the ISS notifies you about.

Ping Flood - is this a security risk?

In my Administration Security log file I have entries I do not understand. Can anyone tell me what they might mean?
SYN Flood - this is appearing one to three times a week for the last two months.
LAN-side Ping Flood
IP packet w/MC or BC SRC addr - this appears about as often as Flood

I see this happening on my WRV200 Firmware Version: 1.0.32.2.
I run a tcpdump from linux and I see the router ping flooding the network. I have copy a small dump from what I see. The routers last restart was between 24 -> 48. The longer the router has been running the more ID start repeating.
12:15:03.994218 IP gateway > 192.168.2.255: ICMP echo request, id 876, seq 41597, length 64
12:15:04.551532 IP gateway > 192.168.2.255: ICMP echo request, id 841, seq 43492, length 64
12:15:05.031502 IP gateway > 192.168.2.255: ICMP echo request, id 876, seq 41598, length 64
12:15:05.575543 IP gateway > 192.168.2.255: ICMP echo request, id 841, seq 43493, length 64
12:15:06.053295 IP gateway > 192.168.2.255: ICMP echo request, id 876, seq 41599, length 64
12:15:06.606406 IP gateway > 192.168.2.255: ICMP echo request, id 841, seq 43494, length 64
12:15:07.071786 IP gateway > 192.168.2.255: ICMP echo request, id 876, seq 41600, length 64
12:15:07.639247 IP gateway > 192.168.2.255: ICMP echo request, id 841, seq 43495, length 64
12:15:08.127192 IP gateway > 192.168.2.255: ICMP echo request, id 876, seq 41601, length 64
Message Edited by theghost on 07-02-2007 09:20 AM

OMG, my first real Lion problem: **SYS Flood

I've run into my first Lion problem that I can't figure out, but maybe it's just a coincidence that it just started happening now, but I am getting these messages in my router security log:
08/15/2011 19:13:09 **SYN Flood** 192.168.2.2, 55636->> 17.149.34.231, 5223 (from WAN Outbound)
I am getting them from all devices hooked to the lan, i.e.. 2.2-2.x, and the IP listed is always mostly from an apple server! For example, in this case it's:
Not sure what to do, as I can't find a setting in the router to stop checking for that, and if happens enough times, it clogs the router and I loose Internet connectivity. I am not running any torrent programs, but like I said it's issued across all devices on the Lan (even my lowly iPhone). Any ideas? thx!
coocoo

I have turned off options in the modem so it is not logged anymore.
With further investigation I have found it occurs when the upload performance has dropped off. I seem to be get poor upload performance regularly, and I think there are dropped packets. If there is a dropped packet during the ack 3 way handshake, it would trigger a SYN Flood error.
I don't know why the upload performance drops off.
Perhaps someone on the same cable segment is running a file share server and taking all the bandwidth??

Syn flood DOS (6009)

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