LinuxQuestions.org
Review your favorite Linux distribution.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Security
User Name
Password
Linux - Security This forum is for all security related questions.
Questions, tips, system compromises, firewalls, etc. are all included here.

Notices


Reply
  Search this Thread
Old 10-24-2004, 08:17 PM   #1
qwijibow
LQ Guru
 
Registered: Apr 2003
Location: nottingham england
Distribution: Gentoo
Posts: 2,672

Rep: Reputation: 47
firewall detected outgoing sub7 connect attmept !!!???


Code:
IN= OUT=eth0 SRC=MY_IP DST=OTHER_IP LEN=44 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=TCP SPT=1214 DPT=1234 WINDOW=5840 RES=0x00 ACK SYN URGP=0
IN= OUT=eth0 SRC=MY_IP DST=OTHER_IP LEN=44 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=TCP SPT=1214 DPT=1234 WINDOW=5840 RES=0x00 ACK SYN URGP=0
IN= OUT=eth0 SRC=MY_IP DST=OTHER_IP LEN=44 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=TCP SPT=1214 DPT=1234 WINDOW=5840 RES=0x00 ACK SYN URGP=0
ive removed the IP addresses.

i normally use my own iptables firewall, but recently deicded to give firestarter a go.
i have opened port 1214.

this shows the source port as 1214, destination port as 1234 (the SubSeven Port)

plus im getting huge abounts of SHELL CODE SETUID 0 and x86 NOOP packets.

is this anything to worry about ?
 
Old 10-24-2004, 10:56 PM   #2
Capt_Caveman
Senior Member
 
Registered: Mar 2003
Distribution: Fedora
Posts: 3,658

Rep: Reputation: 69
Why do you have port 1214 open?

That warning is triggered by the use of port 1234, so it's prone to false positives because most systems will use unprivileged ports >1023 as the source port for connections. Since this increments as more connections are made, the use of 1234 is not that uncommon. The shell code and NOP sled in packets is more of a concern, but is that associated with this connection (same IP address, ports, time, etc)? Seeing them randomly due to all the windows malware is quite common and could just be coincidence, but if it's associated somehow with the other traffic then it might be something to be concerned about. Capturing some full packet dumps of the traffic with tcpdump might be informative.
 
Old 10-24-2004, 10:56 PM   #3
chort
Senior Member
 
Registered: Jul 2003
Location: Silicon Valley, USA
Distribution: OpenBSD 4.6, OS X 10.6.2, CentOS 4 & 5
Posts: 3,660

Rep: Reputation: 76
Well there's really no reason why your box should be making connections to arbitrary (or not so arbitrary) high ports on another box. The shellcode attacks could be worrisom if they're going to services on your box that could be vulnerable. It's probably a good idea to check for rootkits at this point and start looking into where all that shellcode is being directed. There's a fair chance that you have exploitable services running.
 
Old 10-24-2004, 11:25 PM   #4
Capt_Caveman
Senior Member
 
Registered: Mar 2003
Distribution: Fedora
Posts: 3,658

Rep: Reputation: 69
Those are outbound replies, no? Look like response packets to incoming connection attempts to port 1214 on his system.
 
Old 10-25-2004, 01:42 AM   #5
chort
Senior Member
 
Registered: Jul 2003
Location: Silicon Valley, USA
Distribution: OpenBSD 4.6, OS X 10.6.2, CentOS 4 & 5
Posts: 3,660

Rep: Reputation: 76
Whoops, yeah I didn't scroll all the way to the right. Sure enough that's trying to complete the handshake. By the way, 1214 is usually associated with Kaaza, so it could be a file sharing client running locally and some remote host connecting to it in an attempt to view shared files.

Whether the shellcode stuff is something to be worried about depends entirely on what service it's targeting. I've seen a lot of shellcode hitting my Apache server for the last several months, but it targets an IIS vulnerability so it's not concerning at all. On the other hand, if it targeted PHP and mod_php is loaded, that could be troubling.
 
Old 10-25-2004, 08:42 AM   #6
qwijibow
LQ Guru
 
Registered: Apr 2003
Location: nottingham england
Distribution: Gentoo
Posts: 2,672

Original Poster
Rep: Reputation: 47
the shellcode is all from the same IP, and comming in large bursts. but it is going to a high port which is stealthed by by firewall, and has no services listening on it.

thanks... ill check for rootkins next time i powerdown (with knoppix)
whats worrying me is the way someone is sending shellcode to a firewalled port with no servies running.

maybe this guy was confusing my ip with anouther ?
or maybe a root kit falsifying "iptables -vL" and "netstat -l" output ????

anyways.. thanks for the replys.
 
Old 10-25-2004, 12:40 PM   #7
Capt_Caveman
Senior Member
 
Registered: Mar 2003
Distribution: Fedora
Posts: 3,658

Rep: Reputation: 69
Might want to try a running a scan with chrootkit and/or rootkit hunter while the system up a running as well. If you have a file integrity scanner like tripwire, now would be a good time to run a check.

Also, try performing a port scan of the box from a remote system (a second machine or even one of those free online scans) to see if the firewall is performing as it should. Alternatively you could compare md5 sums of the iptables and netstat binaries to that of "known good" versions to rule out trojans.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Intercept outgoing traffic through a firewall???? macburton Linux - Security 1 10-17-2004 01:10 PM
Lucent LT WinModem - Detected and Configured but won't connect. eBopBob Linux - Hardware 15 09-05-2004 04:15 PM
mandrake 10.0 - linksys eth nic detected - wont connect 2 net keyshawn Mandriva 12 08-15-2004 08:25 PM
firewall outgoing connections hotrodowner Linux - Security 2 02-22-2004 12:51 PM
I need to inhibit outgoing web traffic on the firewall, and leave only Squid, How? mfeoli Linux - Networking 2 02-06-2004 09:54 AM

LinuxQuestions.org > Forums > Linux Forums > Linux - Security

All times are GMT -5. The time now is 04:01 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration