Good catch Noah, thank you for reporting it. I agree it's important to address this even if your sipx box is behind a firewall. Good network admins will only allow smtp out from specific internal hosts as to restrict where mail destined for the wan can come from. sipx would likely be allowed to mail the wan side to deliver voicemail email, so that puts it at risk for both public and private network attack.
For users wanting to check if you've been exploited I'd suggest running (as root or preceding with sudo) "lastlog -u PlcmSpIp" or "lastlog -u lvp2890". As suggested earlier applying "DenyUsers PlcmSpIp lvp2890" or inversely "AllowUsers <trusted users separated with spaces>" to /etc/ssh/sshd_config and restarting sshd is necessary to plug the hole. Beware that iptables is disabled by default in v4.4 so I recommend running sshd on a non-standard port if you need to leave it disabled. If you do want to use iptables and want to restrict who can use ssh from the outside, add to /etc/sysconfig/iptables something like : -A INPUT -s <trusted IP or dyndns fqdn> -p tcp --dport 22 -j ACCEPT (see http://wiki.sipfoundry.org/display/sipXecs/Firewall+Configuration for more you'll need) Alternatively you could use tcp wrappers by appending "sshd: <trusted IP>" to /etc/hosts.allow and then adding "sshd: ALL" in /etc/hosts.deny. fail2ban or denyhosts would also help tremendously. I prefer DenyHosts because it has the online database feature. Installing logwatch and OSSEC are also very good ideas to catch things like this if you're vigilant about reading the email reports. I've been running OSSEC clients with active response enabled on production sipx 4.4 for a long time without issues. ________________________________________ From: [email protected] [[email protected]] On Behalf Of Noah Mehl [[email protected]] Sent: Friday, November 16, 2012 9:15 PM To: Discussion list for users of sipXecs software Subject: Re: [sipx-users] Hacked SipXecs 4.4 Tony, You know what? I think everyone is clear on YOUR opinion on the matter. In MY opinion, this is a serious bug. I have created a Jira story: http://track.sipfoundry.org/browse/XX-10529 Next time, I would appreciate constructive comments instead of: "This is only a problem for you... You must be doing something wrong… You're not setting a firewall/ids up correctly…." I know I am not the only person who thinks this is a serious issue. ~Noah On Nov 16, 2012, at 7:30 PM, Tony Graziano <[email protected]<mailto:[email protected]>> wrote: That is with ssh open or available from the outside. I still suggest a JIRA... On Nov 16, 2012 6:41 PM, "Noah Mehl" <[email protected]<mailto:[email protected]>> wrote: I would also like to mention: This works for any port, including SIP. There might be huge amounts of SIP piracy across peoples servers. ~Noah On Nov 16, 2012, at 6:27 PM, Alan Worstell <[email protected]<mailto:[email protected]>> wrote: What Noah is posting about is correct. SMTP is listening on 127.0.0.1. However, if you use SSH port redirection, from an outside host you can forward your remote 127.0.0.1:25<http://127.0.0.1:25/> to your own 127.0.0.1:25<http://127.0.0.1:25/>. I just tested this with a development 4.6 server we have, from a system completely off-network: ssh -vN PlcmSpIp@{IP_OF_SIPX_SERVER} -L 25:127.0.0.1:25<http://127.0.0.1:25/> After entering the password PlcmSpIp, I could telnet 127.0.0.1 25 and send mail. I would consider that to be a pretty large security flaw, as every sipx server out there that has SSH Password logins allowed to the world can be used as spam relays. Regards, Alan Worstell A1 Networks - Systems Administrator VTSP, dCAA, LPIC-1, Linux+, CLA, DCTS (707)570-2021 x204 For support issues please email [email protected]<mailto:[email protected]> or call 707-703-1050 On 11/16/12 3:17 PM, Tony Graziano wrote: can you provide the output of: lsof -i | grep LISTEN and post what SMTP is listening to? On Fri, Nov 16, 2012 at 6:11 PM, Noah Mehl <[email protected]<mailto:[email protected]>> wrote: This is my problem: You are arguing with me when you don't understand how SSH port forwarding works. In the exploit I've illustrated, the port is tunneled via SSH. Then on the remote machine (the sipxecs server) the traffic originates as LOCALHOST. That's why it's a OOTB security flaw. I have not made changes to the smtp config. ~Noah On Nov 16, 2012, at 6:02 PM, "Tony Graziano" <[email protected]<mailto:[email protected]>> wrote: There is that too. I keep bringing it up but he skips over it. In a default sipx installation, the output shows: sendmail TCP localhost.localdomain:smtp (LISTEN) and there are no other entries related to SMTP. So again, something is different here than in all the others (remember that kids game?). Why is your installation different? Why is SMTP open to begin with? Why is SMTP open on your system and noone else's? I still don't agree with your assessment. It is the way your firewall and/or sendmail is configured to begin with that is not consistent with the way the system is used. Security is the admin's and certainly port SSH forward can be turned off and the user can be denied. I don't think it very helpful to make changes to secure a system if someone keeps opening holes or changing smtp configs and then opening another case that the system is not secure enough... I'm just saying. You still have neglected to explain why SMTP is open from waaaayyyy back in this thread. Realize the developers list are some of the same people here (I won't dissuade you from posting to it to that list, or opening a JIRA) but realize it can be discussed and decided there is no problem and a change is not warranted, only an implementation decision gone awry. On the other hand, if enough people agree those are two things that can be done by default "in the event someone decides to open SMTP". I'm not a fortune teller. I think it took a lot of your time to find it and to bring it up, and I think its worthy of consideration though. On Fri, Nov 16, 2012 at 5:50 PM, Noah Mehl <[email protected]<mailto:[email protected]>> wrote: Hey! FINALLY, I got some information that's actually usefully to me!!! Where is the JIRA link where I can post a bug? Is there a different mailing list for Sipxecs dev? No, my argument is that two users are created by the SipXecs install: PlcmSIp and lvp2890. These user have passwords set in the /etc/shadow from the install script. I do not believe that this is a Redhat/Centos problem, because they DO NOT ship system users with passwords in /etc/shadow. Or any user with a password in /etc/shadow except for the password one sets for root during install, and the password for the first user during install. Since SipXecs install creates these users, and thereby creates the security issue, part of the user creation should deny those users access to ssh in the sshd_config. That's the only part of this scenario that isn't secure. I will be happy to submit a bug, etc... As it happens, I'm not the first person to be hacked because of this: http://www.mail-archive.com/[email protected]/msg04471.html And it's highly likely that many people have been bitten by this, and no one knew what the cause was. This serves as a warning to ALL SipXecs 4.4.x users: 1. If you have SipXecs 4.4.x 2. You still have the PlcmSIp and lvp2890 users, with unchanged password (which you would by default, not knowing they had been added to your server) 3. Anyone has SSH port access to the server 4. Then you are wide open I don't care how one solves the issue, we have 3 solutions so far: 1. Disable or heavily restrict all ssh access to the machine 2. DenyUsers PlcmSIp lvp2890 in /etc/ssh/sshd_config 3. AllowTcpForwarding no in /etc/ssh/sshd_config I prefer method 2 because I don't want to remove a useful tool in my arsenal (ssh port forwarding), and I don't want to change the default passwords (because of provision stock phones). But I HIGHLY suggest everyone takes a quick look at their settings, because I bet a lot of people are susceptible to this. Thanks. ~Noah On Nov 16, 2012, at 5:37 PM, Tony Graziano <[email protected]<mailto:[email protected]>> wrote: You do realize the other side of this argument is that SSH forwarding is enabled by default on Redhat/Centos and that since you have SSH available to the public at large it also makes this an effective use of your system. I think the place for you to ask for a change is submitting a JIRA and posting a link on the users and dev groups so people can comment and/or vote for this change... add in /etc/ssh/sshd_config by default: AllowTcpForwarding no DenyUsers PlcmSpIp On Fri, Nov 16, 2012 at 5:24 PM, Noah Mehl <[email protected]<mailto:[email protected]>> wrote: Shall I make a screencast to explain? ~Noah On Nov 16, 2012, at 5:20 PM, Noah Mehl <[email protected]<mailto:[email protected]>> wrote: Gerald. That's the security hole. I AM ABLE TO CONNECT TO THE LOCAL SMTP SERVICE ON THE SIPXECS SERVER via SSH remotely using the default user/pass of PlcmSIp, utilizing ssh port forwarding. ~Noah On Nov 16, 2012, at 5:17 PM, Gerald Drouillard <[email protected]<mailto:[email protected]>> wrote: On 11/16/2012 1:57 PM, Noah Mehl wrote: Does nobody on the list know what SSH port forwarding is? I am running the first two commands from a remote machine (connecting to the sipxecs machine) in separate terminals to forward my local 25 port to the sipxecs box, and the 25 port on the sipxecs box locally. The third command is run locally on the remote machine. This exploit gives the remote machine access to port 25 on the SipXecs box even if all other ports are blocked. This could be used for any port that is blocked by firewall, ids, etc, if the remote machine has ssh access to the sipxecs box. ~Noah Do you understand that if your sipx smtp server is only running on localhost that you will not be able to connect to it via telnet/ssh/whatever? -- Regards -------------------------------------- Gerald Drouillard Technology Architect Drouillard & Associates, Inc. http://www.Drouillard.biz<http://www.drouillard.biz/> _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ -- ~~~~~~~~~~~~~~~~~~ Tony Graziano, Manager Telephone: 434.984.8430 sip: [email protected]<mailto:[email protected]> Fax: 434.465.6833 ~~~~~~~~~~~~~~~~~~ Linked-In Profile: http://www.linkedin.com/pub/tony-graziano/14/4a6/7a4 Ask about our Internet Fax services! ~~~~~~~~~~~~~~~~~~ Using or developing for sipXecs from SIPFoundry? Ask me about sipX-CoLab 2013! <http://sipxcolab2013.eventbrite.com/?discount=tony2013> LAN/Telephony/Security and Control Systems Helpdesk: Telephone: 434.984.8426 sip: [email protected]<mailto:[email protected]> Helpdesk Customers: http://myhelp.myitdepartment.net<http://myhelp.myitdepartment.net/> Blog: http://blog.myitdepartment.net<http://blog.myitdepartment.net/> _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ -- ~~~~~~~~~~~~~~~~~~ Tony Graziano, Manager Telephone: 434.984.8430 sip: [email protected]<mailto:[email protected]> Fax: 434.465.6833 ~~~~~~~~~~~~~~~~~~ Linked-In Profile: http://www.linkedin.com/pub/tony-graziano/14/4a6/7a4 Ask about our Internet Fax services! ~~~~~~~~~~~~~~~~~~ Using or developing for sipXecs from SIPFoundry? Ask me about sipX-CoLab 2013! <http://sipxcolab2013.eventbrite.com/?discount=tony2013> LAN/Telephony/Security and Control Systems Helpdesk: Telephone: 434.984.8426 sip: [email protected]<mailto:[email protected]> Helpdesk Customers: http://myhelp.myitdepartment.net<http://myhelp.myitdepartment.net/> Blog: http://blog.myitdepartment.net<http://blog.myitdepartment.net/> _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ -- ~~~~~~~~~~~~~~~~~~ Tony Graziano, Manager Telephone: 434.984.8430 sip: [email protected]<mailto:[email protected]> Fax: 434.465.6833 ~~~~~~~~~~~~~~~~~~ Linked-In Profile: http://www.linkedin.com/pub/tony-graziano/14/4a6/7a4 Ask about our Internet Fax services! ~~~~~~~~~~~~~~~~~~ Using or developing for sipXecs from SIPFoundry? Ask me about sipX-CoLab 2013! [http://www.ezuce.com/image/image_gallery?uuid=61c95dd3-a26d-4363-95b1-131231e1edf0&groupId=284283&t=1340112036507%22+style=%22width:+310px;+height:+310px;]<http://sipxcolab2013.eventbrite.com/?discount=tony2013> LAN/Telephony/Security and Control Systems Helpdesk: Telephone: 434.984.8426 sip: [email protected]<mailto:[email protected]> Helpdesk Customers: http://myhelp.myitdepartment.net<http://myhelp.myitdepartment.net/> Blog: http://blog.myitdepartment.net<http://blog.myitdepartment.net/> _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ LAN/Telephony/Security and Control Systems Helpdesk: Telephone: 434.984.8426 sip: [email protected]<mailto:[email protected]> Helpdesk Customers: http://myhelp.myitdepartment.net<http://myhelp.myitdepartment.net/> Blog: http://blog.myitdepartment.net<http://blog.myitdepartment.net/> _______________________________________________ sipx-users mailing list [email protected]<mailto:[email protected]> List Archive: http://list.sipfoundry.org/archive/sipx-users/ _______________________________________________ sipx-users mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-users/
