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Stopping NetBIOS Spam?
MoonFacedAssassin asks: "I woke up this morning to find that my computer had a Windows messaging pop-up window with an advertisement about getting diplomas and degrees. I was quite shocked to find that my Bellsouth DSL IP address had been spammed. Has this happened to anyone else? Other than closing off the port which this can come through, are there any other ways to block this spam? And, how responsible is Bellsouth (or any ISP for that matter) in handling issues like this?"
Are you new?
Seems to me that restricting the port would be the sane method of preventing outside persons from exploiting your system. The same as any other service on any other port.
i hate pansy republicans
On Windows NT/2000/XP, stop the messaging service and enjoy ;-)
TechTV covered this earlier this year so you might want to read their breif article for more information.
Basically, they're port scanning for open port 139s and spam IP that comes up positive. Either turn off the messenger service in services or install a firewall/router and block incoming tcp connections on port 139 (NetBIOS).
While you're at it, turn off the remote registry service...
Block the port. To be honest, I can't understand why you would leave any ports open, when on an always-on connection, with a static IP address. Unless you have a service running on a port, that you want it to be public accessible, all other ports should be blocked and stealth. Experience says this is especially true for netbios ports...
As for the second part, you cannot count on an ISP's usage terms to protect you from malicious acts. For good or for bad, they sell access services, not security services.
Especially not if you don't know how to configure it. There's even a GUI for disabling NETBIOS.
Jilles
Dear Slashdot,
When I go to work, I leave my front door unlocked and slightly ajar. The other day when I got back, I found vagrants sleeping on my sofa and defecating in my sink. Other than closing and locking my door when I leave, how can I get rid of them? Has this ever happened to you? Also, can I sue my landlord over this? Thanks.
Yours,
Confused in Cleveland
I have 2 Windows computers at home that have public static IPs. Instead of using my DSL router on the windows machines, I've given them local IP addresses (192.168.*.*) and route them through my Linux server. There I've put up an iptables firewall with DNAT and SNAT, so that when the windows computers are routed through the firewall, they get their public IPs assigned to them, and you can access the computers from the outside with the public IPs. On the Linux router I've added tons of rules, and one of the most important rule is the one that blocks ports 0-1024 on all windows machines. All important ports are usually below 1024, so I can basically run filesharing, etc. without having to worry about users accessing the files from the Internet (or accessing windows messaging). However, since all ports above 1024 are unblocked, and have a public IP due to the SNAT, the users on the windows machines can use P2P apps, play games online, etc. since their machines are accessible from the outside. This has worked extremely well for a long time, no need for firewalls on the windows boxes (like Norton Internet Security). I haven't experienced any viruses, hackers or unwanted pr0n sent to the printers because of open ports. :-)
Spam Takes New Form
Most decent DSL/CABLE Modem providers block the netbios ports these days...thats just sad that they have those ports open and avialable for traffic on thier network.
Hint: Get a linksys router and those ports will no longer be available for spam...
Hint2: Don't leave windows machine hanging on the wire like that unless they are memebers of NT domain. It will stepup the security of the Netbios connections.
Hint3: Not ever leave an improperly secured NT machine hanging on the wire like that....
Hint4: see hint 1
Power Corrupts,Absolute Power Corrupts Absolutely, leaving one person(group)in charge is absolutely corrupt.
Your so-called "Senior Security Engineer" needs to get a little more training. Port 135 has absolutely nothing to do with the Windows Messenger service.
Port 135 is the RPC/DCOM portmapper in Windows. It performs the exact same service that port 111 does on a Unix box offering RPC services. It allows remote RPC calls to "find" the dynamically assigned port that their target service is running on.
Windows Messenger does not use RPC or DCOM. It uses part of the same protocol that SAMBA uses.
This stupid question (block the port, be done with it) has given me a potentially useful idea.
How hard would it be to send a message back to the boxes that have some code red or similar virus. Basically you ask my web server for c:/scripts/something, you get a Windows message back informing you in no uncertain terms that your box is infected and the OS needs to be reinstalled.
This isn't an attack, but if enough people did it (just one message per infection attempt) people would soon be forced to do something because of the barrage of messages. And the people who let their boxes REMAIN infected with a virus that's been out in the wild for over a year are hardly the type of people to have locked down port 139.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
OK, please do not regard this as bashing. It's just the correct answer to anyone with this problem - if you don't like it, the problem is not in the answer.
NETBIOS CANNOT BE SECURED. If you leave your netbios ports open, you can be cracked to such a degree that it will be impossible for anyone other than a forensic analyst (who will boot from a linux or BSD boot disk) to detect. Netbios is only a viable solution on TRUSTED networks, which the Internet isn't, by definition.
YOU ARE PROBABLY OWNED. Your machine is most likely already completely compromised, and is happily working on cracking RC5 ciphers for somebody you've never met. See the honeynet project for more information (incidentally, one of the founders of honeynet reportedly got cracked by el8; everybody can make mistakes).
YOUR BEST OPTION IS TO FORMAT YOUR HARD DRIVE. The fastest, most reliable way to remove any possibility of a problem is to reload your system from a read-only media - i.e. your windows distribution disk. You must scrub the hard drive first, though; there are programs that can survive windows reinstallation unless this step is taken. You must also disconnect your Internet connection until you have a firewall running, to be absolutely safe; you should buy the firewall or get a friend with a more secure system to download one for you, since anything you download with your machine is suspect.
Hope this helped!
Give me a break. Install Redhat 7.2 on PC, then plug that straight into the internet and tell me how long it takes to get r00ted. It took me all of 2 minutes at my last job.
A good start would be a decent software firewall. Tiny Software used to offer theirs for free for personal use, but seem to have taken it down from their website =(. If you scour the net, you might be able to find it for download from one of those shareware sites.
A reinstall also would be prudent. When I'm doing a fresh install I try to keep the machine behind a device doing NAT until I have proper firewall software installed and my box patched.