Knocking Infected PCs Off the Internet 206
nk497 writes "Malware could block your access to the internet – but in some cases by those on the right side of the security fence, who are deploying tactics such as blocked ports, letters in the mail and PCs quarantined from the net to combat the most damaging threats. The DNS Changer clean up saw some PCs prevented from accessing the web. Should such tactics be used more often to prevent malware from spreading — or is that taking security a step too far?"
That depends upon the infection. (Score:5, Informative)
That depends upon what the infection is.
In many cases, the infection is a worm that attempts to connect to other machines on known ports with known connection strings. This is how network-based Intrusion Detection Systems (IDS) work.
Re:Not just infected PCs... (Score:5, Informative)
The problem is that detecting infected computers invariably requires some level of privacy intrusion, and possibly committing numerous felonies to probe the machine.
In many cases it doesn't. Sometimes it just requires noticing that one customer is responsible for 30% of all traffic flows in a particular core router. You can call that privacy intrusion, but in most of Europe doing flow monitoring is mandated by law, so you might as well run statistics.
And yes, the ISP I work for has in a few cases blocked customer traffic from infected machines. It is a medium-sized ISP, so that can be done without angering the infected customers. It can be difficult to get hold of the right people at the customer, and the large ISP's probably only have billing contacts for most customers.
Re:Herd Immunity and blocking ports (Score:5, Informative)
People who are being spammed by your PC can legitimately use the minimum force necessary to stop the harm, not including shooting it or you. This is the starting point in law: a harmed individual, who has some limited rights to respond in self-defense.
If your PC is trying to infect theirs, they can tell the local board of health, and have have you asked to quarantine yourself until the disease is cured. In this case, the board of health is the ISP, and they're asking you every time you try to send spam/viruses. They're allowed to wear a surgical mask while asking, as well, in this case over their port 25. They're not allowed to put you in an impervious plastic bag to stop you from breathing: that's not minimum force.
If you or your PC resists being quarantined, they can apply to the courts for an order to have the PC locked up and treated against it's will. That'a a real court, with real judges and court orders, not an ISP. In that case you can argue against it, but you'd better have a legally valid reason, not "you can't do that to me". And if necessary you can object, and argue it out before a judge.
--dave
Re:It should be more than obvious (Score:4, Informative)
This will be abused. Life is too short to list how and why. Let's just say that people will be knocked off (up?) for expressing something "offensive". Feel free to define that as you wish. The authorities and fanbois will.
Well the current situation is definitely abused... Now the question of course is what kind of a solution is used to treat the problem, but personally I'd like to be notified if I had a contagious desease that I did not know about and could be harmful for me too.
Here's how one ISP handled it: http://www.net-security.org/article.php?id=1703 [net-security.org]
Re:Not just infected PCs... (Score:5, Informative)
The problem is that detecting infected computers invariably requires some level of privacy intrusion, and possibly committing numerous felonies to probe the machine. That's why only large organizations do this; because they own all the machines and can dictate that policy. It's entirely another matter when the system isn't owned by you, and that's what's under discussion.
The company I work for block computers with certain malware off the network, and also block computers running torrents (after which you get a polite visit from the IT department) . It does this ONLY through network traffic analysis. Viruses/malware need to create network traffic to spread. Also many of them contact a "home" server. There is a rootkit out now which is only detectable through network analysis. No intrusion on the PC. Just looking at network packages.
Re:It should be more than obvious (Score:5, Informative)
First, how do you know my PC doesn't mean to send out thousands of emails an hour? That may come from an infection; I could works as a (semi-legitimate) spammer; or perhaps it just means I run a large listserv. How do you know that I don't mean to port-scan thousands of IPs per hour? That could come from an infection; I could work as a researcher collecting vulnerability statistics; or I might work as a consultant paid to do penetration testing for dozens of companies on an ongoing basis. Opting for a "solution" that would also block legitimate activity counts as a great big "no-no".
Actually, my terms of service forbid most of what you describe. Want to do that? Get a business subscription.