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We often ask to post the output of network-related commands to diagnose and resolve a problem. Even after the problem is resolved, all this information remains available to any Internet user and can also be indexed by public and private search engines.

The output of some commands may contain sensible IDs and IP addresses, allowing the local or remote fingerprinting of the user's host: an unexperienced user is an easy target for crackers who may compare the question content with the result of a network fingerprinting (for example an Nmap active scan). This is the first step for social engineering and vulnerability exploiting.

Since an user may not know which information is dangerous to share, I propose to add an option to flag explicitly every question that contains sensible data and that (if possible) those questions should be hidden until the sensible information is removed.

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    Possibly relevant: askubuntu.com/q/435261/85695 – terdon Sep 28 '16 at 12:09
  • I do not see that serial numbers or IP addresses are "sensible". – Pilot6 Sep 28 '16 at 13:11
  • @Pilot6 the law states that the IP address is considered personal and sensible information in conjunction with other unique identifiers. – Lorenzo Ancora Sep 28 '16 at 14:09
  • Surprisingly here in Russia we have exactly same stupid law. No matter how stupid it is the purpose of the law is quite different from what you think it is. Personal information should not be distributed by companies who collect it. The definition of personal information is very generic. Can you tell practically what is a problem if everyone knows your network card serial number together with you IP address? ))) – Pilot6 Sep 28 '16 at 14:17
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    @LorenzoAncora Questions here would normally only contain private IP addresses anyway, and you don't gain anything if you know that one's computer has the local IP 192.168.0.42 in their home LAN. It's more often a problem that people deliberately post their email addresses or other personal or contact data in hope to receive more replies. – Byte Commander Sep 30 '16 at 23:56
  • @ByteCommander I agree, we also have the problem of users deliberately disclosing their contact data, but it is a situation where they actually know what they are doing, so it is their responsibility (unless, of course, they violate the SE policy). The private IPs are a secondary problem with "home" users, but a LAN segment can handle up to 253 PCs: if the user is posting from a computer at work and there are IDs in the post (like MAC, BSSID of the router, serials etc.) anyone who has access to the LAN can identify the user with precision. If the LAN does not use DHCP, only the IP is needed. – Lorenzo Ancora Oct 1 '16 at 9:10
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Moderators can redact sensitive information to permanently remove something from the site. If you see something you think is a serious issue, flag it up. We can't stop archiving services (eg Wayback) keeping their copy.

But what sort of combination of data are you talking about here? I don't think we can (or should) redact every post with an IP or MAC address. Yeah they could help a targeted attack, just as letting somebody know your website or email address.

When does this transition from useful debug to when we need to take action?

Just going to pull some of my thinking back in from the comments. An IP address can give attackers some access and some information but there are a hundred ways to pump somebody for their IP address. Devices leak connections out everywhere, people leak it inadvertently (ever opened a link without knowing what was at the end?).

If somebody wants us to redact something they posted after the fact, we're more than happy to help but I just don't think it's useful to try and redact all this stuff on a global scale.

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    A while back, I posted an alert in chat that there was a question with a private key to a VPN server. That revision was nuked from orbit within 30 seconds :) – Android Dev Sep 28 '16 at 12:13
  • Thank you for you answer. I'm talking of the output of commands like: netstat, lspci -v, ifconfig, iwconfig ecc. In fact they contain public and private IP addresses, access-point unique addresses that in conjunction with some public AP maps can be used to determinate the exact position of the user (this is dangerous), unique hardware identifiers and firmware informations. I've managed to locate (for fun) a couple of AskUbuntu users some time ago and if I can also the bad guys can with a little effort. :-/ – Lorenzo Ancora Sep 28 '16 at 12:40
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    No I don't think so. What makes it dangerous is somebody targeting you. There are many other ways to collect the IP address of somebody if you have even a single point of activity. I realise that's a "guns don't kill people" argument but if this sort of stuff worries you, don't post it. We'll even redact it for you if you think you've said too much, but wholesale cleanup of every post with a public IP or MAC address is too far. – Oli Sep 28 '16 at 13:01
  • @Oli your argument is right only when the user knows how the Internet works. The average user doesn't even know that is spreading sensible info in public. If we don't know the user's private life, in doubt, we should protect him (at least on AskUbuntu) and treat the information leak as a special condition that needs a cleanup action. – Lorenzo Ancora Sep 28 '16 at 13:21
  • @LorenzoAncora What is a problem if a network adapter serial number is known? – Pilot6 Sep 28 '16 at 13:40
  • @LorenzoAncora I'd argue that people are even more likely to leak their own IP out to people when they don't know what they're doing. They're much more likely to do something they're told to do by an attacker. – Oli Sep 28 '16 at 13:51
  • @Pilot6 thank you for your interest, I've already answered here: depending on the victim's network, in conjunction with other unique info they allow the fingerprinting (local, often remote) of an host, so the cracker can track and attack specific Internet users, with the advantage of knowing the firmware/software implementations. Linux (our beloved kernel) might be tuned to prevent this, but this is not a thing that average users do. – Lorenzo Ancora Sep 28 '16 at 14:28
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    @LorenzoAncora It looks like you personal fantasies. I can give you my IP address with all other personal data you want. I do not see any way that it may be harmful except a DDoS attack, that is possible anyway. – Pilot6 Sep 28 '16 at 14:40
  • @Oli ...I agree, and I think that great part of the AskUbuntu users simply copy-paste the commands to solve a problem: learning Unix and Linux can be a long road and only few people has the patience to "read the manual" of every command. Sad but true. An attacker may ask them to execute a command, but this is out of our control: we should only prevent AskUbuntu from becoming a source of sensible information by doing what we can do and this will be much easier with a specific flag and a specific policy. ;-) – Lorenzo Ancora Sep 28 '16 at 14:40
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    It is only your personal opinion that serial numbers are sensitive ;-) You can see lots of them at kernel.org commit messages. Nobody cares. – Pilot6 Sep 28 '16 at 14:42
  • @Pilot6 they are developers with experience, and use testing environments. So they can not care. You may not believe me, I'm only a computer science student and I'm not here to convince anyone on things discussed by professors worldwide, but to propose a clever way of enhancing AskUbuntu. – Lorenzo Ancora Sep 28 '16 at 14:58
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    The serial numbers posted there are from ordinary users who report issues. I posted a lot of those too. This paranoia will not enhance AU in any way. It will give reviewers a lot more work, nothing useful. – Pilot6 Sep 28 '16 at 15:01
  • @Pilot6 I do not agree, also your comments are not constructive, because you are talking only of serial numbers while the problem is wider. I will remove any serial number, MAC address, BSSID, IP etc. in my review queue for the security of the users, because the combination of those information may allows the users to be traced or targeted. The users should not be victims of your carelessness and lack of responsibility. – Lorenzo Ancora Sep 29 '16 at 15:40

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