I can't imagine the effort involved in hardening all applications to treat the hostname as untrusted input.
ISPs that sell vservers are really no different from Intel or AMD or whoever makes your CPU -- you trust them completely and totally with your data, your executables, and your entire operating environment. They can inject anything they wish into your system's memory whenever they wish. Making sure the dhcp clients don't allow setting these kinds of hostnames however, that might be a good idea. Enforcing the usual dns guidelines of a-zA-Z0-9-_ might be worthwhile.. Thanks -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to bash in Ubuntu. https://bugs.launchpad.net/bugs/1507025 Title: Shell Command Injection with the hostname Status in bash package in Ubuntu: New Bug description: If the HOSTNAME of the pc contains a shell command , the command will run every time you start a terminal, tty or xterm. The command will also executed every time when you type in some command. If you for example change the directory , it will run again. Exploit Demo : 1) edit "/etc/hosts" to this : 127.0.0.1 localhost 127.0.1.1 `ls>bug` 2) edit "/etc/hostname" to this : `ls>bug` 3) reboot 4) start a terminal 5) Now a file with the name "bug" will in your home folder ! 6) Change the directory to Downloads with "cd Downloads/" 7) Now a file with the name "bug" is in your Downloads ! 8) Remove the file with "rm bug" 9) The file "bug" is still there ! Have a look on the screenshot i have attached. Solution: The hostname should be checked if there are shell commands inside !! By the way : The hostname is not always in the hands of the root. Some people rent "vservers" and the hostname is in the hands of the isp. ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: bash 4.3-14ubuntu1 ProcVersionSignature: Ubuntu 4.2.0-15.18-generic 4.2.3 Uname: Linux 4.2.0-15-generic x86_64 ApportVersion: 2.19.1-0ubuntu2 Architecture: amd64 CurrentDesktop: Unity Date: Fri Oct 16 22:31:46 2015 InstallationDate: Installed on 2015-10-09 (6 days ago) InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20151009) SourcePackage: bash UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1507025/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
