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Worm Claimed For Apple OS X
SkiifGeek writes "Controversy is slowly building over the development of a claimed new worm that targets OS X systems, dubbed by its inventor Rape.osx. Using a currently undisclosed vulnerability in mDNSResponder, the worm is said to give access to root as it spreads across the local network. As with a number of recent Apple-related security discoveries, the author, InfoSec Sellout, is delaying reporting the vulnerability to Apple until after completing full testing of the worm. While the worm has yet to leave a testing environment (with 1,500 OS X systems), it is bound to join the likes of Inqtana and Leap as known OS X malware."
mDNSResponder is open source.
If this is a real concern, there is a workaround to have mDNSResponder run without root privileges. Part of the claim is that they can deliver root payloads - this is likely because mDNSResponder runs as the root user and they might be using a buffer overflow exploit [NOTE: I have not analyzed the mDNSResponder code - this is a guess.]
/System/Library/LaunchDaemons/com.apple.mDNSRespon der.plist /usr/sbin/mDNSResponder /usr/sbin/mDNSResponder /System/Library/LaunchDaemons/com.apple.mDNSRespon der.plist
% sudo launchctl unload
% sudo chown nobody:wheel
% sudo chmod 4750
% sudo launchctl load
If someone wants an explanation of what the above commands accomplish, please read further.
1. launchctl is used to unload and load the mDNSResponder daemon.
2. We change the owner of the mDNSResponder to nobody and ensure that wheel is the group. The group is used to ensure that members of the wheel group may launch mDNSResponder and not other users of the system (with the exception of root and anything else running as nobody.)
3. We change the permissions of the mDNSResponder program to be setuid nobody. This means that mDNSResponder will run as nobody and only be able to affect files owned by that account or by files it may happen to have write privileges against.