The Gentoo MLDonkey ebuild adds a user to the system with a valid login shell and no password.
|Package||net-p2p/mldonkey on all architectures|
|Affected versions||< 2.9.0-r3|
|Unaffected versions||>= 2.9.0-r3|
MLDonkey is a peer-to-peer filesharing client that connects to several different peer-to-peer networks, including Overnet and BitTorrent.
The Gentoo MLDonkey ebuild adds a user to the system named "p2p" so that the MLDonkey service can run under a user with low privileges. With older Portage versions this user is created with a valid login shell and no password.
A remote attacker could log into a vulnerable system as the p2p user. This would require an installed login service that permitted empty passwords, such as SSH configured with the "PermitEmptyPasswords yes" option, a local login console, or a telnet server.
Change the p2p user's shell to disallow login. For example, as root run the following command:
# usermod -s /bin/false p2p
NOTE: updating to the current MLDonkey ebuild will not remove this vulnerability, it must be fixed manually. The updated ebuild is to prevent this problem from occurring in the future.
October 24, 2007
November 07, 2007: 02