bsd-games: Local privilege escalation in tetris-bsd

Background

bsd-games is a collection of NetBSD games ported to Linux.

Description

Tavis Ormandy of the Gentoo Linux Security Audit Team discovered that the checkscores() function in scores.c reads in the data from the /var/games/tetris-bsd.scores file without validation, rendering it vulnerable to buffer overflows and incompatible with the system used for managing games on Gentoo Linux. As a result, it cannot be played securely on systems with multiple users. Please note that this is probably a Gentoo-specific issue.

Impact

A local user who is a member of group “games” may be able to modify the tetris-bsd.scores file to trigger the execution of arbitrary code with the privileges of other players.

Workaround

Do not add untrusted users to the “games” group.

Resolution

All bsd-games users are advised to update to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=games-misc/bsd-games-2.17-r1"