It was discovered that sudo's sudoers file parses does not correctly handle group specification in RunasUser. If group was specified in the list (using syntax %group, to allow some user to run commands as any member of the group) and the user was already member of the group, sudo actually allowed the user to run commands as arbitrary system user.

SuSE and upstream bug report: https://bugzilla.novell.com/showbug.cgi?id=468923 http://www.gratisoft.us/bugzilla/showbug.cgi?id=327

This issue was confirmed on multiple 1.6.9 sudo versions. Latest upstream 1.7.0 was reported not to be affected, 1.6.8p12 previously shipped with Red Hat Enterprise Linux 5 was not affected as well. Problem was confirmed on 1.6.9p17 in RHEL5 and Fedora 10.

Upstream patch:

Index: parse.c =================================================================== RCS file: /home/cvs/courtesan/sudo/parse.c,v retrieving revision 1.160.2.21 diff -u -r1.160.2.21 parse.c --- parse.c 2 Nov 2008 14:35:53 -0000 1.160.2.21 +++ parse.c 23 Jan 2009 19:16:55 -0000 @@ -651,9 +651,11 @@ / If the user has a supplementary group vector, check it first. / - for (i = 0; i < userngroups; i++) { - if (grp->grgid == usergroups[i]) - return(TRUE); + if (strcmp(user, username) == 0) { + for (i = 0; i < userngroups; i++) { + if (grp->grgid == usergroups[i]) + return(TRUE); + } } if (grp->grmem != NULL) { for (cur = grp->grmem; cur; cur++) {

sudo 1.6.x before 1.6.9p21 and 1.7.x before 1.7.2p4, when a pseudo-command is enabled, permits a match between the name of the pseudo-command and the name of an executable file in an arbitrary directory, which allows local users to gain privileges via a crafted executable file, as demonstrated by a file named sudoedit in a user's home directory.

The command matching functionality in sudo 1.6.8 through 1.7.2p5 does not properly handle when a file in the current working directory has the same name as a pseudo-command in the sudoers file and the PATH contains an entry for ".", which allows local users to execute arbitrary commands via a Trojan horse executable, as demonstrated using sudoedit, a different vulnerability than CVE-2010-0426.

sudo 1.6.x before 1.6.9p21, when the runasdefault option is used, does not properly set group memberships, which allows local users to gain privileges via a sudo command.