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Bugtraq archives for 1st quarter (Jan-Mar) 1998: serious security hole in KDE Beta 3

serious security hole in KDE Beta 3

Tudor Bosman (tudorbCCO.CALTECH.EDU)
Fri, 6 Feb 1998 20:06:52 -0800 

Hello !

When using shadow passwords, the K Desktop Environment
(http://www.kde.org) screen savers require to be setuid root (in order
to access /etc/shadow).  However, they never drop root privileges...

When starting, they create the file .kss.pid in the home directory as
root, following symbolic links.  And ln -s /etc/shadow ~/.kss.pid
will cause /etc/shadow to be overwritten.

A short patch:

diff -c kscreensaver.orig/main.cpp kscreensaver/main.cpp
*** kscreensaver.orig/main.cpp  Fri Feb  6 19:23:07 1998
--- kscreensaver/main.cpp       Fri Feb  6 19:30:13 1998
***************
*** 289,294 ****
--- 289,298 ----

        initPasswd();

+       // this makes use of the POSIX saved UIDs feature, available
+       // in current Linux versions -- tudorbcaltech.edu
+       setuid (getuid ());
+
        if ( mode == MODE_INSTALL )
        {
         if (!canGetPasswd) {

--
Tudor Bosman
E-mail:  tudorbits.caltech.edu   Phone: (626) 683-3813
Address: Caltech MSC #345, Pasadena, CA 91126-0345, USA