#########################################################

gtkdiskfree insecure temporary file creation

Vendor: http://gtkdiskfree.tuxfamily.org/ (no more avaible)
Advisory: http://www.zataz.net/adviso/gtkdiskfree-09052005.txt
Vendor informed: yes
Exploit available: yes
Impact : low
Exploitation : low

#########################################################

The vulnerability is caused due to temporary file being created 
insecurely. This can be exploited via symlink attacks to create and 
overwrite arbitrary files with the privileges of the user running the 
affected script.

##########
Versions:
##########

gtkdiskfree <= 1.9.3

##########
Solution:
##########

To prevent symlink attack use kernel patch such as grsecurity

#########
Timeline:
#########

Discovered : 2005-09-02
Vendor notified : 2005-09-05
Vendor response : no reponse
Vendor fix : no patch
Vendor Sec report (vendor-sec@lst.de) : 2005-09-05
Disclosure : 2005-09-15

#####################
Technical details :
#####################

Vulnerable code :
-----------------

Take a look at : src/mount.h

23 #define TUBE_NAME                "/tmp/gtkdiskfree"

Then to : src/mount.c

32 open_cmd_tube (const gchar *cmd, const gchar *mount_point)
33 {
34         gint status;
35         gchar error[MAXLINE], *line;
36         FILE *sh, *tmp;
37
38         setbuf(stdout, error);
39         line = g_strconcat(cmd, " ", mount_point, " &> ", TUBE_NAME, 
NULL);
40         sh = popen(line, "r");
41         g_free(line);
42
43         status = pclose(sh);
44
45         if (status == 0) {
46                 remove(TUBE_NAME);
47                 gui_list_main_update(GTK_TREE_VIEW(list_treeview));
48
49                 return;
50         } else {
51                 if ((tmp = fopen(TUBE_NAME, "r")) == NULL) {
52 
gui_list_main_update(GTK_TREE_VIEW(list_treeview));
53
54                         return;
55                 }
56                 if (fgets(error, MAXLINE-1, tmp) == NULL) {
57                         fclose(tmp);
58                         remove(TUBE_NAME);
59 
gui_list_main_update(GTK_TREE_VIEW(list_treeview));
60
61                         return;
62                 }
63                 fclose(tmp);
64                 remove(TUBE_NAME);
65                 error_window(error);
66         }
67         gui_list_main_update(GTK_TREE_VIEW(list_treeview));
68
69         return;
70 }

#########
Related :
#########

Bug report : http://bugs.gentoo.org/show_bug.cgi?id=104565
CVE : No CVE

#####################
Credits :
#####################

Eric Romang (eromang@zataz.net - ZATAZ Audit) - Gentoo Security Scout
Thxs to Gentoo Security Team.