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silc server and toolkit insecure temporary file creation
Vendor: http://silcnet.org/
Advisory: http://www.zataz.net/adviso/silc-server-toolkit-06152005.txt
Vendor informed: yes
Exploit available: yes
Impact : low
Exploitation : low
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The vulnerability is caused due to temporary file being created insecurely.
This can be exploited via symlink attacks in combination to create and
overwrite arbitrary files with the privileges of the user running the
affected script.
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Versions:
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silc-server <= 1.0
silc-toolkit <= 0.9.12-r3
##########
Solution:
##########
To prevent symlink attack use kernel patch such as grsecurity
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Timeline:
#########
Discovered : 2005-05-31
Vendor notified : 2005-06-15
Vendor response : none
Vendor fix : none
Disclosure : 2005-09-01
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Technical details :
#####################
Vulnerable code :
-----------------
In silcd/silcd.c
258 /* Dump server statistics into a file into /tmp directory */
259
260 SILC_TASK_CALLBACK(dump_stats)
261 {
262 FILE *fdd;
263 char filename[256];
264
265 memset(filename, 0, sizeof(filename));
266 snprintf(filename, sizeof(filename) - 1, "/tmp/silcd.%d.stats",
getpid());
267 fdd = fopen(filename, "w+");
268 if (!fdd)
269 return;
270
271 #define STAT_OUTPUT(fmt, stat) fprintf(fdd, fmt "\n", (int)stat);
272
273 fprintf(fdd, "SILC Server %s Statistics\n\n", silcd->server_name);
274 fprintf(fdd, "Local Stats:\n");
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Related :
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Bug report : http://bugs.gentoo.org/show_bug.cgi?id=94587
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Credits :
#####################
Eric Romang (eromang@xxxxxxxxx - ZATAZ Audit)
Thxs to Gentoo Security Team. (Taviso, jaervosz, solar, etc.)
