Insightful's S-PLUS Uses Unsafe Temporary Files That May Let Local Users Modify Files or Obtain Elevated Privileges
SecurityTracker Alert ID: 1005896|
SecurityTracker URL: http://securitytracker.com/id/1005896
(Links to External Site)
Updated: Jun 8 2008|
Original Entry Date: Jan 7 2003
Execution of arbitrary code via local system, Modification of system information, Modification of user information, Root access via local system, User access via local system|
Exploit Included: Yes |
A vulnerability was reported in Insightful's S-PLUS statistical analysis package. A local user could modify files with elevated privileges.|
It is reported that the main Sqpe binary and other shell script modules use files in the '/tmp' directory in an unsafe manner. A local user could create a symbolic link (symlink) from a critical file on the system to one of the temporary files (that has a semi-predictable file name). Then, when a target user invokes S-PLUS, the symlinked file will be overwritten by S-PLUS.
It may be possible for the local user to execute arbitrary commands by exploiting this, according to the report.
The vendor has reportedly been notified.
A local user can cause files on the system to be overwritten with the privileges of the target user. A local user may be able to gain elevated privileges.|
No solution was available at the time of this entry.|
Vendor URL: www.insightful.com/products/product.asp?PID=10 (Links to External Site)
Access control error, State error|
|Underlying OS: Linux (Any), UNIX (Any)|
Source Message Contents
Subject: S-plus /tmp usage|
S-PLUS is a Statistical analysis, graphics and programming tool
As installed on UNIX machines, Splus uses files in /tmp in an unsafe way.
The main Sqpe binary, and various shell script modules, use files in /tmp:
open("/tmp/__F8499", O_RDWR|O_CREAT|O_TRUNC, 0666) = 3
Clobbers /tmp/SUBST$PID.TXT /tmp/ed.cmds$PID
May clobber and use /tmp/file.1 /tmp/file.2
May clobber and use /tmp/file.1
Clobbers /tmp/sgml2html$$tmp /tmp/sgml2html$$tmp1 /tmp/sgml2html$$tmp2
Suppose an attacker creates a symlink from any of the "clobbered" files to
one owned by the victim: guesses the PID that will be used, does
ln -s ~victim/.profile /tmp/__F123
and waits for the victim to use Splus, then the victim's .profile will be
trashed. Some or all of these attacks may then be escalated to arbitrary
command execution; if root ever uses Splus then the damage is much greater.
It might be argued that it is hard to guess what PID will be used next.
It is easy enough to create a few thousand symlinks with likely PIDs; in
fact the attacker could create a symlink for every possible PID (as these
normally range from 0 to 32k or 64k).
5 Dec 2002 StatSci/Insightful notified about shell scripts
9 Dec 2002 Insightful notified about Sqpe
11 Dec 2002 We are currently investigating
17 Dec 2002 continuing to look into your queries
18 Dec 2002 anticipate tmpfile() ... in the next release
26 Dec 2002 Another list might be http://www.biostat.wustl.edu/s-news/
The scripts could be patched trivially using one of the textbook methods,
e.g. using a safe directory:
mkdir -m 700 /tmp/mydir$$ || exit 1
... do things to /tmp/mydir$$/myfile ...
rm -rf /tmp/mydir$$
Fixing Sqpe is harder. Could (safely) pre-create /tmp/__F$$ e.g.:
*** splus/6.0/cmd/NEW.old Tue Oct 10 16:06:37 2000
--- splus/6.0/cmd/NEW Tue Dec 24 09:15:59 2002
*** 9,13 ****
--- 9,19 ----
echo $target not found; exit 1
+ set -e
+ umask 077
+ mkdir /tmp/F$$
+ touch /tmp/F$$/__F$$
+ mv -i /tmp/F$$/__F$$ /tmp </dev/null
+ rmdir /tmp/F$$
but Sqpe would still be open to races as it repeatedly open()s and
unlink()s that file. A proper fix will have to come from the vendor.
Paul Szabo - email@example.com http://www.maths.usyd.edu.au:8000/u/psz/
School of Mathematics and Statistics University of Sydney 2006 Australia