net-snmp 'fixproc' Unsafe Temporary File Lets Local Users Gain Elevated Privileges
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SecurityTracker Alert ID: 1014039
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SecurityTracker URL: http://securitytracker.com/id?1014039
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CVE Reference: GENERIC-MAP-NOMATCH
(Links to External Site)
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Date: May 24 2005
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Impact: Execution of arbitrary code via local system, Root access via local system
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Vendor Confirmed: Yes
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Version(s): 5.2.1 and prior versions
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Description: Eric Romang (ZATAZ) reported a vulnerability in net-snmp in the fixproc utility. A local user may be able to gain elevated privileges.
The fixproc component creates a temporary file in an unsafe manner and then executes the contents of the file. A local user can
execute arbitrary commands with root privileges.
The vendor was notified on May 17, 2005.
The original advisory is available
at:
http://www.zataz.net/adviso/net-snmp-05182005.txt
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Impact: A local user can execute arbitrary commands with root privileges.
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Solution: A final solution was not available at the time of this entry. A proposed patch is available from the vendor at:
http://sourceforge.net/tracker/index.php?func=detail&aid=1203376&group_id=12694&atid=112694
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Vendor URL: net-snmp.sourceforge.net/ (Links to External Site)
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Cause: Access control error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: "ZATAZ.net" <exploits@zataz.net>
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Message History:
None.
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Source Message Contents
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Date: Mon, 23 May 2005 22:59:31 +0200
From: "ZATAZ.net" <exploits@zataz.net>
Subject: net-snmp fixproc insecure temporary file creation
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
#########################################################
net-snmp fixproc insecure temporary file creation
Vendor: http://www.net-snmp.org
Advisory: http://www.zataz.net/adviso/net-snmp-05182005.txt
Vendor informed: yes
Exploit available:no
Impact : low
Exploitation : low
#########################################################
net-snmp fixproc contain a security flaw how could
allow a malicious local attacker to execute arbitrary commands
with root privileges.
##########
Versions:
##########
net-snmp <= 5.2.1
##########
Solution:
##########
Depends the linux distribution you use,
some are patched, some not, the vendor
is looking on a official patch.
#########
Timeline:
#########
Discovered : 2005-05-07
Vendor notified : 2005-05-17
Vendor response : 2005-05-23
Vendor fix : no date
Disclosure : 2005-05-23
#####################
Technical details :
#####################
Just take a look at /usr/bin/fixproc
Line 233 :
# it must be "shell", so execute the shell script defined in database
local ($tmpfile) = "/tmp/fix_$$";
&create_sh_script ($fix{$proc}, $tmpfile);
# return code is number divided by 256
$error_code = (system "$tmpfile") / 256;
- -----------------------------------------
We see that the tmp file is created with $$ value and this script is
execute by the perl system command
The subfunction do only this :
- -------------------------------------
sub create_sh_script
{
local ($file) = pop (@_);
local ($i) = pop (@_);
printf (stderr "create_sh_script\n") if ($debug > 0);
$! = $fixproc_error;
open (file, ">"."$file") || die "$0: cannot open $file\n";
while ( $shell_lines[$i] ne $shell_end_marker )
{
printf (file "%s", $shell_lines[$i]);
$i++;
}
close (file);
system "chmod +x $file";
return file;
}
- ----------------------------------
The same for the fonction do_check()
########
Notice :
########
Take a look on this :
http://rpmfind.net/linux/RPM/suse/9.1/i386/suse/i586/net-
snmp-5.1-80.i586.html
* Tue Mar 16 2004 - ro@suse.de
- use mktemp in fixproc (#36103)
#########
Related :
#########
http://sourceforge.net/tracker/index.php?
func=detail&aid=1203376&group_id=12694&atid=112694
http://bugs.gentoo.org/show_bug.cgi?id=91792
#########
Credits :
#########
Eric Romang (eromang@zataz.net - ZATAZ Audit)
Thxs to Gentoo Security Team. (Taviso, jaervosz, solar, tigger, etc.)
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