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TUCoPS :: Linux :: Apps A-M :: bt656.txt

Abnormal suid behavior in several applications





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Thanks to IBM for being so receptive with these issues.

For those of you that have requested we revive the old "Snosoft" 
advisories we have begun placing our legacy advisories at 
http://www.secnetops.biz as time permits.
-KF

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Secure Network Operations, Inc.           http://www.secnetops.com
Strategic Reconnaissance Team               research@secnetops.com
Team Lead Contact                                 kf@secnetops.com


Our Mission:
************************************************************************
Secure Network Operations offers expertise in Networking, Intrusion 
Detection Systems (IDS), Software Security Validation, and 
Corporate/Private Network Security. Our mission is to facilitate a 
secure and reliable Internet and inter-enterprise communications 
infrastructure through the products and services we offer. 


Quick Summary:
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Advisory Number         : SRT2003-07-07-0913
Product                 : IBM U2 UniVerse
Version                 : Version <= 10.0.0.9 ?
Vendor                  : http://ibm.com/software/data/u2/universe/
Class                   : local
Criticality             : Low  
Operating System(s)     : Only confirmed on Linux (other unix based?)


High Level Explanation
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High Level Description  : Abnormal suid behavior in several applications
What to do              : chmod -s /usr/ibm/uv/bin/uvrestore
chmod -s /usr/ibm/uv/bin/setacc


Technical Details
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Proof Of Concept Status : No PoC necessary
Low Level Description   : 

UniVerse is an extended relational database designed for embedding in 
vertical applications. Its nested relational data model results in 
intuitive data modeling and fewer resulting tables. UniVerse provides 
data access, storage and management capabilities across Microsoft®
Windows® NT, Linux and UNIplatform.

Several several binaries have odd behavior including core dumps and 
changing permissions on device files. 

The intent of the below gdb and strace dumps is only to show why we 
feel these issues are difficult to exploit on linux. We do not feel 
that we are disclosing Intellectual Property in any way. No anti 
debug routines are enforced by the below applications. The point is 
to show what calls are causing the problem. The result could vary on 
a different unix platform or processor. 

uvrestore suffers from a command line overflow:

(gdb) r `perl -e 'print "A" x 6000'`
Starting program: uvrestore `perl -e 'print "A" x 6000'`
Program received signal SIGSEGV, Segmentation fault.
0x0805e81a in basename ()
(gdb) bt
#0  0x0805e81a in basename ()
#1  0x080619b3 in basename ()
#2  0x42015574 in libc_start_main () from /lib/tls/libc.so.6
(gdb) i r
eax            0x41414141       1094795585

...
[0805e6ec] strcmp("AAAAAAAAAAAAAAAAAAAAAAAAA"..., "-noindexfix") = 1
[0805e771] strcmp("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"..., "-") = 1
[0805e7f3] strcpy(0x083b7d00, "AAAAAAAAAAAAAAAAAAA"...) = 0x083b7d00
[0805e815] strcpy(0x083b9100, "AAAAAAAAAAAAAAAAAAA"...) = 0x083b9100
[0805e81a] --- SIGSEGV (Segmentation fault) --- 

uvsetacc does a chmod based on ttyname() results: 

[root@vegeta bin]# ltrace ./uvsetacc 2557
ttyname(1)                                     = "/dev/pts/1"
chmod("/dev/pts/1", 04775)                     = 0

[kf@vegeta kf]$ ls -al /dev/pts/1
crw-------    1 kf       tty      136,   1 Jul  7 21:40 /dev/pts/1
[kf@vegeta kf]$ /usr/ibm/uv/bin/uvsetacc 2557
[kf@vegeta kf]$ ls -al /dev/pts/1
crwsrwxr-x    1 kf       tty      136,   1 Jul  7 21:41 /dev/pts/1

--- farfetched - disgruntled helpdesk worker attack scenario ---

Helpdesk phone *ring*...
uvadm-> hello
boss-> my universe program xyz is acting weird

uvadm finds boss's tty. *grin*
kf       pts/1    -                 9:42pm  1:02   0.16s  0.16s  /bin/bash

[uvadm@vegeta uvadm]$ id
uid=503(uvadm) gid=503(uvadm) groups=503(uvadm)
[uvadm@vegeta uvadm]$ cat /dev/pts/1
cat: /dev/pts/1: Permission denied

uvadm-> hrmm try typing this and lets see what happens... 
"/usr/ibm/uv/bin/uvsetacc 2559"
boss-> ok I typed it... now what? 
uvadm-> do you see the password prompt?

[uvadm@vegeta uvadm]$ ls -al /dev/pts/1
crwsrwxrwx    1 kf       tty      136,   1 Jul  7 21:48 /dev/pts/1
[uvadm@vegeta uvadm]$ echo Enter Your Universe Password: >> /dev/pts/1

boss-> oh yeah hold on let me type the password in. 
...

In order to exploit the uvsetacc behvior, you must be logged in as user 
uvadm. The creation and use of the Unix  user 'uvadm' is optional for 
UniVerse. It is not required for the successfull installation, configuration 
and administration of UniVerse. The intended use of uvadm is to allow a 
selected, specific non-root user to perform all aspects of UniVerse 
administration.

Patch or Workaround     : chmod -s /usr/ibm/uv/bin/uvrestore
chmod -s /usr/ibm/uv/bin/setacc

Vendor Status           : The IBM U2 staff will have this issue resolved 
in a future release of IBM U2. Patches may also be supplied on a per 
client basis at IBM's disgression. 

Bugtraq URL             : to be assigned

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This advisory was released by Secure Network Operations,Inc. as a matter
of notification to help administrators protect their networks against
the described vulnerability. Exploit source code is no longer released
in our advisories. Contact research@secnetops.com for information on how
to obtain exploit information.



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