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SA-20031006 slocate vulnerability



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Security advisory 20031006
- ----------------------------------------------------------------------
  Product:                  slocate
  Vulnerability type:       buffer overflow (corrupt heap)
  Extended type:            possibly gaining elevated privileges
  Severity:                 low
  Issue date:               2003/10/06
  Last updated:             2003/10/06
======================================================================



Description
- -----------

Mr.  Hornik  has  discovered  buffer overflow vulnerability in slocate
version 2.6. Many Linux distributions have their slocate package based
on  this  version.  We found at least RedHat package to be vulnerable.
The  vulnerability  corrupts  heap  management structures and possibly
leads to gaining slocate group privileges, which allows reading global
slocate database and thus obtaining list of all files in the system by
unauthorized user.


Vulnerability
- -------------

Program slocate works on user supplied database with setgid to slocate
group.  With  user  prepared  slocate  database  one can cause (we are
reffering to source lines from slocate-2.6-1.src.rpm from RH 7.3) that
pathlen  after  executing  main.c:1255  will have value -1. It must be
caused by not the first path in the database because it is verified in
validate_db.  Then  on  line main.c:1275 the last byte of memory block
header  (this memory block size) will be overwritten with user suplied
value. The codedpath is never freed by the code, but it is possible to
trigger realloc on line 1269 later by data in database.

Because  of  not freeing some dynamic memory, using multiple databases
and  multiple  search  patterns  it should be possible to prepare heap
before  triggering  this  vulnerability  to  allow  later execution of
arbitrary  code,  thus  gaining  slocate group privileges. This allows
reading  of  global  slocate  database  with  list of all files in the
system  by  unauthorized  user.  The  exploit is not available at this
time.

Suggested  and  correct  patch  is to change condition on line 1263 to
pathlen <= 0.


Who is affected?
- ----------------

Affected are all RedHat distributions up to version 9.0 including.

slocate  version  2.6 and below is vulnerable. slocate version 2.7 and
all packages based on this version are not vulnerable.


Recommendations
- ---------------

We  recommend to upgrade slocate package to the fixed version.

If  obtaining the list of all files on the system by unauthorized user
is  security  risk  for  your  system  we  recommend to remove slocate
database  and  disable automatic generation of this database (as daily
cron  job)  or  remove  slocate utility or generate database only from
safe files until fixed version is installed.


References
- ----------

This security advisory:
http://www.ebitech.sk/patrik/SA/SA-20031006.txt


Contact
- -------

Patrik Hornik
- --
Security Consultant

Email: patrik.hornik@xxxxxxxxxx
Phone: +421 905 385 666
PGP KeyID: DFA5BC67

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