Re: Supplied Packages, Database Links, and SQL Injection

But be careful, I've encountered several situations where revoking privileges (according to oracle recommendation) breaks certain oracle components. One example is Grid Control, which recommends you to revoke several packages (utl_file, utl_tcp) from public, which in turn breaks Grid Control itself.

Just my 2 cents.

On 5/9/06, Hostetter, Jay M <JHostetter_at_decommunications.com> wrote:
>
> These are the standard revokes that I issue. If a user needs it, I
> grant it directly to that user. I put these revokes right into
> postDBCreation.sql that is generated by DBCA.
>
> /* Revoke privileges per page 715 of the Admin Manual (Security
> Checklist). */
> revoke execute on utl_smtp from public;
> revoke execute on utl_tcp from public;
> revoke execute on utl_http from public;
> revoke execute on utl_file from public;
> revoke execute on dbms_random from public;
>
> /* From Oracle9i Application Developer's Guide - Fundamentals Ch. 14 */
> revoke execute on dbms_obfuscation_toolkit from public;
>
> /* Oracle Database Security Benchmark v1.1 */
> revoke execute on dbms_lob from public;
> revoke execute on dbms_job from public;
>
> Some new revokes to consider:
>
> /* Related to CPUApr2006 -
> http://www.red-database-security.com/advisory/oracle_cpu_apr_2006.html
> */
> revoke execute on dbms_reputil from public;
> revoke execute on dbms_snapshot_utl from public;
> revoke execute on dbms_export_extension from public;
>
> You are right - it's fairly easy to find existing stored objects that
> will break if you make these revokes. It's a bit more difficult for the
> anonymous blocks. I modified an old query for v$db_object_cache in an
> attempt to find out if one of these packages was called recently. I'm
> sure somebody could improve upon it:
>
> select owner || '.' || name OBJECT
> , type
> , to_char(sharable_mem/1024,'9,999.9') "SPACE(K)"
> , loads
> , executions execs
> , kept
> from v$db_object_cache
> where name in ('UTL_SMTP','UTL_TCP','UTL_HTTP','UTL_FILE','DBMS_RANDOM',
> 'DBMS_OBFUSCATION_TOOLSKIT','DBMS_LOB','DBMS_JOB')
> order by owner, name
> ;
>
> Jay
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org
> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of MacGregor, Ian A.
> Sent: Tuesday, May 09, 2006 2:18 PM
> To: oracle-l
> Subject: Supplied Packages, Database Links, and SQL Injection
>
> Certain supplied packages such as dbms_export_extension are flawed, you
> can inject SQL such as "grant dba to me;" into them and the code will
> be executed. Now suppose you are pulling data from a database which
> includes sensitive information to one that does not via a database link.
> No sensitive data is accessible, the account on the sensitive database
> to which the database link connects has no privilege to access the
> sensitive objects. However there is a package, I'll call it dbms_flawed
> which is exploitable via SQL injection. A user runs
> dbms_flawed.exeute_this_at_remote_db('grant dba to me') thereby gaining
> that privilege or execute dbms_flawed.execute_at_remote_db('grant all on
> trusted_user.cofidential_info_table to me'); The controls setup to
> prevent improper access are bypassed.
>
> The answer is to to not allow "me" to execute dbms_flawed. However,
> there are other packages which might now or someday be exploitable. How
> are folks handling this. Have you revoked execute privileges from
> public from all packages, a certain set of packages (if so which ones)?
> Is there a list of packages which have the potential to be exploited.
> Revoking privileges can be tricky. Dba_dependencies will find calls
> from stored procedures, but not anonymous blocks.
>
>
>
> Ian MacGregor
> Stanford Linear Accelerator Center
> ian_at_slac.stanford.edu
>
>
>
>
>
>
>
>
>
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