Yesterday, there was an interesting article was posted/published On InfoWorld By Paul Venezia.
http://www.infoworld.com/d/security/fundamental-oracle-flaw-revealed-184163
http://www.infoworld.com/t/data-management/calling-all-oracle-customers-184103?source=fssr
Oracle has published this On Its MOS Bug 12371955 Backup task can cause increased SCN growth rate leading to ORA-600 [2252] errors with Document ID [ID 12371955.8] and Old existing Document 253977.1 will also give some information on it.
for this to be fixed , One should apply the latest CPU patch released on 18-Jan-2012 by Oracle.
Oracle has published an article on MOS yesterday: note 1376995.1 with an associated script “scnhealthcheck.sql” you can find and download in note 1393363.1.which are very helpful.
By Sriram Sanka 