Extproc in Oracle 9i and 10g does not require authentication to load a library or execute a function, which allows local users to execute arbitrary commands as the Oracle user.
https://exchange.xforce.ibmcloud.com/vulnerabilities/18662
http://www.us-cert.gov/cas/techalerts/TA04-245A.html
http://www.securityfocus.com/bid/10871
http://www.ngssoftware.com/advisories/oracle23122004C.txt
http://www.kb.cert.org/vuls/id/316206
http://sunsolve.sun.com/search/document.do?assetkey=1-26-101782-1