Get the Whitepaper called Penetration from application down to OS – Getting OS access using Oracle Database unprivileged user.
You can download it from the following link: https://packetstormsecurity.com/files/download/76548/pfadto-oracle.pdf
Source: https://packetstormsecurity.com/files/76548/Whitepaper-OS-Access-Using-Oracle-Database-User.html