The researchers, Joshua Wright of the SANS Institute and Carlos Cid, of the University of London, said that the password algorithm Oracle uses is weak -- Oracle doesn't preserve the case of the password, for example -- and provides attackers several ways to break into databases.
"An adversary with limited resources can mount an attack that would reveal the plaintext password from the password hash for a known user," wrote Wright and Cid.
Although an attacker would have to have one of more usernames and the associated password hashes to proceed, that's not an impossible chore, even if the assault is only a brute force attack.
The pair used an off-the-shelf workstation powered by a Pentium 4 2.8GHz processor to test Oracle password hash cracking, then concluded that all the possible passwords of an account could be cranked out in under 40 days, giving 20 days as the average time it would take to break into an account.
"This is especially problematic for organizations with a password expiration duration that is shorter than 20 days, since it is likely an attacker will be able to produce the plaintext password before the account password is changed," wrote the researchers.
Among their recommendations, Wright and Cid advised Oracle-equipped enterprises to enforce longer passwords (12 characters minimum) and require that passwords be changed frequently.
"The SANS Institute contacted the Oracle product security team about these findings on 7/12/2005," said Johannes Ullrich, the chief research officer at the SANS Internet Storm Center, in an alert posted Thursday. "Subsequent requests for clarification on what Oracle plans to do to address these vulnerabilities have gone unanswered."
Oracle did not immediately respond to TechWeb's call for comment.