Sources said the agency officials have pin-pointed three Internet Protocol (IP) address -- a unique numerical label borne by each computer in a network that use worldwide web for communications -- two originated from Seattle, Pennsylvania in the US and other in Daugavpils, Latvia in northern Europe.
They said the agency has moved a local court here seeking permission to access authorities in the US and Latvia for collecting information on the IP addresses.
The CBI had on Dec 4 last year registered a case against unknown persons of "Pakistani Cyber Army" for hacking and defacement of its website under various Sections of Information Technology Act.
The website was unauthorisedly accessed and defaced in the intervening night of Dec 3 and 4, 2010.
According to the CBI, the IP addresses in the US has been linked to Amazon.com Inc. (Amazon Web Services) and Network Operations Center Inc whereas the third one is traced to DEACDCRIGAHOSTINGNET, Digitalas Ekonomikas Attistibas Centres 24 J. Riga in Latvia.
"We are investigating the matter. An application has been filed before the court to get access to authorities in the US and Europe to get information. We would send a team to trace hackers once we have the desired information," a senior CBI official said.
He said initially the CBI will seek details of network administrators and other technical information used to log in to the network used in hacking the CBI website.
The CBI had secured its website from the hackers after putting up more secure features on its portals in Jan.