A BBC FTP server ftp.bbc.co.uk was compromised by a Russian hacker and access to it touted online, say computer security researchers.

The miscreant behind the attack on the internet-facing file store tried to sell access to the infiltrated system to other crims on Christmas Day, we're told. Hold Security – which this year has helped break news of data heists at Adobe and a top-flight limo company – spotted someone trying to sell access to ftp.bbc.co.uk, according to Reuters.

FTP is a 1970s vintage protocol for transferring information in bulk over the internet; its use is discouraged because usernames and passwords to log into accounts are sent over the network unencrypted, although there are ways to establish secure connections.

The hacked service was used by reporters to file material from the field, and by advertisers to upload video to BBC Worldwide channels. The invaded computer was cleaned up over the weekend.

Right now the system appears to be running ProFTPD 1.3.3g on Solaris, but there's nothing to indicate that was the vulnerable software. However, versions of ProFTPD prior to 1.3.3g suffer from a use-after-free bug (CVE-2011-4130) that allows an attacker to execute code remotely on the machine hosting the server; a flaw that's been known about since 2011.

"The only other information that I can offer is that the hacker was offering a screenshot proving that he had administrative access to the BBC server," Alex Holden, chief information security officer at Hold Security, told BBC News.

It is not clear how deep the hacker managed to penetrate Auntie: specifically, whether the miscreant obtained just an FTP admin account login, gained control of the user account running the FTP daemon, or gained full control of the machine running the file-transfer server. Don't forget, a compromised computer could have acted as a stepping stone to other systems within the Beeb's network.

Hold Security found no evidence anyone paid for access to the server. A spokesman for the BBC refused comment, although its news team published a report on the break-in. ®