Iran has been blamed for the brute-force attack on UK Parliament earlier this year.
An unpublished assessment by British intelligence obtained by The Times fingers Iran for the high-profile hack. The revelation comes as the US president has refused to continue signing off the 2015 Iran nuclear deal, to which the UK is a party.
An estimated 90 email accounts were compromised on the Parliamentary network last May, as previously reported. Hackers attempted to gain access to accounts protected only by weak passwords. Two-factor authentication technology, widely used across the enterprise world for years, was not deployed at the time.
The Parliamentary digital services team has reportedly since made changes to lock out hackers. A spokesman in the House of lord press office told The Register that he wasn't able to comment on security issues. The House of Commons press team couldn't be reached on Monday afternoon.
Initial suspicion fell on Russia, but this theory has since been discounted. The evidence so far collected in the ongoing investigation includes "digital footprints" associated with Iran's Islamic Revolutionary Guard Corps. An investigation by the National Cyber Security Centre (NCSC) and the National Crime Agency continues, The Times reports.
Hackers tried to break into Scottish Parliament email accounts in August, weeks after similar campaigns against Westminster. First indications were that this assault was unsuccessful. El Reg has asked whether the attacks are believed to be linked but we're yet to hear back from our sources. We'll update this story as and when we hear more. ®