Gloucester City Council has been hit with a 100,000 fine after a hacker downloaded 30,000 emails containing employees' personal information.
In July 2014, a hacker "took advantage of a weakness in the council's website" to gain direct access to the council's mailboxes, which stored information on employee finances as well as internal communications.
The attack exploited the highly publicised 'Heartbleed' flaw, a vulnerability within the OpenSSL software library that allowed hackers to eavesdrop on web users, as well as steal usernames, passwords, documents, and in this case, emails.
Despite the bug becoming widely-publicised in the media, as well as in warnings issued by UK data watchdog the Information Commissioner's Office (ICO), the council knowingly failed to fix the vulnerabilities, according to the regulator.
Sally Anne Poole, group enforcement manager at the ICO, described the incident as a "serious oversight", adding that the council's security systems were not robust enough to protect the data they held.
"The attack happened when the organisation was outsourcing their IT systems. A lack of oversight of this outsourcing, along with inadequate security measures on sensitive emails, left them vulnerable to an attack," she said.
"Business and organisations must understand they need to do everything they can to keep people's personal information safe and that includes being extra vigilant during periods of change or uncertainty," added Poole.
Jon McGinty, managing director at the council, said in a statement to IT Pro that the penalty would have a "serious and detrimental" impact on the authority's finances, and is considering appealing the decision.
"The council takes the security of its data very seriously and remains of the view that it did take swift and reasonable steps in 2014 to prevent a data breach as soon as it was alerted to the existence of this hacking vulnerability and the availability of a security patch," said McGinty.
"The council did account for the risk of this potential fine in its accounts for 2016-17, but nevertheless, its payment will only result in money being taken away from the people of Gloucester and given to the Treasury," added McGinty.
Paul Farrington, manager at application security company Veracode, said that the council could have done more to protect its data.
"The latest fine imposed by the ICO is an unfortunate outcome for this public body. Vendors like Veracode in 2014 were offering free scans, with no strings attached. The council officials could have protected the 30,000 leaked email records without incurring any additional cost burden."
The flaw, which was first discovered in 2014, was famously used against advice forum Mumsnet, which saw hackers post messages purportedly from CEO Justine Roberts that derided users and claimed the site was up for sale.
