Council’s Data Breach from FOI Response

August 22, 2013

The Information Commissioner’s Office (ICO) has served Islington Council with a monetary penalty of £70,000 after personal details of over 2,000 residents were released online.

The information was inadvertently released in response to a freedom of information request, and revealed sensitive personal information relating to residents’ housing needs, including details of whether they had a history of mental illness or had been a victim of domestic abuse.

The freedom of information request had been made through the What Do They Know (WDTK) web site, which enables individuals to submit requests for information to public authorities. Responses are uploaded to the site and are available to all those wishing to view them.

The council released three spreadsheets on the 26 and 27 June that related to the work of the authorities’ Housing Performance Team. The council failed to spot that the documents contained the details of 2,375 residents who had either submitted applications for council housing or were council tenants.

These details were published on the WDTK website, and remained available until the 14 July when an administrator working for the site identified the error and removed the information. The web site reported the matter to the ICO two days later.

The ICO’s investigation found that the council had been alerted to the problem shortly after the first spreadsheet was published, but failed to correct the error. This resulted in the other two spreadsheets being released with the same problem.

ICO Head of Enforcement, Stephen Eckersley, said:

‘This mistake not only placed sensitive personal information relating to residents at risk, but also the highlighted the lack of training and expertise within the council. Councils are trusted with sensitive personal information, and residents are right to expect it to be handled in a proper way. Unfortunately, in this case that did not happen, and Islington Council must now explain to residents how it will stop these mistakes being repeated.’

The breach occurred due to a lack of understanding of pivot tables. These are used in Microsoft Excel and other spreadsheet programs to neatly summarise large amounts of data. But the tables retain a copy of the source data used. This information is hidden from view, but is easily accessible.

Islington Council used the tables to show statistics on how housing had been allocated to residents, but failed to remove the source data, and so sensitive personal data about tenants was revealed.

The ICO’s Head of Policy, Steve Wood, recently published a blog explaining the problems caused when public authorities fail to recognise the information retained in pivot tables. The ICO is currently investigating a number of other authorities that have also made similar errors.

There is an interesting blog post on this development here.