The city of Chicago on Friday said that employee emails were stolen in a Jones Day data breach during a data transfer to Accellion’s FTA file sharing service.
The cyber-attack was initially traced back to December 2020, when security researchers discovered a critical flaw in the 20-year-old large file transfer service that reached end-of-life on April 30, 2021. Approximately, 50 customers were still using FTA when the security incident took place, but only a few of them noticed significant data loss, Accellion claimed.
In February 2021, the major U.S.-based law firm Jones Day acknowledged that it was affected by the attack, after threat actors responsible for Clop ransomware published documents allegedly stolen from the company on their Tor-based website.
On Friday, the city of Chicago revealed that some employee emails that were given to Jones Day “as part of an independent inquiry being conducted by the firm” were compromised in the incident.
The data breach only impacted the Accellion FTA service and involved “emails sent or received from four former City employees over a two-year time period,” the city said.
Chicago officials notified the FBI and the Illinois Attorney General's office of the breach, which is usual in hacking incidents. While no documents have been released from the recent breach, the city warned residents that "hackers of government-related materials are known to manipulate and alter illegally obtained emails and documents.” However, it was unclear when the breach occurred and how many records were involved.
“The city of Chicago, the mayor’s office, and related agencies or departments will not respond to any media inquiries stemming from information obtained through illegal ransomware attacks. Reporting on materials compromised during a third-party vendor data transfer makes all of us less safe and encourages future bad actors to use nefarious means to gain information,” the city said in a statement.
Furthermore, the city says it was able to determine the number of impacted people and that it has already taken steps to inform the individuals who might have had personal information included in the compromised email files, either directly or through a notice on its website and a state-wide media alert.