Security flaw in Florida tax website exposed filers’ sensitive data

Some Florida residents may be keeping a close eye on their finances after a security incident. Researcher Kamran Mohsin tells TechCrunch that Florida’s Department of Revenue website had a flaw that exposed hundreds of filers’ bank account and Social Security numbers. Anyone who logged in to the state business tax registration site could see, modify and even delete personal data just by modifying the web address pointing to a taxpayer’s application number — you just needed to change the digits in the link.

There were over 713,000 applications in the Department’s pipeline at the time of the discovery, Mohsin said. Mohsin warned the Department about the flaw on October 27th.

Department representative Bethany Wester said in a statement that the government fixed the flaw within four days of the report, and that two unnamed firms have deemed the site secure. She added there was “no sign” attackers abused the flaw, but didn’t say how officials might have spotted any misuse. The agency contacted every affected taxpayers by phone or writing within four days of learning about the issue, and has offered a year of free credit monitoring.

Bugs like these, known as insecure direct object references, are relatively easy to fix. The damage might also be limited compared to other tax-related breaches, such as a Healthcare.gov intrusion that compromised about 75,000 people in 2018. However, the incident underscores the potential harm from weak security — even a small-scale exposure like this could be used to commit tax fraud and steal refunds.