JPMorgan Chase, the largest US bank by market capitalizationfiles lawsuits against people who stole money from the bank after following the advice of a viral “money hack” which appeared on TikTok in late August.

This check-writing “hack” made the rounds on social media this summer, showing people that a bug in Chase’s system would allow them to write checks, deposit them at ATMs, and immediately withdraw that money.

“This ‘money hack’ wasn’t just bad advice, it was actually check fraud, which is a felony,” Alaina Fingal, money coach and member of CNET’s expert review board, shared in a recent story.

The problem in Chase’s system allowed customers to withdraw more money than they had in their bank accounts, essentially stealing from the bank. Chase quickly caught on and fixed the system problem.

Chase Bank now investigates thousands of cases of fraudulent activity, starting with the biggest offenders first, according to Reuters.

How much is he suing Chase for?

In most cases, the alleged perpetrators of this “hack” are sued for the amount they withdrew, and the lawsuits could lead to criminal charges. While these civil cases are separate from the criminal charges, Chase said it has referred the cases to law enforcement agencies.

Chase has filed lawsuits in three federal courts in Los Angeles, Houston and Miami, specifically accusing two people and two companies of using the system error to obtain more than $661,000, Reuters reported. The bank is still investigating thousands of cases of potential check fraud.

How to avoid “bad” money tips on TikTok

While there are certainly educational financial TikTok accounts you could take advantage of, the Chase Bank error underscores the need to have multiple sources of information. Fingal suggests doing your own research before following any money advice. This includes researching the financial advice as well as the account displaying the advice.

She cautions against taking online money advice from anyone without credentials, such as a certified financial planner (CFP), financial coach or certified public accountant (CPA).

You should be skeptical of any hack that offers “free money,” Fingal said. If a piece of advice sounds too good to be true, it probably is.