The FBI has alerted parents to a new cyber threat to their children’s security: Synthetic Identity Theft.

This threat, which specifically targets children, is a sophisticated type of identity theft in which criminals use real social security numbers alongside fake information (names, birth dates, addresses, etc.) in order to establish new identities.

FBI Assistant Special Agent in Charge Steve Goldman said it’s happening a lot, with criminals using social security numbers belonging to children because “they haven’t been used before to establish credit.”

Criminals build the credit over time to maximize the available credit—“They take their time to make it look more legitimate,” says Goldman—which they can then use to make a large purchase, maxing out the credit line. This ultimately destroys the hacked person’s—or child’s—credit.

“It’s difficult once somebody starts using your social security number and your information to try and unwind that and get back to where that information only pertains to you,” he told KATU News.

What Parents Can Do to Stop this Threat

1. Limit how often you release your child’s social security number.

The more you release your child’s social security number, the more at risk s/he will be.

2. Check your child’s credit report.

Parents should go online to access and monitor their child’s credit report every single year. A free report is available annually online, by phone or mail. If your child does have a credit report, the FBI says it could be a sign of fraud.

3. Freeze your child’s accounts.

If parents do find their child has a credit report, if the child is under 15, parents can take action by freezing their child’s accounts. Teens who are 16 to 17 years of age will have to freeze and unfreeze their own accounts. Goldman says “It’s not difficult to lock down and freeze your credit and it’s not difficult to unfreeze it if you need to. Eventually, when it’s needed, it can be unlocked and then used for establishing credit.”