The U.S. Federal Communications Commission (FCC) is asking for feedback on new proposed rules to crack down on SIM swapping and number port-out fraud, increasingly prevalent scams in which identity thieves hijack a target’s mobile phone number and use that to wrest control over the victim’s online identity.

In a long-overdue notice issued Sept. 30, the FCC said it plans to move quickly on requiring the mobile companies to adopt more secure methods of authenticating customers before redirecting their phone number to a new device or carrier.

“We have received numerous complaints from consumers who have suffered significant distress, inconvenience, and financial harm as a result of SIM swapping and port-out fraud,” the FCC wrote. “Because of the serious harms associated with SIM swap fraud, we believe that a speedy implementation is appropriate.”

The FCC said the proposal was in response to a flood of complaints to the agency and the U.S. Federal Trade Commission (FTC) about fraudulent SIM swapping and number port-out fraud. SIM swapping happens when the fraudsters trick or bribe an employee at a mobile phone store into transferring control of a target’s phone number to a device they control.

From there, the attackers can reset the password for almost any online account tied to that mobile number, because most online services still allow people to reset their passwords simply by clicking a link sent via SMS to the phone number on file.

Scammers commit number port-out fraud by posing as the target and requesting that their number be transferred to a different mobile provider (and to a device the attackers control).

The FCC said the carriers have traditionally sought to address both forms of phone number fraud by requiring static data about the customer that is no longer secret and has been exposed in a variety of places already — such as date of birth and Social Security number. By way of example, the commission pointed to the recent breach at T-Mobile that exposed this data on 40 million current, past and prospective customers.

What’s more, victims of SIM swapping and number port-out fraud are often the last to know about their victimization. The FCC said it plans to prohibit wireless carriers from allowing a SIM swap unless the carrier uses a secure method of authenticating its customer. Specifically, the commission proposes that carriers be required to verify a “pre-established password” with customers before making any changes to their accounts.

According to the FCC, several examples of pre-established passwords include:

-a one-time passcode sent via text message to the account phone number or a pre-registered backup number
-a one-time passcode sent via email to the email address associated with the account
-a passcode sent using a voice call to the account phone number or pre-registered back-up telephone number.

The commission said it was also considering updating its rules to require wireless carriers to develop procedures for responding to failed authentication attempts and to notify customers immediately of any requests for SIM changes.

Additionally, the FCC said it may impose additional customer service, training, and transparency requirements for the carriers, noting that too many customer service personnel at the wireless carriers lack training on how to assist customers who’ve had their phone numbers stolen.

The FCC said some of the consumer complaints it has received “describe wireless carrier customer service representatives and store employees who do not know how to address instances of fraudulent SIM swaps or port-outs, resulting in customers spending many hours on the phone and at retail stores trying to get resolution. Other consumers complain that their wireless carriers have refused to provide them with documentation related to the fraudulent SIM swaps, making it difficult for them to pursue claims with their financial institutions or law enforcement.”

“Several consumer complaints filed with the Commission allege that the wireless carrier’s store employees are involved in the fraud, or that carriers completed SIM swaps despite the customer having previously set a PIN or password on the account,” the commission continued.

Allison Nixon, an expert on SIM swapping attacks chief research officer with New York City-based cyber intelligence firm Unit221B, said any new authentication requirements will have to balance the legitimate use cases for customers requesting a new SIM card when their device is lost or stolen. A SIM card is the small, removable smart card that associates a mobile device to its carrier and phone number.

“Ultimately, any sort of static defense is only going to work in the short term,” Nixon said. “The use of SMS as a 2nd factor in itself is a static defense. And the criminals adapted and made the problem actually worse than the original problem it was designed to solve. The long term solution is that the system needs to be responsive to novel fraud schemes and adapt to it faster than the speed of legislation.”

Eager to weigh in on the FCC’s proposal? They want to hear from you. The electronic comment filing system is here, and the docket number for this proceeding is WC Docket No. 21-341.