Car dealerships across the country are obliging use paper forms as the auto industry looks to recover from a cyberattack that caused massive disruption last week.

The attack hit CDK Global Systems, a cloud-based software that runs all the latest financials and information on car sales, financing, repairs, maintenance and more. The company serves approximately 15,000 car dealerships across the country.

Ford and Kia scored at statement to Reuters that some operations are affected.

Interfaces are said to have been hit with The back-to-back cyber attacks caused retailers to begin shutting down operations as early as Wednesday around 2 a.m. EST.

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for Bloombergthe group that claimed responsibility for the attack (which is believed to be based in Eastern Europe) demanded tens of millions of dollars in ransom to stop the hacking of the system before the weekend, which CDK was reportedly willing to pay.

“In the meantime, we are continuing to actively engage with our customers and offer them alternative ways of doing business,” CDK said. Reuters.

The software company is also planning to conduct an internal investigation and is cooperating with authorities as it works to fully restore its services nationwide.

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Restoration was underway until Monday afternoon, although CDK said it estimated the full restoration would take “days” rather than weeks to complete. However, he did not give an exact estimated time frame for when they will be able to resume business as usual.

CDK did not clarify exactly how many customers were still affected by the attack as of Monday afternoon.