If you’re running a Windows Server 2003 machine, you have a problem. Your already-vulnerable computer is now at severe risk of being hacked.

That’s due to the internet release earlier this month of a batch of updates that  on computers running Windows Server 2003, according to security researchers.

“I can teach my mom how to use some of these exploits,” said Jake Williams, founder of Rendition Infosec, a security provider. “They are not very complicated at all.”

Experts are urging affected businesses to upgrade to the latest Windows OSes, which offer that can address the threat.

 to Shodan, a search engine for devices. But Williams estimates there are many more vulnerable machines running behind company firewalls.

So, for those that can’t, here are some tips to keep your old Windows Server 2003 machine secure.

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This can involve restricting access to your most critical servers, and ensuring only system admins can control them. “So instead of giving 20,000 people in a company access, you can cut that number down to 20,” Williams said.

Thus, if hackers ever do breach the firewall, they’ll have access to a smaller segment of the corporate network.

Network segmentation also doesn’t cost a lot of money. Enterprise internet routers often contain access control features that can limit which computers can talk to what, Williams said.

Businesses should also consider monitoring the vulnerable servers, or at least the ones carrying critical information. Any unusual data traffic moving through them is probably a sign they’ve been hacked, he said.

Weighing the risks

To keep malicious activity out of vulnerable systems, can also be used, said Jason Leitner, president of Below0Day, an IT security provider.

Whitelisting works by allowing only trusted applications to run on a computer. It’s the opposite approach of antivirus products, which essentially blacklists malicious programs based on known indicators.

Businesses can also create backups of any sensitive data stored in these machines. One malicious threat that’s been growing in recent years has been . It works by infecting a computer, and encrypting all the data inside. To free the machine, victims have to pay a ransom, usually in bitcoin.

However, even with these safeguards, the best solution to protecting a vulnerable Windows Server system is to upgrade, according to security experts.

Although it might be costly in the short-term, the investment can help businesses avoid a disastrous data breach. Tiago Henriques, CEO of security firm BinaryEdge, encourages businesses to calculate which is higher: “The cost of buying the upgrade or the damage to their brand and their clients if they get hacked?”