In a statement on Thursday, the company said the information that was attempted to be exfiltrated included names, email addresses and hashed passwords.
As to whether data had been stolen or not, the company had a bet each way, saying: "Though it is possible some of this information was removed from Dell’s network, our investigations found no conclusive evidence that any was extracted."
And it added: "Additionally, Dell cyber security measures are in place to limit the impact of any potential exposure.
"Credit card and other sensitive customer information was not targeted. The incident did not impact any Dell products or services."
Users of the site were advised to change their passwords the next time they logged in.
They were also told that if they used the same password on other sites, to also change them there.
Dell has set up a page where it will post updates on the incident, if required.