A ransomware attack launched hours before the US Independence Day holiday weekend potentially affected 1,000 businesses, researchers said Saturday.

Information technology company Kaseya confirmed Friday that its "VSA" software -- used to manage and monitor computers remotely -- had been targeted but said it had limited the attack to "a very small percentage of our customers" who use the tools.

The software, however, was manipulated "to encrypt more than 1,000 companies," cybersecurity specialist Huntress Labs said on Saturday.