That lack of user interaction — or request for consent — is what confused and concerned some former Kaspersky customers.

The Russian cybersecurity company says it's been notifying users of the change and is aiming for a smooth transition of software.

Kaspersky's antivirus software deletes itself across the US and installs UltraAV instead without notifying customers. Some are frustrated and struggling to uninstall the new program.

After U.S. ban, Kaspersky's American customers were automatically migrated to UltraAV antivirus, in some cases without the customers' knowledge.

Kaspersky deleted its anti-malware software from computers across the United States and replaced it with UltraAV's antivirus solution without warning.

Kaspersky antivirus software automatically deletes itself from U.S. users' computers and installs UltraAV without warning.

Last week, users of Kaspersky anti-virus software found that the software had been uninstalled from their computers and that UltraAV's anti-virus had been installed in its place. The users had not consented to or initiated any of it.