However a spokesOpera sang that it will have a limited impact. The attackers nicked at least one old and expired Opera code signing certificate, which they have used to sign some malware. This has allowed them to distribute malicious software which incorrectly appears to have been published by Opera Software, or appears to be the Opera browser.
However, Opera warned that it was possible that thousands of Windows users who were using the browser between 01.00 and 01.36 UTC on June 19th, may automatically have received and installed the malicious software. Opera plans to roll out a new version of its flagship browser which will use a new code signing certificate.