Toyota Motor Corp. said Wednesday some of its Japanese website content had been tampered with through a cyberattack that could have exposed visitors to a malicious program.

The automaker said it has not confirmed any leak of customer information. Toyota has found that someone illegally accessed the website and is investigating how the tampering occurred.

According to Toyota, the website may have been tampered with sometime between 6:26 p.m. on June 5 and 9:47 p.m. on June 14. Toyota is asking users who viewed the affected contents during that period to check using security software whether their PCs are infected with a virus and remove it if infected.