You probably thought that downloading the PC clean up tool CCleaner would keep your hard drive clean and your Windows PC working smoothly.
However, security experts have discovered that the popular tool has been infiltrated by hackers who have planted a form of malware into the software that can steal user data for shady purposes.
The hack was discovered by Piriform, the British firm which makes CCleaner, who revealed all in a rather alarming blog post.
The hack affects two of the firm’s most popular products: CCleaner and CCleaner Cloud.
While the firm says it has already issued a patch for CCleaner Cloud, users running CCleaner need to make sure they install the latest security update immediately.
Dubbed as “the number-one tool for cleaning your PC,” CCleaner is a tool that works to optimise your Windows PC, removing temporary files, browser data and other junk that may slow your computer down.
CCleaner is available as free or paid for subscription and both versions are said to have been affected by the breach.
Cybersecurity firm Avast, which recently bought Piriform estimates that 2.27 million people are affected by the hack. However, those running 32 bit versions of Windows are most at risk, as are those that run the free version of the software.
This is because the free version does not include automatic updates, meaning a significant number of users may be unaware they are still running a compromised version.
Piriform have said that CCleaner version 5.33.6162 on 32 bit Windows were compromised by the hackers.
The advice to users is to download the latest version immediately.
Piriform says that users must now ensure they are using CCleaner version 5.34 or higher, which can be downloaded here.