If you have an Android phone that's overcrowded with apps, now is a good time do some urgent spring cleaning. Cyber experts say they recently discovered a swathe of applications that have the vicious "Vapor" bug hidden inside them. Once installed, this nasty malware sets about attacking devices, displaying annoying adware whilst also trying to steal credit card data.

The worrying threat was first spotted by the team at IAS Threat Lab who say they began noticing "Vapor" attacks last year. It's now thought that hundreds of applications have been infected with over 60 million people installing them onto their phones.

"The IAS Threat Lab has uncovered an extensive and sophisticated ad fraud scheme, codenamed Vapor, that leverages fake Android apps to deploy endless, intrusive full-screen interstitial video ads," IAS explained.

"Vapor exploits unsuspecting users and ad networks on a massive scale, representing a highly organized and pervasive ad fraud scheme."

Security experts at Bitdefender have also noticed the "Vapor" bug. The cyber security firm says it has spotted a total of 331 worrying apps including QR Scanners, fitness services, diaries and battery optimisers.

"The apps display out-of-context ads and even try to persuade victims to give away credentials and credit card information in phishing attacks," Bitdefender warned.

Since being told of the attack, Google has now blocked all of the software discovered on its platform. That's good news but those who have downloaded any of the apps in question still need to be on red alert as the Google ban won't delete the apps from devices.

A full list can be found here, but Bitdefender and IAS have also revealed some of the worst offenders that have been installed the most. If you think you may have installed one of these apps, delete them now.

AquaTracker – Downloaded 1 million times

ClickSave Downloader – Downloaded 1 million times

Scan Hawk – Downloaded 1 million times

Water Time Tracker – Downloaded 1 million times

Be More – Downloaded 1 million times

BeatWatch – Downloaded 500,000 times

TranslateScan – Downloaded 100,000 times

Handset Locator – Downloaded 50,000 times

As always, whenever installing new applications, take time to read the reviews and make sure the developer is reputable.

If you have any concerns, DON'T tap the download button.

Although Google is now blocking more dodgy applications from getting onto its Play Store, some are clearly still slipping through the net.

That's why it's vital to keep an eye on your device and take care of it whenever you install anything new.