Nearly 15% of Android adware and malware cannot be removed, a new study by the world's leading anti-virus company has found.

According to Moscow-based cybersecurity firm Kaspersky, a significant number of mobile users have been affected over the past year by malware infections rooted in the Android system partition.

In a press release, Kaspersky explains that this type of attack "poses a high level of risk for users of infected devices because security solutions cannot access system directories and cannot delete malicious files."

The antivirus company stated that 14.8% of users who ran Kaspersky's Android antivirus app with an Android malware or adware attack in 2019 were unable to remove it as a result of the threat being installed in the system partition

The company also reported that it was unable to remove the threat from the system partition.

The company also found that 1% to 5% of its Android customers have encountered this type of unremovable adware, but for users of budget devices, that figure can reach 27%, as stated in a post on the tech-oriented SecureList blog.

This is because many Android devices come pre-installed with applications that cannot be removed, and adware and malware can hook into those permanent applications and gain a permanent foothold.

According to Kaspersky, cybercriminals use system partition infections to install adware on the devices of unsuspecting users and use two methods to infect devices.

"The threat gains root access to the device and installs adware on the system partition or code to display ads gets into the device's firmware before it is in the consumer's hands."

So what can be done? Prevention is the best course of action: it is these types of devices that are most likely to have adware and spyware pre-installed.

Also, installing and running the best Android antivirus apps will greatly improve your chances of stopping adware and malware before they infect your device. Don't rely on the built-in Google Play protection.

Unfortunately, if you end up with a phone that has adware installed before you purchase it, you are stuck with it.

"If a user purchases a device with such ads pre-installed, it is often impossible to remove them without risking damage to the system," states a Kaspersky blog post.

If your otherwise clean phone has become infected with System Partition adware, the next best thing to do is to wipe the device and reinstall the Android operating system. A factory reset will not work by itself.

Kaspersky's investigation detected a variety of malicious applications lurking in the system directory.

These include Trojans such as the Triada downloader, which "cannot be killed," those that can install and run applications without the user noticing, and "low threat" adware. In this blog, Kaspersky researchers detail at least 10 fairly new strains of malware and adware that are "unkillable" to varying degrees.

"In some cases, adware modules are pre-installed before the user receives the device, leading to potentially undesirable and unplanned consequences," the researchers explain.

"For example, many smartphones have features that provide remote access to devices. Such functionality, if abused, could lead to a data breach of the user's device."

Researchers explain that many smartphone manufacturers insert adware into their devices.

Some manufacturers allow users to stop or remove adware, but many do not. (Unfortunately, this is also true for some expensive phones.

Kaspersky researchers stated in a blog post that "users generally do not have the option of purchasing a device at the full price or at a slightly lower price with lifetime advertising."

"Our analysis shows that not only are mobile users regularly under attack from adware and other threats, but their devices may be compromised even before they are purchased," noted the Kaspersky press release.

"The Kaspersky press release states.

"We advise users to carefully examine the smartphone model they are about to purchase and consider these risks," said Igor Golovin of Kaspersky. . after all, it often comes down to a choice between a cheaper device or a more user-friendly one."