In early June, cybersecurity researchers discovered that a compromised version of the Israel-based Hola Browser for Windows (version 1.251.91.0) was secretly downloading a Monero crypto miner to users’ devices. Shortly after the discovery, Hola confirmed that it had fallen victim to a supply chain attack. In this article, we break down how the attack went down, how the crypto miner works, and what it means for affected users.

What is Hola Browser, and how was the malware discovered?

The Israeli company Hola is best known for its VPN service, which users primarily rely on to bypass geo-restrictions and access region-locked content. In addition to the VPN, the company develops Hola Browser — a Chromium-based browser that comes with built-in VPN and proxy features.

Researchers first spotted signs of trouble during a standard compliance check for the AppEsteem Windows Certified Application program. As part of this certification process, independent cybersecurity firms audit software to ensure it only contains the components it claims to have and is free of unwanted or malicious features. Even after a certificate is granted, apps are regularly re-evaluated to ensure they continue to meet AppEsteem’s strict guidelines.

It was during one of these routine follow-up checks that experts noticed an unauthorized file bundling itself with version 1.251.91.0 of Hola Browser for Windows. Once installed, the file saved itself to the hard drive at C:\Program Files\Hola\me{.}exe. The file immediately raised red flags for researchers due to a laundry list of suspicious characteristics: it wasn’t on the list of approved application files, lacked a timestamp, and had no digital signature. On top of that, its code was heavily obfuscated, and it possessed the ability to inject itself directly into system memory.

Interestingly, researchers noted that the file didn’t show up in every single installation. Because the infection wasn’t widespread across all users, experts suspected early on that a specific stage in the Hola Browser distribution pipeline had been compromised. Hola later confirmed this theory, admitting it had fallen victim to a supply chain attack.

As for the suspicious me{.}exe file itself, closer analysis revealed that it was a stealthy crypto miner configured to mine Monero. We’ll now dive into the technical details of how it works.

How did attackers use Hola Browser to mine Monero?

Crypto miners are programs that harness a computer’s processing power to mine cryptocurrency. While some users install this software intentionally to generate a bit of income, miners that run on a machine without the owner’s knowledge are typically classified as unwanted.

Running a hidden miner can noticeably slow down the device, spike the user’s electricity bill, and shorten the hardware’s lifespan. That being said, it’s worth noting that a crypto miner infection will not actually steal the owner’s cryptocurrency; the damage is strictly limited to the hijackers leeching your computer’s hardware resources to line their own pockets.

As we mentioned above, the malicious download bundled with Hola Browser sneaked a Monero crypto miner onto victims’ devices. Launched in 2014 and built on the CryptoNote protocol, Monero currently trades at around US$330 per coin.

Compared to heavyweights like Bitcoin or Ethereum, Monero is a bit exotic and lesser-known to the general public. This niche status shows in its relatively modest price growth and smaller market capitalization — which is roughly 200 times lower than Bitcoin’s. However, Monero has one defining feature: privacy. While Bitcoin and Ethereum operate on fully transparent, public blockchains, where anyone can trace transactions, Monero is a “privacy coin”. It uses advanced cryptographic mechanisms to mask the sender, receiver, and transaction amounts. This extreme anonymity is exactly why hackers love hidden Monero miners — it makes it difficult for law enforcement and cybersecurity professionals to follow the money trail.

Additionally, Monero’s underlying algorithm is explicitly designed to mine efficiently using standard computer processors (CPUs). This stands in stark contrast to many other popular cryptocurrencies, which require specialized ASIC hardware or high-end graphics cards (GPUs) to be profitable.

But let’s look closer at how this played out with Hola Browser. When researchers dissected the malicious me{.}exe code, they found it was automatically adding its own files to the Microsoft Defender exclusion list. By allowlisting itself, the malware successfully blinded Windows’ built-in antivirus, allowing the crypto miner to run in the background completely unhindered.

Once inside, the program made a copy of itself under the name HolaMonitorService{.}exe, and set up a persistent Windows background service called hola_monitor_svc. This maneuver allowed the malware to entrench itself in the system, automatically launching every time the computer restarted. To avoid raising any red flags with sudden massive performance drops, the miner was programmed to stay dormant, kicking into gear only when the computer was idle.

How to protect your device from crypto miners and malware

To their credit, Hola’s development team responded swiftly to the initial reports of the suspicious file. They confirmed the supply chain breach, but stated that the incident only impacted 0.1% of their user base. The company has since tightened up security around its update distribution pipeline to guarantee that users only receive approved, certified, and digitally-signed software components moving forward.

In light of this incident, we highly recommend that all Hola Browser users update to the latest version immediately — especially those running the application on Windows.

More broadly, this situation is a textbook reminder of why it’s so critical to keep all your software up to date and run a robust cybersecurity solution on all your gadgets. For instance, Kaspersky Premium provides real-time alerts about suspicious software behavior and blocks threats instantly. As an added bonus, a Kaspersky Premium subscription includes a secure and reliable VPN.

Don’t forget that malicious crypto miners don’t just target PCs; they also go after smartphones, often disguising themselves as anything from popular mobile games to official government service apps. Check out our previous posts to learn more:

• Android Trojan posing as government services and Starlink apps
• What happens if you download a cracked program?
• Miner inconvenience: how cybercriminals blackmail YouTubers into promoting malware
• Mario Forever, malware too: a free game with a miner and Trojans inside

To achieve their malign aims, Android malware developers have to address several challenges in a row: trick users to get inside their smartphones, dodge security software, talk victims into granting various system permissions, keep away from built-in battery optimizers that kill resource hogs, and, after all that, make sure their malware actually turns a profit. The creators of the BeatBanker — an Android‑based malware campaign recently discovered by our experts — have come up with something new for each one of these steps. The attack is (for now) aimed at Brazilian users, but the developers’ ambitions will almost certainly push them toward international expansion, so it’s worth staying on guard and studying the threat actor’s tricks. You can find a full technical analysis of the malware on Securelist.

How BeatBanker infiltrates a smartphone

The malware is distributed through specially crafted phishing pages that mimic the Google Play Store. A page that’s easily mistaken for the official app marketplace invites users to download a seemingly useful app. In one campaign, the trojan disguised itself as the Brazilian government services app, INSS Reembolso; in another, it posed as the Starlink app.

The malicious site cupomgratisfood{.}shop does an excellent job imitating an app store. It’s just unclear why the fake INSS Reembolso appears all of three times. To be extra sure, perhaps?!

The installation takes place in several stages to avoid requesting too many permissions at once and to further lull the victim’s vigilance. After the first app is downloaded and launched, it displays an interface that also resembles Google Play and simulates an update for the decoy app — requesting the user’s permission to install apps, which doesn’t look out-of-the-ordinary in context. If you grant this permission, the malware downloads additional malicious modules to your smartphone.

After installation, the trojan simulates a decoy app update via Google Play by requesting permission to install applications while downloading additional malicious modules in the process

All components of the trojan are encrypted. Before decrypting and proceeding to the next stages of infection, it checks to ensure it’s on a real smartphone and in the target country. BeatBanker immediately terminates its own process if it finds any discrepancies or detects that it’s running in emulated or analysis environments. This complicates dynamic analysis of the malware. Incidentally, the fake update downloader injects modules directly into RAM to avoid creating files on the smartphone that would be visible to security software.

All these tricks are nothing new and frequently used in complex malware for desktop computers. However, for smartphones, such sophistication is still a rarity, and not every security tool will spot it. Users of Kaspersky products are protected from this threat.

Playing audio as a shield

Once established on the smartphone, BeatBanker downloads a module for mining Monero cryptocurrency. The authors were very concerned that the smartphone’s aggressive battery optimization systems might shut down the miner, so they came up with a trick: playing an all-but-inaudible sound at all times. Power consumption control systems typically spare apps that are playing audio or video to avoid cutting off background music or podcast players. In this way, the malware can run continuously. Additionally, it displays a persistent notification in the status bar, asking the user to keep the phone on for a system update.

Example of a persistent system update notification from another malicious app masquerading as the Starlink app

Control via Google

To manage the trojan, the authors leverage Google’s legitimate Firebase Cloud Messaging (FCM) — a system for receiving notifications and sending data from a smartphone. This feature is available to all apps and it’s the most popular method for sending and receiving data. Thanks to FCM, attackers can monitor the device’s status and change its settings as needed.

Nothing bad happens for a while after the malware is installed: the attackers wait it out. Then they trigger the miner, but they’re careful to throttle it back if the phone overheats, the battery starts dipping, or the owner happens to be using the device. All of this is handled via FCM.

Theft and espionage

In addition to the crypto miner, BeatBanker installs extra modules to spy on the user and rob them at the right moment. The spyware module requests Accessibility Services permission, and if this is granted, begins monitoring everything that’s happening on the smartphone.

If the owner opens the Binance or Trust Wallet app to send USDT, the malware overlays a fake screen on top of the wallet interface, effectively swapping the recipient’s address for its own. All transfers go to the attackers.

The trojan features an advanced remote control system and is capable of executing many other commands:

• Intercepting one-time codes from Google Authenticator
• Recording audio from the microphone
• Streaming the screen in real-time
• Monitoring the clipboard and intercept keystrokes
• Sending SMS messages
• Simulating taps on specific areas of the screen and text input according to a script sent by the attacker, and much more

All of this makes it possible to rob the victim when they use any other banking or payment services — not just crypto payments.

Sometimes victims are infected with a different module for espionage and remote smartphone control — the BTMOB remote access trojan. Its malicious capabilities are even broader, including:

• Automatic acquisition of certain permissions on Android 13–15
• Continuous geolocation tracking
• Access to the front and rear cameras
• Obtaining PIN codes and passwords for screen unlocking
• Capturing keyboard input

How to protect yourself from BeatBanker

Cybercriminals are constantly refining their attacks and coming up with new ways to profit from their victims. Despite this, you can protect yourself by following a few simple precautions:

• Download apps from official sources only, such as Google Play or the app store preinstalled by the vendor. If you find an app while searching the internet, don’t open it via a link from your browser; instead, head to the Google Play app or another branded store on your smartphone to search for it there. While you’re at it, check the number of downloads, the app’s age, and look at the ratings and reviews. Avoid new apps, apps with low ratings, and those with a small number of downloads.
• Check any permissions you grant. Don’t grant permissions if you’re not sure what they do or why that specific app requires them. Be extra careful with permissions like Install unknown apps, Accessibility, Superuser, and Display over other apps. We’ve written about these in detail in a separate article.
• Equip your device with a comprehensive anti-malware solution. We, naturally, recommend Kaspersky for Android. Users of Kaspersky products are protected from BeatBanker — detected with the verdicts HEUR:Trojan-Dropper.AndroidOS.BeatBanker and HEUR:Trojan-Dropper.AndroidOS.Banker.*.
• Regularly update both your operating system and security software. For Kaspersky for Android, which is currently unavailable on Google Play, please review our detailed instructions on installing and updating the app.

Threats to Android users have been going through the roof lately. Check out our other posts on the most relevant and widespread Android attacks and tips for keeping you and your loved ones safe:

• The perfect storm of Android threats
• Brain drain: vulnerabilities in mental health apps
• Pixnapping vulnerability: unblockable screenshots of your Android phone
• NFC skimming attacks
• A new layer of anti-phishing security in Kaspersky for Android