How To Remove CCleaner Malware – An In-Depth Guide

As a cloud data security expert with over a decade of experience, I‘ve seen many types of malware attacks. But few have been as worrisome as the CCleaner compromises. CCleaner is a popular utility used by over 2 billion people worldwide to clean unwanted junk from their computers. But faulty security practices allowed hackers to turn this helpful tool into a Trojan horse for installing malicious software onto users‘ systems.

In this guide, I‘ll provide an in-depth look at CCleaner‘s malware incidents based on my research and experience in the field. I‘ll explain what malware was installed, who was impacted, and most importantly, how to thoroughly remove infections and prevent future attacks.

What is CCleaner?

First, let‘s start with some background. CCleaner is a utility program from Piriform that allows users to delete unnecessary files and browser data like cookies, caches, download histories, etc. It provides an easy way to free up disk space and protect privacy by erasing tracking files.

Piriform made CCleaner available as a free download in 2004. Its ease of use, advanced features like registry cleaning, and ability to optimize system performance quickly made it a favorite among Windows users. In 2017, Piriform was acquired by the antivirus firm Avast.

At its peak, CCleaner boasted over 2 billion total downloads. Even with the malware incidents, it still enjoys a user base in the hundreds of millions. Many people still value its junk cleaning capabilities.

When and How CCleaner Was Infected

CCleaner‘s widespread popularity made it an enticing target for hackers:

• August 2017 – CCleaner version 5.33.6162 was infected with malware during development before release. Specifically, the 32-bit Windows version contained malware.

• January 2019 – Another attack inserted malware into the CCleaner 5.52 build for 32-bit systems.

In both cases, hackers infiltrated Piriform/Avast‘s internal networks and development tools to inject malware into the code base before the updates were signed and distributed.

The payloads were not detected until after the updates were live. Piriform estimates over 2.27 million users downloaded the infected August 2017 version before it was removed. The 2019 version had a much smaller reach.

Malware Installed by CCleaner

The CCleaner malware installed two main threats onto compromised computers:

• Floxif – Data gathering spyware that profiled a system‘s running processes, installed services, and active internet connections.

• Trojan.Nyetya – Functioned as a backdoor trojan, allowing hackers remote access to execute commands. It mainly targeted password theft, capturing keystrokes and browser data entered on infected machines.

In the 2017 attack, Floxif helped the hackers map out target systems and identify valuable data to steal. Meanwhile, Trojan.Nyetya quietly stole passwords, financial information, and other sensitive data in the background.

Together, this provided access to personal information while also allowing the attackers to pivot deeper into company networks for cyber espionage. The attackers remain unidentified but are suspected to be an advanced persistent threat (APT) group backed by a nation-state.

Warning Signs of Infection

How can you tell if your system was impacted by the CCleaner malware? Here are some signs to watch out for:

• CCleaner running sluggishly or freezing
• Antivirus program detecting Trojan.Nyetya
• System changes like new unknown processes in Task Manager
• Suspicious network traffic
• Passwords or accounts compromised

However, one of the most dangerous aspects of CCleaner‘s malware is that it was designed to operate silently in the background. A sophisticated observer could leverage the Floxif spyware to learn about a system while Trojan.Nyetya quietly stole passwords in the background – all without obvious symptoms.

So even if your computer seems fine, you should still check for infections if you used the compromised CCleaner versions.

Step 1: Verify Your CCleaner Version

First, you‘ll want to check whether you have a compromised CCleaner version installed. As a reminder, the known infected versions are:

• 5.33.6162 (August 2017)
• 5.52.6967 (January 2019)
• Any 32-bit Windows version

Here‘s how to check your version on Windows:

1. Open CCleaner
2. Look at the upper left corner of the window, next to the logo
3. Verify the version number displayed there

If you have one of the above versions, you may be compromised. Even if your version is older or newer, it‘s smart to scan your system.

On macOS, check under CCleaner in your Applications list. You can also right click the app and choose "Get Info" to see the version.

Versions of CCleaner after 5.46.6610 are confirmed as clean. But checking never hurts.

Step 2: Conduct Antivirus Scans

If you find you have a compromised CCleaner version, the next step is to scan for malware.

First, uninstall CCleaner to eliminate the source of infection. On Windows, you can uninstall programs through Settings. On Mac, drag the app to the Trash.

Next, run a full antivirus scan. Make sure your antivirus software is updated to the latest definitions before scanning. Settings like rootkit scanning and scanning for inactive malware can help detect dormant threats.

Here are some of the top antivirus programs to consider:

• Bitdefender – Provides excellent protection against malware and cyber threats. I recommend Bitdefender‘s GravityZone cloud-based endpoint security which leverages global threat intelligence to stop attacks.

• Webroot – Uses lightweight, cloud-based scans to quickly identify threats. Minimizes system impact during scans.

• Malwarebytes – Specializes in combating advanced malware, ransomware, and exploits that may evade traditional antivirus.

• ESET NOD32 – Strong heuristics analysis to detect malware by behavior, even if not yet catalogued in definitions.

Schedule regular antivirus scans going forward to catch future threats. I recommend cloud-based antivirus solutions that can quickly adapt to new threats based on data from millions of endpoints.

On-demand cloud scanning provides a huge advantage compared to traditional, signature-based antivirus software.

Step 3: Eliminate Any Remaining Malware

Unfortunately, traces of malware may still remain even after antivirus scanning. The CCleaner payload included advanced stealth capabilities designed to hide from security tools.

Here are some tips for removing leftover threats:

• Use multiple malware removal tools – Try tools like Malwarebytes, HitmanPro, or Emsisoft Emergency Kit which use different scanning methods than traditional antivirus.

• Check suspicious files and processes – Review unknown .dll, .exe and .sys files in your C:\ProgramData or AppData\Local folders. Terminate suspicious processes in Task Manager.

• Inspect registry – Use a registry cleaner/editor to check for malicious entries. Be careful modifying the registry.

• Reset browser – Uninstall browsers completely, delete all files/folders, reinstall fresh copies. This wipes any modified settings.

• Boot into Safe Mode – Helps remove malware that only runs at system startup or login. Then scan again.

For stubborn infections, the nuclear option is completely wiping your hard drive and reinstalling Windows. Backup your personal files first.

Step 4: Restore Settings & Passwords

Once the malware is removed, take these steps to further clean up and protect your accounts:

• Reset all account passwords – Any passwords captured by the CCleaner keylogger could be compromised. Generate new secure passwords for all important accounts, at least 15 characters long.

• Enable two-factor authentication (2FA) – Add an extra layer of security by requiring a code from your phone or authentication app when you login. This prevents unauthorized logins even if your password is compromised.

• Remove unauthorized browser extensions – Check for any new, unknown extensions installed and remove them. These may be used to monitor web activity or redirect traffic.

• Update software – Install the latest updates for your operating system, browsers, apps, drivers, etc. Hackers exploit vulnerabilities in outdated software.

• Use a password manager – This lets you use long, randomized passwords without having to remember them all. Consider 1Password, LastPass, or Dashlane.

Protecting Yourself Going Forward

While you can remove CCleaner‘s malware, it‘s important to take steps to prevent future infections:

• Use trusted security software – Stick to reputable, vetted programs from major vendors like Bitdefender, Malwarebytes, etc. Avoid unknown free antivirus tools which are often malware.

• Avoid pirated or cracked software – Cracked programs disable security checks and often contain malware payloads. Stick to legal software from authorized sellers.

• Install software updates quickly – Patches fix security flaws that could be exploited by hackers. Turn on automatic updates where possible.

• Use strong passwords and 2FA – Weak reused passwords make life easy for attackers. Follow best practices like using a password manager.

• Regularly backup your data – Ransomware and other malware can encrypt or delete your files. Backups let you restore data if disaster strikes.

• Watch out for phishing sites/emails – Many malware attacks start with social engineering to trick you into downloading fakes anti-virus tools or other malware trojans.

The CCleaner incident highlights how even reputable apps can sometimes be hijacked to distribute malware. But with proper precautions, you can avoid becoming a victim and keep your data safe. As threats evolve, lean on cloud-based security providers to protect against rapidly evolving attacks. With the right tools and know-how, you can confidently use your devices without worrying about malicious software.