Hidden Backdoor in CCleaner Security App Has Infected 2.3 Million People

Hidden Backdoor in CCleaner Security App Has Infected 2.3 Million People

Hackers have hidden a backdoor in a security application called CCleaner. So far it has 2 billion downloads and has infected 2.3 million people and counting.

Security researchers have discovered cyber criminals have installed a backdoor in a security application for PCs. Users of the Avast-owned CCleaners for Windows have been advised to update their software immediately.

Researchers at Cisco Talos discovered the threat on Sept. 13 after CCleaner 5.33 caused their systems to flag malicious activity. The company warned that the hack could be comparable to the NotPetya ransomware outbreak, which spread after a Ukrainian accounting app was infected.

The hacked application allows for download of further malware, such as ransomware or keyloggers, and there are fears that virtually billions could be impacted. The security app has 2 billion downloads and claims to be getting five million extra a week, making the threat even more severe.

The backdoor installed in the application would send encrypted information about the infected computer - the name of the computer, installed software and running processes - back to the hacker's server. The hackers also used what is known as a domain generation algorithm (DGA) whenever the criminal's server went down, the DGA could create new domains to receive and send stolen data. Researchers have noted that the use of a DGA shows that these hackers are very sophisticated.

Further investigation found that the CCleaner download server was hosting the backdoored app as far back as Sept. 11 and the affected version had been released on August 15. Which means for weeks the malware was spreading inside a supposedly-legitimate security software.

On Sept. 12, CCleaner released an untained version of the software, version 5.34.

Featured

  • AI Is Now the Leading Cybersecurity Concern for Security, IT Leaders

    Arctic Wolf recently published findings from its State of Cybersecurity: 2025 Trends Report, offering insights from a global survey of more than 1,200 senior IT and cybersecurity decision-makers across 15 countries. Conducted by Sapio Research, the report captures the realities, risks, and readiness strategies shaping the modern security landscape. Read Now

  • Analysis of AI Tools Shows 85 Percent Have Been Breached

    AI tools are becoming essential to modern work, but their fast, unmonitored adoption is creating a new kind of security risk. Recent surveys reveal a clear trend – employees are rapidly adopting consumer-facing AI tools without employer approval, IT oversight, or any clear security policies. According to Cybernews Business Digital Index, nearly 90% of analyzed AI tools have been exposed to data breaches, putting businesses at severe risk. Read Now

  • Software Vulnerabilities Surged 61 Percent in 2024, According to New Report

    Action1, a provider of autonomous endpoint management (AEM) solutions, today released its 2025 Software Vulnerability Ratings Report, revealing a 61% year-over-year surge in discovered software vulnerabilities and a 96% spike in exploited vulnerabilities throughout 2024, amid an increasingly aggressive threat landscape. Read Now

  • Motorola Solutions Named Official Safety Technology Supplier of the Ryder Cup through 2027

    Motorola Solutions has today been named the Official Safety Technology Supplier of the 2025 and 2027 Ryder Cup, professional golf’s renowned biennial team competition between the United States and Europe. Read Now

  • Evolving Cybersecurity Strategies

    Organizations are increasingly turning their attention to human-focused security approaches, as two out of three (68%) cybersecurity incidents involve people. Threat actors are shifting from targeting networks and systems to hacking humans via social engineering methods, living off human errors as their most prevalent attack vector. Whether manipulated or not, human cyber behavior is leveraged to gain backdoor access into systems. This mainly results from a lack of employee training and awareness about evolving attack techniques employed by malign actors. Read Now

New Products

  • AC Nio

    AC Nio

    Aiphone, a leading international manufacturer of intercom, access control, and emergency communication products, has introduced the AC Nio, its access control management software, an important addition to its new line of access control solutions.

  • HD2055 Modular Barricade

    Delta Scientific’s electric HD2055 modular shallow foundation barricade is tested to ASTM M50/P1 with negative penetration from the vehicle upon impact. With a shallow foundation of only 24 inches, the HD2055 can be installed without worrying about buried power lines and other below grade obstructions. The modular make-up of the barrier also allows you to cover wider roadways by adding additional modules to the system. The HD2055 boasts an Emergency Fast Operation of 1.5 seconds giving the guard ample time to deploy under a high threat situation.

  • Compact IP Video Intercom

    Viking’s X-205 Series of intercoms provide HD IP video and two-way voice communication - all wrapped up in an attractive compact chassis.