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Interlock Ransomware Gang Deploys ClickFix Attacks to Breach Corporate Networks

 

Cybersecurity researchers have revealed that the Interlock ransomware gang has adopted a deceptive social engineering technique called ClickFix to infiltrate corporate networks. This method involves tricking users into executing malicious PowerShell commands under the guise of resolving system errors or completing identity verification steps, leading to the deployment of file-encrypting malware. 

While ClickFix attacks have previously been associated with ransomware campaigns, this marks the first confirmed use by Interlock, a ransomware operation that surfaced in late September 2024. The group targets both Windows systems and FreeBSD servers and maintains a dark web leak portal to pressure victims into paying ransoms that can reach millions of dollars. Interlock does not seem to operate as a ransomware-as-a-service (RaaS) model. 

According to Sekoia researchers, Interlock began using ClickFix tactics in January 2025. Attackers set up fake websites mimicking legitimate IT tools—such as Microsoft Teams and Advanced IP Scanner—to lure victims. These fake sites prompt users to click a “Fix it” button, which silently copies a malicious PowerShell script to the user’s clipboard. If run, the command downloads a 36MB PyInstaller payload that installs malware under the guise of a legitimate tool. 

Researchers found the malicious campaign hosted on spoofed domains like microsoft-msteams[.]com, microstteams[.]com, ecologilives[.]com, and advanceipscaner[.]com. Only the last domain led to the actual malware dropper disguised as Advanced IP Scanner. When users unknowingly run the script, a hidden PowerShell window executes actions such as system reconnaissance, persistence via Windows Registry, and data exfiltration. The attackers deploy a range of malware via command-and-control (C2) servers, including LummaStealer, BerserkStealer, keyloggers, and the Interlock RAT—a basic remote access trojan capable of dynamic configuration, file exfiltration, shell command execution, and DLL injection. 

Post-compromise, Interlock operators use stolen credentials to move laterally through networks via RDP, leveraging remote access tools like PuTTY, AnyDesk, and LogMeIn. Data is exfiltrated to Azure Blob Storage, after which the Windows variant of Interlock ransomware is scheduled to run daily at 8:00 PM—a redundancy tactic to ensure encryption if the initial payload fails. The gang’s ransom notes have also evolved, now placing emphasis on the legal and regulatory consequences of leaked data. 

ClickFix attacks are gaining popularity among various cybercriminal groups, with recent reports also linking them to North Korean state-sponsored actors like the Lazarus Group, who use similar tactics to target job seekers in the cryptocurrency sector.

Interlock Ransomware: New Threat Targeting FreeBSD Servers and Critical Infrastructure Worldwide

 

The Interlock ransomware operation, launched in late September 2024, is increasingly targeting organizations around the globe. Distinctly, this new threat employs an encryptor specifically designed to attack FreeBSD servers, a relatively uncommon tactic among ransomware groups.

Interlock has already affected six organizations and publicly leaked stolen data after ransoms went unpaid. One prominent victim, Wayne County in Michigan, experienced a cyberattack early in October, adding to the list of affected entities.

Details about Interlock remain limited, with early reports emerging from cybersecurity responder Simo in October. Simo's analysis noted a new backdoor associated with the ransomware, discovered during an investigation on VirusTotal.

Shortly after, MalwareHunterTeam identified a Linux ELF encryptor related to Interlock. Upon further examination, BleepingComputer confirmed that this executable was built specifically for FreeBSD 10.4, though attempts to execute it in a FreeBSD environment failed.

Although ransomware targeting Linux-based VMware ESXi servers is common, an encryptor for FreeBSD is rare. The now-defunct Hive ransomware, disrupted by the FBI in 2023, was the only other known operation with a FreeBSD encryptor.

Trend Micro researchers shared additional samples of the Interlock FreeBSD ELF encryptor and a Windows variant, noting that FreeBSD is often used in critical infrastructure. This likely makes it a strategic target for Interlock, as attacks on these systems can lead to significant service disruptions.

Trend Micro emphasizes that Interlock’s focus on FreeBSD infrastructure allows attackers to disrupt essential services and demand high ransoms, as these systems are integral to many organizations’ operations.

It is important to note that Interlock ransomware is unrelated to any cryptocurrency token of the same name.

While BleepingComputer encountered issues with running the FreeBSD encryptor, they successfully tested the Windows version, which performed actions like clearing event logs and deleting the main binary using rundll32.exe if self-deletion is enabled.

When encrypting files, Interlock appends the .interlock extension and generates a ransom note titled "!README!.txt" in each affected folder. The note explains the encryption, threats, and includes links to a Tor-based negotiation site where victims can communicate with the attackers. Each victim receives a unique ID and email for registration on this negotiation platform.

During attacks, Interlock breaches networks, steals sensitive data, and then deploys the encryptor to lock down files. The data theft supports a double-extortion scheme, with threats to leak data if ransoms—ranging from hundreds of thousands to millions of dollars—are not paid.