FileFix is a recently identified variation of the ClickFix social engineering attack technique targeting Windows users. The attack manipulates victims into executing malicious code by pasting a crafted command into the Windows File Explorer address bar. Attackers typically initiate the attack via phishing emails directing users to counterfeit websites that simulate legitimate services but display error messages requiring an "environment check" or "diagnostic" step. Users are instructed to copy a displayed string, which appears to be a local file path, and paste it into the File Explorer address bar. However, the visible portion is only the tail end of a longer command string that includes leading spaces and a hidden malicious payload, often a PowerShell script launched via conhost.exe. This obfuscation leverages the limited visible space in the address bar to conceal the true command. Once executed, the PowerShell script can perform various malicious actions depending on user privileges and security controls. One documented technique involves "cache smuggling," where a JPEG file cached by the browser actually contains a malware archive that the script extracts and runs, enabling stealthy payload delivery without suspicious downloads or network activity. The attack is difficult to mitigate by blocking shortcuts or UI elements because the File Explorer address bar is a common and legitimate user interface element. Effective defense requires deploying advanced endpoint security solutions capable of detecting and blocking malicious script execution and maintaining robust user training programs to raise awareness of such social engineering tactics. The attack currently has no known exploits in the wild but represents a medium severity threat due to its potential impact and reliance on user interaction.

For European organizations, the FileFix attack poses a significant risk primarily through social engineering and stealthy malware delivery. Successful exploitation can lead to unauthorized code execution, potentially resulting in data breaches, ransomware deployment, or lateral movement within corporate networks. The stealthy nature of the attack, including cache smuggling and obfuscated command execution, can bypass traditional detection mechanisms, increasing the likelihood of prolonged undetected compromise. Organizations with less mature endpoint detection and response capabilities or insufficient user awareness programs are particularly vulnerable. The attack could disrupt business operations, compromise sensitive data, and damage organizational reputation. Given the reliance on phishing and user interaction, sectors with large numbers of office employees, such as finance, healthcare, and government, may face higher exposure. Additionally, the attack's ability to evade network-based detection by avoiding overt downloads or suspicious network requests complicates incident response and containment efforts.

1. Deploy advanced endpoint protection platforms with behavioral detection capabilities that can identify and block malicious PowerShell scripts and suspicious command executions, including those launched via conhost.exe. 2. Implement application control policies restricting the execution of unauthorized scripts and binaries, especially for users without administrative privileges. 3. Conduct targeted security awareness training emphasizing the risks of social engineering attacks like FileFix and ClickFix, focusing on recognizing phishing attempts and suspicious instructions involving system utilities. 4. Monitor and analyze endpoint logs for unusual File Explorer address bar usage patterns or unexpected PowerShell activity. 5. Employ network security solutions capable of detecting anomalous behavior despite the lack of overt downloads, such as monitoring for unusual cache or file extraction activities. 6. Enforce the principle of least privilege to limit the potential impact of malicious code execution. 7. Regularly update and patch all systems to reduce the attack surface and ensure security solutions are current. 8. Consider implementing technical controls to restrict or audit the use of clipboard operations involving system commands, where feasible, without disrupting legitimate workflows.