A new malware campaign has emerged, targeting software developers with a stealthy backdoor named FogDoor. The attack, which began in March 2025, specifically targets Polish-speaking developers and job seekers. This sophisticated campaign uses fake coding challenges, such as the FizzBuzz test, to infiltrate systems. The attack starts with a GitHub repository hosting a malicious ISO file labeled “”Zadanie rekrutacyjne.iso,”” which contains a flawed JavaScript script and a malicious Windows shortcut.
Once executed, the shortcut triggers a PowerShell script that deploys FogDoor, allowing the attackers to gain persistent access.
The malware harvests sensitive data, including browser cookies and Wi-Fi credentials, and enables remote command execution. FogDoor operates uniquely by retrieving instructions from a social media profile and using ephemeral webhook services for data exfiltration, making it harder to track and shut down. Researchers from Cyble Research and Intelligence Labs (CRIL) identified the attack, noting that it specifically geofenced targets in Poland and nearby regions.
FogDoor’s infection process exploits the developer’s familiarity with coding exercises and common interview practices. Upon mounting the ISO file, victims encounter a defective script and a disguised documentation file. Running the malicious shortcut launches the PowerShell script, which deploys the malware and establishes persistence by creating a scheduled task that reactivates the malware every two minutes.
The malware further checks the victim’s location, terminating the execution if the target is outside Poland, ensuring a more targeted attack.
Once the malware is active, it accesses social media profiles for commands, which are executed to exfiltrate browser cookies, credentials, and Wi-Fi passwords. This data is then uploaded to a file-sharing service, with traces of the attack deleted to avoid detection. Cyble’s analysis underscores how FogDoor uses a combination of social engineering, geofencing, and ephemeral command-and-control channels to operate undetected. As the campaign evolves, experts recommend enhanced security training and behavioral analytics to detect and prevent such socially engineered threats.
