The Nitrogen ransomware campaign has been using deceptive malvertising techniques to target organizations. One method involved fake software downloads, such as a counterfeit “WinSCP” installer, which was spread through malicious ads on platforms like Bing. Users searching for “WinSCP download” were redirected from legitimate sources to compromised WordPress sites hosting malicious ZIP files. These files bundled a legitimate installer with a malicious DLL, which triggered DLL sideloading, installing the ransomware.
Once executed, the malicious DLL initiated a broader attack chain, deploying BlackCat ransomware on compromised systems. Further investigation revealed that Cobalt Strike, a post-exploitation framework, played a key role in maintaining persistence and facilitating lateral movement within networks. Suspicious executables like Intel64.exe and tcpp.exe were identified on infected systems, with Cobalt Strike configurations being flagged by security tools. These tools also exposed internal IP addresses and beacons, indicating active lateral movement within the targeted networks.
The attackers also used log-clearing techniques to hinder detection, specifically targeting Windows event logs and PowerShell logs.
However, forensic analysis of crash dumps and user access logs revealed key insights into the attack, showing evidence of Cobalt Strike activity. By using advanced tools like CyberChef and Velociraptor, investigators were able to parse encrypted configurations and track the attackers’ movements. YARA rules and memory analysis helped pinpoint malicious binaries, providing critical data for understanding the full scope of the attack.
The complexity of these attacks highlights the need for organizations to strengthen their defenses against malvertising and monitor for suspicious DLL loading. Advanced forensic techniques, including memory dump analysis and automated detection tools, are essential to uncovering threats like Nitrogen. As attackers continue to evolve their tactics, cybersecurity professionals are advised to stay vigilant and implement robust monitoring systems to mitigate the growing impact of ransomware campaigns.
