Storm-0249 Abuses EDR DLL Sideloading for Stealthy Ransomware Access
Storm-0249, previously known for mass phishing campaigns, has evolved into a sophisticated initial access broker employing advanced evasion techniques. The group now leverages legitimate, digitally signed files associated with endpoint detection and response (EDR) tools—such as SentinelOne—by abusing DLL sideloading to establish persistent, covert access within targeted networks. This method allows Storm-0249 to remain undetected for extended periods, conduct reconnaissance, and prepare for ransomware deployment, often selling this pre-staged access to ransomware-as-a-service affiliates. The attack chain typically begins with social engineering tactics like ClickFix, which manipulates users into executing malicious commands, followed by the deployment of malicious MSI packages with system-level privileges.
Security researchers have highlighted the growing trend among initial access brokers to adopt such stealthy post-exploitation techniques, which accelerate attack timelines and lower technical barriers for downstream threat actors. The abuse of trusted EDR processes through DLL sideloading is particularly concerning, as it exploits the inherent trust in security software to cloak malicious activity and facilitate ransomware operations. Organizations are urged to monitor for unusual activity involving EDR processes and to scrutinize the integrity of signed executables within their environments.
Timeline
Dec 15, 2025
Storm-0249 abuses EDR DLL sideloading to hide ransomware access
Researchers reported that Storm-0249 was abusing trusted EDR-related processes, including SentinelOne-associated signed files, through DLL sideloading to evade detection and maintain persistence. The technique was used to cloak post-exploitation activity and prepare access that could be sold to ransomware operators.
Dec 15, 2025
Storm-0249 observed using ClickFix and malicious MSI for initial access
Storm-0249 was reported using social engineering via the ClickFix technique to trick users into running malicious commands, followed by deployment of malicious MSI packages with system-level privileges. This reflects the group's evolution from mass phishing into a more sophisticated initial access operation.
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Storm-0249 Uses EDR Abuse and ClickFix for Stealthy Ransomware Deployment
Storm-0249, an initial access broker previously known for selling access to compromised networks, has adopted advanced techniques to facilitate ransomware attacks. The group now leverages social engineering tactics such as ClickFix, which tricks users into executing malicious commands via the Windows Run dialog. These commands use legitimate utilities like `curl.exe` to download and execute fileless PowerShell scripts from spoofed Microsoft domains, ultimately deploying malicious MSI packages with SYSTEM privileges. The attack chain includes DLL sideloading, where a trojanized DLL is placed alongside legitimate EDR components (notably SentinelOne's `SentinelAgentWorker.exe`), allowing the attacker's code to run within trusted processes and evade detection. Once persistence is established, Storm-0249 abuses EDR tools to collect system information and maintain stealthy access, making detection and remediation challenging for defenders. This evolution in Storm-0249's tactics demonstrates a shift from mass phishing to highly targeted, stealthy operations that exploit trusted security software for malicious purposes. The abuse of EDR solutions not only enables the bypassing of traditional security controls but also provides a reliable foothold for ransomware deployment. Security researchers recommend implementing robust email filtering, monitoring for unusual use of legitimate utilities, and updating detection rules to identify these advanced techniques. Organizations are urged to review their EDR configurations and monitor for signs of DLL sideloading and unauthorized PowerShell activity to mitigate the risk posed by this threat actor.
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