The LockBit ransomware group employs advanced tactics centered around DLL sideloading and masquerading to infiltrate and compromise target systems. DLL sideloading is a technique where attackers place malicious DLL files alongside legitimate applications, tricking these trusted programs into loading the malicious DLLs instead of the authentic ones. This abuse of the Windows DLL search order allows attackers to execute arbitrary code under the guise of legitimate processes, thereby evading traditional detection mechanisms. Masquerading tactics further enhance stealth by renaming malicious files to resemble legitimate system files, spoofing process names, and using authentic icons to blend into the operating system environment. Recent LockBit campaigns have exploited trusted executables such as Jarsigner.exe, MpCmdRun.exe, and Clink_x86.exe to facilitate the loading of malicious DLLs. The attack lifecycle is comprehensive, beginning with initial access, followed by privilege escalation, system discovery, credential theft, lateral movement, and culminating in the encryption of files to disrupt operations. Attackers leverage a variety of tools and techniques including remote desktop protocols for access, NSSM (Non-Sucking Service Manager) for persistence, PsExec for remote command execution, and PowerShell scripts to carry out file encryption. These combined tactics enable LockBit operators to maintain persistence, evade detection, and maximize operational impact within compromised environments.

For European organizations, the LockBit ransomware threat poses significant risks across multiple sectors. The use of DLL sideloading and masquerading complicates detection efforts, increasing the likelihood of prolonged undetected presence within networks. This can lead to extensive data breaches, loss of sensitive information, and operational downtime due to ransomware encryption. Critical infrastructure, healthcare, finance, and manufacturing sectors in Europe are particularly vulnerable given their reliance on Windows-based systems and the high value of their data. The attack chain’s inclusion of credential theft and lateral movement means that once inside, attackers can compromise multiple systems, potentially disrupting supply chains and essential services. The financial impact includes ransom payments, remediation costs, regulatory fines under GDPR for data breaches, and reputational damage. Additionally, the use of legitimate tools for malicious purposes challenges traditional security controls, necessitating more sophisticated detection and response capabilities.

European organizations should implement targeted defenses against DLL sideloading and masquerading techniques. Specifically, they should: 1) Employ application whitelisting and restrict execution of untrusted DLLs by configuring Windows Defender Application Control or similar solutions to enforce strict DLL loading policies. 2) Monitor and audit the use of trusted executables known to be abused (e.g., Jarsigner.exe, MpCmdRun.exe, Clink_x86.exe) for anomalous behavior or unexpected DLL loads. 3) Utilize Endpoint Detection and Response (EDR) tools capable of detecting process hollowing, DLL injection, and masquerading activities. 4) Harden privilege management by enforcing least privilege principles and regularly auditing administrative accounts to prevent privilege escalation. 5) Implement network segmentation and restrict lateral movement by limiting remote desktop access and blocking unauthorized use of tools like PsExec and NSSM. 6) Conduct regular threat hunting exercises focused on identifying indicators of compromise such as suspicious DLL hashes and domain names (e.g., msupdate.updatemicfosoft.com). 7) Maintain up-to-date backups with offline or immutable copies to enable recovery without paying ransom. 8) Educate users on phishing and social engineering tactics that may lead to initial access. 9) Deploy PowerShell logging and restrict script execution policies to detect and prevent malicious script-based encryption activities.