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2025-01-02
LegionLoader, a sophisticated C/C++ downloader malware first observed in 2019, has continually evolved its tactics to evade detection and maximize its impact. Initially focused on delivering malicious payloads, it has expanded its capabilities to include the delivery and execution of malicious Chrome extensions. These extensions possess a wide range of malicious functionalities, including:
Email Manipulation: Altering email content, potentially for phishing campaigns or spreading misinformation.
Data Theft: Stealing browsing history, capturing screenshots, and monitoring user activity on various platforms, including social media (Facebook), cryptocurrency exchanges (Coinbase), and digital payment services (Google Pay).
System Compromise: Turning compromised browsers into HTTP proxies, enabling attackers to leverage infected systems for further malicious activities.
Furthermore, LegionLoader has integrated with other malware families, such as LummaC2, Rhadamanthys, and StealC, to deliver a broader range of malicious payloads, including credential stealers.
Dissemination and Infection:
LegionLoader primarily spreads through drive-by downloads, enticing victims to visit websites hosting fake installers or software updates. These deceptive websites lead to the delivery of payloads via services like RapidShare, which ultimately redirect to MEGA.
The infection process involves the execution of an MSI file, which collects system information (date, time, and language) to retrieve a decryption password from a remote server. This password is then used to decrypt a ZIP archive containing a malicious DLL file.
The DLL file is injected into a legitimate system process (explorer.exe) using the process hollowing technique. This method allows the malware to execute in the context of a trusted process, evading security measures.
Command and Control (C2) Communication:
LegionLoader communicates with a C2 server to receive further instructions. The communication is encrypted using RC4 and Base64 encoding. The malware employs a Mersenne Twister random number generator to generate unique identifiers for each communication request, making it more difficult to detect and block.
Malicious Chrome Extension Delivery:
A key aspect of
Download malicious Chrome extensions from specific URLs.
Install these extensions into the
Grant the extensions necessary permissions to execute malicious actions.
Persistence Mechanisms:
LegionLoader employs various techniques to maintain persistence on the infected system. These include:
Downloading and executing files with names generated using the Mersenne Twister algorithm.
Placing malicious executables (renamed to “svchost.exe”) in the %TEMP% folder.
Utilizing legitimate system utilities like “rundll32.exe” and “ShellExecuteA” to execute malicious code.
Indicators of Compromise (IOCs):
To mitigate the threat of LegionLoader, organizations and individuals should monitor for the following IOCs:
Suspicious HTTP GET requests to specific URLs associated with LegionLoader’s C2 servers.
The presence of unexpected “svchost.exe” files in the %TEMP% folder.
The presence of ZIP and MSI files with specific naming conventions in the Downloads folder.
Unusual network traffic originating from the “explorer.exe” and “Chrome” processes.
Connections to crypto domains associated with cryptocurrency theft.
The presence of a malicious Chrome extension named “Save to Google Drive” in specific AppData locations.
Analysis of PowerShell activity for base64-encoded commands and suspicious scripts.
What Undercode Says:
LegionLoader represents a significant threat due to its continuous evolution and the increasing sophistication of its attack vectors. The integration of malicious Chrome extensions significantly expands its capabilities, enabling attackers to steal sensitive data, manipulate user behavior, and compromise system integrity.
The use of obfuscation techniques, such as encrypted communication and obfuscated PowerShell scripts, makes detection and analysis more challenging.
Furthermore, the reliance on legitimate system processes and utilities for execution helps the malware evade traditional security measures.
This highlights the importance of robust endpoint security solutions, including:
Antivirus and anti-malware software: Regularly updated and capable of detecting and blocking LegionLoader and its associated payloads.
Intrusion Detection and Prevention Systems (IDPS): To monitor network traffic for malicious activity and block suspicious connections.
Application Whitelisting: To prevent the execution of unauthorized applications.
Regular security assessments and penetration testing: To identify and address vulnerabilities that could be exploited by attackers.
User education and awareness are also crucial. Users should be vigilant about suspicious emails, websites, and software downloads. They should avoid clicking on unknown links, downloading files from untrusted sources, and enabling unnecessary browser extensions.
By implementing a multi-layered defense strategy and staying informed about the latest threats, organizations and individuals can effectively mitigate the risks associated with LegionLoader and other advanced malware.
References:
Reported By: Cyberpress.org
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Wikipedia: https://www.wikipedia.org
Undercode AI: https://ai.undercodetesting.com
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