Rewterz Threat Alert – GuLoader Malspam Campaign – Active IOCs

Severity

Medium

Analysis Summary

Guloader is currently being distributed via spam email campaigns with archived attachments that contain the malware. The majority of malware downloaded by GuLoader is commodity malware, with AgentTesla, FormBook, and NanoCore being the most predominant. This downloader typically stores its encrypted payloads on Google Drive. It has also downloaded its payloads from Microsoft OneDrive and also from compromised or attacker-controlled websites. By utilizing legitimate file-sharing websites, GuLoader can evade network-based detection, as these services are not generally filtered or inspected in corporate environments. Usually, the downloaded payloads are encrypted with a hard-coded XOR key embedded in the malware, making it difficult for file-sharing service providers to identify the payload as malicious. This time, the GuLoader Shellcode injector is being distributed via a file named “EXTERNAL RFPPAN India Epoxy/PU 2021”. The scope of this campaign so far seems to be global.

Impact

• Malware installation
• detection evasion
• Information theft

Indicators of Compromise

MD5

• 24fa5e97c7670d25c0420576f43368d7
• e5bca066c2f12119f5b3bb90ae1750b2
• b135c68ebb14290a673ddda311383072

SHA-256

• 546c47c79f996ce4f559a72e8e79e19c9f53b0af102fe68340e703c958cfd044
• b3c874789f39680ef573773cbb896e400f468fcc9e07998f5d69fc539940f179
• 7c4e27cee456be8b3a430d8a2d61793e4fac26e0e8e4833b4cf733ba18f35e5f

SHA-1

• 27b1a9271cb6901086e5d6c40aa737c2900eee5a
• 236f527f66817d58ab99269737e4ace7fe20c140
• 607df93271697c4084d323cacb28687243997e81

Remediation

• Block the threat indicators at their respective controls.
• Search for IOCs in your environment.