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

• e39cccd2c1f0998f0e34fa525132868d
• cbdf1bd3b8c6d5d8ea358fad8b83becc
• c2c790809328c92c0eec843aceb3be64

SHA-256

• d9040bf8ad755cd41dc6266c0e0049f4bac0eaa23f18a26931357fe21c719701
• 6d05c6f5356b5d1a4802d1b110dd5e6b9136f0b61081130f02404a9312fcd5fe
• 25b1b9c09860911a5e932106bda457849099223f19ee11fca9076c47bb837a67

SHA-1

• 94b39b2dcf8682cb2b5b039428219ca4a6d6eb6b
• 36e0b2d2d2629d768d6c8f6d1383ae671195cd73
• ded2b5d8e2b48b48d737a699ab371cc64ebef2d9

Remediation

• Block the threat indicators at their respective controls.
• Do not download files attached in untrusted emails.
• Do not download files from untrusted sources on the internet.
• Search for IOCs in your environment.