Rewterz Threat Alert – GuLoader Malspam Campaign – Active IOCs

Severity

High

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, 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

• f21e2c166c5a5bc54c2468e339ace3d9
• fcfb0ec70f1419ede8a534cc95cb61e9
• a614ffba80a73c65f65d075be87886bd

SHA-256

• 0229bf87c2a5aca957fdfd76204c971442b78085ac276a882d35dba3a78ac94e
• ff1b034c7060724133c6df0aa8cf5411ec0e6775d3aca83a127617340a8c588a
• e715b8999667ede59ec874c6f190278b068ce7d8c81a6f5a0137e4767976b801

SHA-1

• 83914b984b3f45a6c5318b8ea39418fedb2be2e1
• d3b529d77f1de00d63a75b3956d4bcf6bbce30ca
• 9647d8a46aeff64a1fcfdf5f238c3396f07357ec

Remediation

• Block all threat indicators at your respective controls.
• Search for IOCs in your environment.
• Always be suspicious about emails sent by unknown senders.
• Never click on links/attachments sent by unknown senders.