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 evation
• Information theft

Indicators of Compromise

MD5

• 55bfd6081f970ff35de19f84dbd78c85
• acefc67c8d528262aa4863fd7e063303
• 5c3742c9290e98bc78edce6d80f56766

SHA-256

• b0e21aa372ef7862cc07b3f9fed6eb6d0d119a98a0af7bdc5bd13688964c5e08
• 25348cea549492a95bb8fe5f3982388e9e694cdbb60079e5131df23aa9820d83
• 6f62460d1e70d0ba87c302e19c2b3ffae493c98b6cd20c4320ff68ede0b6d071

SHA-1

• 6b30036a9d198f7a527b68801710869669af1833
• 00c51737bdd1238a9c5f56fbe6ad329880d8d1b4
• 55e0a91e6725102c85468c52b3ec55d1f9876632

Remediation

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