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

• Information Theft
• Security Bypass

Indicators of Compromise

MD5

• 9c0f4f8b74d0c49c28997dcc175897c9
• 8c0ef68bfe8b4f2d72ca3599aedb6387

SHA-256

• 9fd8a479a9f54341cfea3c2906cbc779c8623a288708ac00e21a486f325e3934
• 4b2a32c7afbfb44a85d88bfd4f0a79306278d880c64a28bf3242dc686665c8fe

SHA-1

• 56aedf510fe21edf7f5deb00b210e50f54f44443
• b6c02d95c26e2ec62ba27d0e4c3cd3b1e7f25261

Remediation

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