Rewterz Threat Intel – 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, 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

• 3b23eecb92257cb6ebf99d7011f6952f
• aa2bd93add61460d059367e41d89195c
• 80eb7c9a8a21c041b51e4cb5876018c9
• 93c07fdbfb93282cdea8b02f28f5ad81

SHA-256

• f4bb76dda7c1f264ffdb934f633ecc278acc7a4cb7b0d71248cc1cddde42629f
• 7f347545daf832b84a0cb2d823af46e874cb7c69f436814c58355262e594c4d3
• 5d17f485533870d2b0e4240fe8707f02621641c40f49b014b802cc1e419ced5b
• 49b1cee4deadb9d9d9bd064c7634e8692cd08ccc97cbf60506f4e0c0d3c834f

SHA-1

• 97668e74dbd3eb10efbdc5d6c2f86bc5c4146b25
• 9368ee245f899583bdc97ad8e13f4b02b09dbe38
• f4e40dcb63672b82ec68405a58797d5ef4e11117
• bbf1ab00dd03bc54e0356e0cd6c5d4b12ba54fd5

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.