Rewterz Threat Alert – GuLoader Malspam Campaign – Active IOCs

Severity

Mediium

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

• f277b08ce4048f9f1ebe318235969c86
• 9162dfe57964eb774b778da435d3ba5f
• aa4266b1d2804d95fa378490c1b7e18a
• c1dad5e01dccc8d4ea8f004ee559adae
• 2b5646556eac75525e56a43a13faeac5

SHA-256

• 14fb3902c8ff3e8d045b387ec1aefac1cee3fab81f2e60ce6ecd11e062fd91ac
• 384d7fc0bb89b0fec770a1fffd775f9dee8e6ca461d443b6cfe9fc867f008674
• 1e7519092c25c4ca7049766ca8e73dbea51a7b6a057a5e086f59da7c86437071
• dfb645322c12b830f6dd90f7f3669ebba3a49ac3910e9962f732b127bf5c1ec6
• 17591a1818c3e80dbddd26fa86566152ca06d64e7d0ada9a709e68bb59bf5bd1

SHA-1

• 551320c05acf2f45242cb4d0ab980df0ac6974f7
• 06ab6fd94f7b3b8407027b8c964943df49106331
• 8f8532162b8c1d49895e79b6d2988cf1b8aafeae
• 74aafe9de51aecab50069ce565e08b098311818b
• 709b337ac9eda16c0f5ad3f81530373b48262b19

Remediation

• Maintain cyber hygiene by updating your anti-virus software and implement patch management lifecycle.
• Maintain Offline Backups – In a ransomware attack, the adversary will often delete or encrypt backups if they have
• access to them. That’s why it’s important to keep offline (preferably off-site), encrypted backups of data and test them
• regularly.
• Emails from unknown senders should always be treated with caution.
• Never trust or open ” links and attachments received from unknown sources/senders.
• Block all threat indicators at your respective controls.
• Search for Indicator of compromise (IOCs) in your environment utilizing your respective security controls