Rewterz Threat Alert – Remcos Backdoor Malware
February 3, 2021Rewterz Threat Alert – SystemBC/BuerLoader Malware Fetches Cobalt Strike Post Infection
February 4, 2021Rewterz Threat Alert – Remcos Backdoor Malware
February 3, 2021Rewterz Threat Alert – SystemBC/BuerLoader Malware Fetches Cobalt Strike Post Infection
February 4, 2021Severity
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
Filename
- EXTERNAL RFP – PAN India Epoxy PU – 2021[.]gz
MD5
- 1c8b24fcf8143c9035ee722ec8714eb0
- 334c695eac94bb41f4161f4e41e49dd7
SHA-256
- 3eedfdc115ff82f4f23c404fea543d2726ed2d7f1e6e60012dab92345ebae287
- d080047c12bda67d63c8ab49edbd28e2d5bc6694e1a7943bdb2f46a6832a5f53
SHA1
- 1150b1748cb1079535edb9ae2a6e8a12d089ae88
- 7ae32ca453f82daf8a3cdacfea761597d32000f2
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.