Rewterz Threat Update – Behind the Rise of the Million Dollar Zero-Day Market
November 25, 2021Rewterz Threat Advisory – CVE-2021-4002 – Linux Kernel Vulnerability
November 26, 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.
Impact
- Information Theft
- Security Bypass
Indicators of Compromise
MD5
- e0f03ce55d8d032cc7e3b7d271f53690
- 0bb989d50bfb9833b4efd6e732954875
- 812181df251e06433bf2f4f6a0c0f0f4
SHA-256
- 738fbb1e94a5139a174a53e4db9afa26d6f7ee73e773863e62640b1b0c2d3099
- 1750cf33164b225df42684d628c2a405292bdcdad62ff729171a95849cfea8ff
- 0380d3287b80ff4a26c4ee700e3f16472efca76f27865cf5bab9d382fc5e25c1
- 4d6c910a379d00f329e55ad98a7817de0370695566443a74a9a02c85d2463a9d
SHA-1
- bd339f199ad882d17310ce9af9e21dc7d688e6cd
- 9ae4f7f53be9329be628dbd137e18d3838d3f425
- aa38a567ee48483d98966622fd320c791bc45871
Remediation
- Search for IOCs in your environment.
- Block all the threat indicators at your respective controls.
- Do not download files attached in untrusted emails.
- Do not download files from untrusted sources on the internet