grumczak[.]github[.]io

This domain, grumczak.github.io, is actively engaged in a high-risk brand impersonation campaign targeting Facebook users. The threat involves a cloned login interface designed to harvest credentials by mimicking the legitimate Facebook authentication page. Analysis of the page title confirms the impersonation attempt, as it explicitly displays 'Facebook,' a clear indicator of brand exploitation for malicious purposes. The campaign poses significant risks, including unauthorized account access, identity theft, and potential lateral movement to connected services or financial platforms linked to the compromised account.

Technical analysis reveals multiple indicators of malicious activity. The domain is registered through GitHub, Inc., leveraging GitHub Pages infrastructure to host the phishing content. It resolves to the IP address 185.199.111.153, associated with AS54113 (Fastly, Inc.), a network frequently utilized for both legitimate and malicious content delivery. The SSL certificate is issued by Let's Encrypt (YR2), providing a false sense of security to potential victims. Detection metrics further substantiate the threat: VirusTotal reports 8 out of 95 security vendors flagging the domain as malicious, and it appears on one security blocklist. These figures underscore the domain's active and recognized threat status within the cybersecurity community.

Users who have interacted with grumczak.github.io should take immediate remedial actions. First, any credentials entered on the site must be considered compromised and changed without delay, starting with the targeted Facebook account and extending to any other platforms where identical or similar credentials may have been reused. Enable multi-factor authentication (MFA) on all critical accounts to mitigate the risk of unauthorized access. Monitor the affected accounts for suspicious activity, such as unauthorized logins, password changes, or unauthorized posts. If financial or personally identifiable information (PII) was exposed, consider placing a fraud alert or credit freeze with relevant bureaus. Finally, report the incident to the targeted brand's security team and relevant authorities to aid in broader mitigation efforts.