A sophisticated phishing campaign, known as “Gabagool,” has recently been discovered by the TRAC Labs team, targeting corporate and government employees. The campaign exploits Cloudflare’s R2 storage service, using its trusted infrastructure to host malicious content and evade security filters. Attackers leverage the reputation of Cloudflare’s infrastructure to bypass security systems, making it more difficult for traditional defenses to identify and block the malicious content. The phishing attack begins with compromised mailboxes, which send phishing emails containing links disguised as documents, leading the recipient through a chain of file-sharing platforms to a Cloudflare R2 bucket page.
The malicious page hosted on Cloudflare’s R2 service utilizes a URL format that hides its true intent, making it harder for security filters to detect. The page then employs various bot detection mechanisms to ensure that the user is a real person, not a bot. These techniques include checks for mouse movement, rapid interactions, and cookie tests, all of which are designed to ensure the attacker can control the victim’s interaction with the phishing site. If suspicious bot activity is detected, the user is redirected to a legitimate domain, but if the victim passes the checks, they are shown the phishing page after a brief delay.
The phishing page itself is designed to capture user credentials through AES encryption, which protects the server address. Once the victim inputs their login information, it is sent to the attacker’s server for harvesting. Gabagool has a particularly dangerous feature, as it is capable of bypassing multi-factor authentication (MFA) by handling various authentication methods, such as phone app notifications, SMS, and voice calls. This makes it more difficult for users to protect their accounts, even if they have MFA enabled. The attackers can use this capability to gain unauthorized access to sensitive corporate and government data.
To defend against the Gabagool phishing campaign, security teams are advised to monitor unusual connections to Cloudflare R2 buckets and keep an eye out for traffic directed to known malicious servers, such as o365.alnassers.net, which is associated with the attack. Regular review of network traffic and using public URLScan queries to identify suspicious URLs can also help in detecting and mitigating these threats. As phishing campaigns continue to evolve, organizations must remain vigilant and adapt their security measures to protect against increasingly sophisticated threats like Gabagool.
