Sophisticated Phishing Attack Targets Microsoft Azure Logins in Europe

A sophisticated phishing campaign targeting European companies has recently come to light, and it is a stark reminder of the evolving threats in the cybersecurity landscape. The attack, peaking in June 2024, aims to harvest Microsoft Azure cloud credentials and compromise the victims’ cloud infrastructure.

Phishing Attack Chain

The campaign primarily targets automotive, chemical, and industrial compound manufacturing companies in Germany and the UK. Researchers estimate that approximately 20,000 users across various European organizations have been affected.

Researchers from Palo Alto highlighted that the phishing messages included either a PDF file enabled with DocuSign as an attachment or an HTML link. These links led victims to harmful HubSpot Free Form Builder links embedded within the phishing emails. The threat actors employ a multi-pronged approach to lure victims:

1. Malicious PDF attachments: Emails contain DocuSign-enabled PDF files with company-specific names, enticing users to click on a “View Document” button.
2. Embedded HTML links: Some emails include links that direct victims to fraudulent websites.
3. HubSpot Free Form Builder: The attackers leverage this legitimate service to create convincing phishing forms.

Several malicious PDF attachments used the target organization’s name in the file name (i.e., CompanyName.pdf). Once a user interacts with these malicious elements, they are redirected to a credential harvesting page designed to mimic Microsoft Azure login portals.

Malicious Document

The phishing infrastructure used in this campaign is highly sophisticated, utilizing multiple levels of redirection and domain names that closely resemble legitimate company websites. For instance, the attackers use top-level domains like “.buzz” to create convincing URLs (e.g., http://www.acmeinc[.]buzz).

Unit 42 researchers identified at least 17 different HubSpot Free Form URLs used in this campaign, highlighting the scale of the operation. The attackers also employed “Bulletproof” VPS hosts, known for their anonymity and resistance to takedown requests. What sets this campaign apart is its persistence techniques.

After compromising an account, the attackers add new devices to the victim’s Azure account, allowing them to maintain access even after password resets. To evade detection, the threat actors use VPN proxies to make their login attempts appear to originate from the same country as the victim organization. They also employ unusual user-agent strings during connection attempts.

Protective Measures for Organizations

Organizations need to adopt comprehensive security measures to defend against such sophisticated phishing campaigns. This incident underscores the urgency for companies to enhance their cybersecurity measures, educate employees about phishing risks, and implement robust strategies to thwart these attacks. Key protective measures include:

1. Employee training: Regularly educate employees about phishing threats and how to recognize suspicious emails and links.
2. Multi-factor authentication (MFA): Implement MFA on all cloud services to add an extra layer of security.
3. Email filtering: Use advanced email filtering solutions to identify and block phishing emails before they reach users’ inboxes.
4. Regular security audits: Conduct frequent security assessments to identify and address vulnerabilities in the organization’s systems.