The Hidden Threat Lurking in Legitimate Platforms
A phishing campaign with a particularly devious strategy has emerged, targeting Microsoft's Azure account users through an exploitation of HubSpot, a popular customer relationship management (CRM) platform. This campaign focuses on industries such as automotive, chemical, and industrial manufacturing across Germany and the UK, but its lessons cast a much wider net—Windows users everywhere need to pay attention.
What makes this campaign stand out? It doesn't target vulnerabilities in software but rather cleverly abuses a legitimate platform—HubSpot’s "Free Form Builder." The bad guys essentially turned a trusted tool into a Trojan horse. Let’s dive into how they executed this massive social-engineering plot, how it works, and most importantly, what you can do to protect yourself.
The Anatomy of the Attack: Breaking it Down
Phase 1: The Bait—Leveraging HubSpot’s Free Form Builder
HubSpot, one of the most widely used CRM systems for marketing, sales, and customer service, was weaponized in this attack. Specifically, its "Free Form Builder" feature was used to craft at least 17 fake forms. These forms weren’t just the classic "Hi, you've won a free iPhone" scams. No, they were expertly designed to mimic legitimate, recognizable systems like Microsoft Azure, DocuSign, and even French notary portals.
- How They Did It:
The forms appeared professional and credible, leveraging HubSpot-hosted URLs. Because HubSpot is considered a legitimate domain, email security tools often didn’t flag these phishing emails as suspicious. This is the equivalent of a thief wearing an expensive suit to blend into an upscale neighborhood—it’s harder to spot malice when the presentation looks credible.
Phase 2: The Hook—DocuSign Mimicry
The phishing emails carried DocuSign-branded PDFs or embedded HTML links that evoked trust. Once opened, these documents would redirect users to the fake HubSpot forms. These forms then funneled unsuspecting users toward phishing pages hosted on ".buzz" domains. Some of these pages accurately mimicked Microsoft Outlook Web App and Azure login portals, presenting users with login fields that were indistinguishable from the real deal.
Here’s the kicker: those same emails failed industry-standard email authentication checks like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC. But because the domain behind them was a known legitimate service—HubSpot—the emails slipped past most security solutions.
Phase 3: Credential Theft—Passing Through HubSpot to the Trap
Once redirected to the spoofed Microsoft pages, victims entered their Azure or Outlook account credentials. These credentials were then harvested by threat actors who reportedly pilfered over 20,000 accounts by targeting organizations across Europe.
Phase 4: The Aftermath—A "Tug-of-War" For Control
Post-compromise, attackers used VPNs to blend in, pretending to access accounts from the victim’s country of origin. In some instances, organizations detected unauthorized changes and tried regaining control. This led to what researchers called a "tug-of-war," where the attacker and victim struggled to retain access to the compromised account.
Naturally, even if victims managed to regain control, the attacker likely already accessed sensitive data or used the account for further phishing attempts.
Why Does This Campaign Work So Well?
This attack teaches us (uncomfortably) just how good attackers have become at exploiting human trust and legitimate infrastructure. Here are the critical components of this successful scheme:
- Trusted Platforms as Cover: By using HubSpot—a widely trusted CRM service—the attackers bypassed common email detection methods.
- Clever Phishing Emails: Embedding links to PDFs or HTML documents that redirect to their phishing sites allowed attackers to escape many traditional email scans.
- Localized Targeting: Tailoring their post-access VPN configurations to appear in the victim’s geographic location made it even harder for organizations to detect abnormal activity.
- Abuse of Authentication Gaps: While the campaign failed SPF, DKIM, and DMARC checks, it still bypassed security tools. Why? The links pointed to a reputable domain, tricking filters.
Widening the Lens: Broader Implications
You might think, "I’m not in an automotive plant in Germany or the UK—this doesn’t concern me." Think again. This campaign is a warning for all Windows and Microsoft users. The creative use of legitimate platforms like HubSpot could be replicated with other services, such as Dropbox, SharePoint, or even Teams.
Phishing campaigns are increasingly sophisticated, no longer relying on laughably bad grammar or requests from a "Nigerian prince." Instead, they operate in the gray area where legitimate services are manipulated to their malicious advantage.
Steps to Protect Yourself and Your Organization
Here’s what you can do right now to avoid becoming the next victim:
For Individuals:
- Inspect Sender Information: Even if an email looks legitimate, verify the sender’s domain. Watch for failures in SPF, DKIM, and DMARC when using email software that displays such details.
- Never Click Unknown Links or Attachments: Always hover over links to confirm their URL before clicking. Attachments are riskier than ever; verify their source offline if necessary.
- Enable Two-Factor Authentication (2FA): Even if attackers get your credentials, 2FA adds another blockade. Use Microsoft Authenticator or other trusted apps.
For Businesses:
- Invest in Advanced Email Security: Go beyond traditional email filtering. Look into solutions that allow AI-based behavioral analysis to detect suspicious activity, such as links redirecting to unexpected sites.
- Create Phishing Simulations: Educate employees with regular phishing awareness programs. Many services let you run fake campaigns to sharpen skills against real threats.
- Monitor Login Activity Aggressively: Use services like Microsoft Azure’s Conditional Access Policies to establish geofencing rules and receive alerts for suspicious logins. Threat Intelligence tools are also useful in identifying new rogue ASNs (Autonomous System Numbers) like the ones used in this attack.
The Why Behind Awareness
This isn’t just about avoiding stolen credentials. A compromised Azure account can lead to cataclysmic consequences for organizations. From accessing email systems, files, and critical applications to launching internal phishing campaigns, attackers can treat your compromised account as a wide-open front door.
Final Thoughts: Phishing in the Age of HubSpot Abuse
This attack is a stark reminder that no platform is too "legitimate" to be abused. Your best defenses are awareness, multi-layered security frameworks, and taking proactive measures before, not after, an attack occurs.
Remember, phishing doesn’t care how tech-savvy you believe you are—it bets on your trust in the systems you use daily. The battle against phishing isn’t just about smart tools; it’s about smarter users.
What do you think about this latest campaign? Let us know your thoughts and how you stay phishing-resilient in the comments below!
Source: BleepingComputer HubSpot phishing targets 20,000 Microsoft Azure accounts
Phase 1: The Bait—Leveraging HubSpot’s Free Form Builder
HubSpot, one of the most widely used CRM systems for marketing, sales, and customer service, was weaponized in this attack. Specifically, its "Free Form Builder" feature was used to craft at least 17 fake forms. These forms weren’t just the classic "Hi, you've won a free iPhone" scams. No, they were expertly designed to mimic legitimate, recognizable systems like Microsoft Azure, DocuSign, and even French notary portals.- How They Did It:
The forms appeared professional and credible, leveraging HubSpot-hosted URLs. Because HubSpot is considered a legitimate domain, email security tools often didn’t flag these phishing emails as suspicious. This is the equivalent of a thief wearing an expensive suit to blend into an upscale neighborhood—it’s harder to spot malice when the presentation looks credible.
Phase 2: The Hook—DocuSign Mimicry
The phishing emails carried DocuSign-branded PDFs or embedded HTML links that evoked trust. Once opened, these documents would redirect users to the fake HubSpot forms. These forms then funneled unsuspecting users toward phishing pages hosted on ".buzz" domains. Some of these pages accurately mimicked Microsoft Outlook Web App and Azure login portals, presenting users with login fields that were indistinguishable from the real deal.Here’s the kicker: those same emails failed industry-standard email authentication checks like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC. But because the domain behind them was a known legitimate service—HubSpot—the emails slipped past most security solutions.
Phase 3: Credential Theft—Passing Through HubSpot to the Trap
Once redirected to the spoofed Microsoft pages, victims entered their Azure or Outlook account credentials. These credentials were then harvested by threat actors who reportedly pilfered over 20,000 accounts by targeting organizations across Europe.Phase 4: The Aftermath—A "Tug-of-War" For Control
Post-compromise, attackers used VPNs to blend in, pretending to access accounts from the victim’s country of origin. In some instances, organizations detected unauthorized changes and tried regaining control. This led to what researchers called a "tug-of-war," where the attacker and victim struggled to retain access to the compromised account.Naturally, even if victims managed to regain control, the attacker likely already accessed sensitive data or used the account for further phishing attempts.
Why Does This Campaign Work So Well?
This attack teaches us (uncomfortably) just how good attackers have become at exploiting human trust and legitimate infrastructure. Here are the critical components of this successful scheme:- Trusted Platforms as Cover: By using HubSpot—a widely trusted CRM service—the attackers bypassed common email detection methods.
- Clever Phishing Emails: Embedding links to PDFs or HTML documents that redirect to their phishing sites allowed attackers to escape many traditional email scans.
- Localized Targeting: Tailoring their post-access VPN configurations to appear in the victim’s geographic location made it even harder for organizations to detect abnormal activity.
- Abuse of Authentication Gaps: While the campaign failed SPF, DKIM, and DMARC checks, it still bypassed security tools. Why? The links pointed to a reputable domain, tricking filters.
Widening the Lens: Broader Implications
You might think, "I’m not in an automotive plant in Germany or the UK—this doesn’t concern me." Think again. This campaign is a warning for all Windows and Microsoft users. The creative use of legitimate platforms like HubSpot could be replicated with other services, such as Dropbox, SharePoint, or even Teams.Phishing campaigns are increasingly sophisticated, no longer relying on laughably bad grammar or requests from a "Nigerian prince." Instead, they operate in the gray area where legitimate services are manipulated to their malicious advantage.
Steps to Protect Yourself and Your Organization
Here’s what you can do right now to avoid becoming the next victim:For Individuals:
- Inspect Sender Information: Even if an email looks legitimate, verify the sender’s domain. Watch for failures in SPF, DKIM, and DMARC when using email software that displays such details.
- Never Click Unknown Links or Attachments: Always hover over links to confirm their URL before clicking. Attachments are riskier than ever; verify their source offline if necessary.
- Enable Two-Factor Authentication (2FA): Even if attackers get your credentials, 2FA adds another blockade. Use Microsoft Authenticator or other trusted apps.
For Businesses:
- Invest in Advanced Email Security: Go beyond traditional email filtering. Look into solutions that allow AI-based behavioral analysis to detect suspicious activity, such as links redirecting to unexpected sites.
- Create Phishing Simulations: Educate employees with regular phishing awareness programs. Many services let you run fake campaigns to sharpen skills against real threats.
- Monitor Login Activity Aggressively: Use services like Microsoft Azure’s Conditional Access Policies to establish geofencing rules and receive alerts for suspicious logins. Threat Intelligence tools are also useful in identifying new rogue ASNs (Autonomous System Numbers) like the ones used in this attack.
The Why Behind Awareness
This isn’t just about avoiding stolen credentials. A compromised Azure account can lead to cataclysmic consequences for organizations. From accessing email systems, files, and critical applications to launching internal phishing campaigns, attackers can treat your compromised account as a wide-open front door.Final Thoughts: Phishing in the Age of HubSpot Abuse
This attack is a stark reminder that no platform is too "legitimate" to be abused. Your best defenses are awareness, multi-layered security frameworks, and taking proactive measures before, not after, an attack occurs.Remember, phishing doesn’t care how tech-savvy you believe you are—it bets on your trust in the systems you use daily. The battle against phishing isn’t just about smart tools; it’s about smarter users.
What do you think about this latest campaign? Let us know your thoughts and how you stay phishing-resilient in the comments below!
Source: BleepingComputer HubSpot phishing targets 20,000 Microsoft Azure accounts
