Phishing Attack Exploits Office 365 Misconfigurations: Is Your Business at Risk?

Phishing is one of the most common cyberattacks businesses experience today. In these schemes, cybercriminals use lures like fraudulent emails and text messages to “fish” for sensitive information from unsuspecting victims. This data can include passwords, credit card numbers, access privileges, and more.

Traditionally, users spot phishing attempts by checking for grammatical errors, unexpected attachments, and suspicious links. However, such threats have become more sophisticated lately, with many exploiting Office 365 misconfigurations to gain unauthorized access to businesses’ internal systems and data.

In this blog post, we’ll discuss how spoofed phishing attacks happen and why businesses must look out for them. Plus, we’ll cover practical steps to protect your organization from these threats and how Techmedics’ managed security services can strengthen your cybersecurity stance.

Spoofed Phishing Attacks, Explained

In a recent blog post, Microsoft Threat Intelligence detailed how more cybercriminals are spoofing target organizations’ Office 365 domains to launch phishing attacks.  

According to the tech giant, organizations that don’t route their emails directly through Office 365 and use third-party filtering services are particularly vulnerable to this attack. The risk increases further if their email routing systems aren’t properly configured with Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting & Conformance (DMARC).

SPF helps receiving mail servers to determine which systems are permitted to send emails on behalf of your domain (e.g., yourmarketingcompany.com). Meanwhile, DKIM adds an encrypted signature to emails to prove they really came from your domain. Finally, DMARC tells receiving mail servers what to do if SPF or DKIM checks fail (none, quarantine, or reject).

Without these safeguards in place, threat actors can send phishing emails that would normally be rejected by security checks.  

For instance, let’s say your business routes emails through a third-party filtering platform like Mimecast or Proofpoint before it reaches Office 365, and your email authentication protocols are missing or not strictly enforced. As a result, cybercriminals can send emails that appear to come from your organization (e.g., ceo@yourmarketingcompany.com, finance@yourmarketingcompany.com).  

By using third-party email routing without enforcing strict security measures, phishing emails can land in employees’ inboxes. Since they appear to come from your domain, employees may trust them and click on malicious links or even wire money.

How Can Email Spoofing Attacks Be Mitigated?

To combat email spoofing used in phishing attacks, Microsoft advises organizations to enforce strict DMARC policies. This means configuring it to quarantine or reject messages that fail authentication checks. “Quarantine” sends suspicious emails to spam/junk folders, while “reject” blocks them entirely, preventing malicious content from reaching a user’s inbox.  

Some businesses initially set DMARC to “none” to monitor results. Once legitimate senders are properly aligned, they then move to stricter policies like “quarantine” or “reject.”

Microsoft also suggests setting SPF to “hard fail,” which prevents attackers from forging your domain in phishing emails. Lastly, Microsoft suggests implementing phishing-resistant authentication solutions. These include:

• Passkeys: These are digital credentials linked to a device that allow users to confirm their identity without entering a username or password. They rely on cryptographic keys stored securely on the device, and can be unlocked using facial recognition, fingerprint scans, or a device PIN.  

• Smart Cards: These are physical cards with embedded chips that securely hold cryptographic keys and certificates used for authentication. Attackers can’t authenticate without physically possessing the card and knowing the PIN.  

• Certificate-Based Authentication: This verifies a user’s or device’s identity using a digital certificate, which functions like an electronic passport to grant access to networks and applications.

Other effective methods to protect your business from suspicious emails include:

• Investigate the Claim: If a coworker or a company executive unusually asks via email to wire money to a bank account, confirm the request first by contacting the sender directly, either via phone call or in-person conversation.

• Identify the Red Flags: Teach employees to spot unusual changes in payment details, urgent requests, and demands to bypass normal approval processes.

• Leverage Behavioral Analytics: Use tools that analyze user and entity behavior to identify and address unusual login patterns or activities.

How Techmedics Can Help Your Business Stay Protected from Spoofed Phishing Attacks

As phishing attacks grow increasingly complex, common security measures may no longer suffice for your business. The good news? A reliable managed security services provider like Techmedics can bolster your security posture. We offer the following services that help secure your systems from phishing and other threats:

• Threat Detection: Mitigate cyberthreats by proactively monitoring network activity, deploying endpoint protection, and leveraging security information and event management (SIEM).

• Incident Response: Our automated systems automatically block malicious activity, isolate affected devices, and escalate incidents to our IT experts for prompt response.

• Phishing Training: Our expert team teaches your employees to identify, avoid, and report suspicious emails, links, text messages, and calls through hands-on exercises and simulated phishing attacks.

Techmedics protects your organization from evolving cyberthreats, empowering its resilience. Get a FREE consultation today to learn more about our services.  

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