Phishing attack response starts with recognizing that attackers are now using blank sender addresses to bypass Microsoft 365 filters while masquerading as internal emails, making employee training and email controls your first line of defense. Small manufacturers and professional services firms need immediate steps: verify sender identity through a second channel, disable blank-sender emails at the gateway, and log all suspicious messages for incident review.
Today's cybersecurity landscape shows a dangerous convergence: AI is supercharging both attacks and exploitation of old vulnerabilities. Microsoft 365 users are being targeted with a sophisticated phishing technique where attackers use blank sender addresses to bypass security filters while appearing to be internal emails. Meanwhile, a 12-year-old PostgreSQL database vulnerability dubbed PostGREShell is now being actively exploited, allowing attackers to take complete control of servers.
Most concerning is the rise of AI-powered cyberattacks. Chinese hacking groups are deploying AI agents like Claude and DeepSeek to automate attacks against government and industrial targets worldwide. These AI tools are making attacks faster, more sophisticated, and harder to detect. Even a four-year-old voting system vulnerability in Georgia was recently exploited using AI coding tools, demonstrating how artificial intelligence can breathe new life into old security flaws.
Google has patched its sixth Chrome zero-day vulnerability of 2026, emphasizing the importance of keeping browsers updated. For small business owners, the message is clear: the threat landscape is evolving rapidly. Success requires a multi-layered approach, keep all software patched, train employees to spot phishing attempts, and stay informed about emerging AI-powered threats.
How should a small business handle a phishing attack response?
Microsoft 365 users are being targeted with a new phishing technique using blank sender addresses to slip past security filters. The attack works because it appears internal, lowering employee guard. For a small business, this means your current email training may not catch this tactic. CISA recommends immediate actions: configure your mail gateway to reject blank senders, run a phishing simulation with your team using this specific method, review recent email logs for suspicious activity, and establish a clear protocol for staff to report unusual internal emails to IT. The single most important action is disabling blank-sender emails at your gateway today, then testing your filters with a security consultant.
Key takeaways
- Blank-sender phishing emails bypass standard filters by appearing internal. Configure your email gateway to reject them immediately.
- AI-powered attacks are automating exploitation of old vulnerabilities like PostGREShell (12-year-old PostgreSQL flaw). Patch all systems on a fixed schedule.
- Google patched its sixth Chrome zero-day of 2026. Enable automatic browser updates across all workstations and devices.
- Train your team on this specific phishing technique monthly. Use real examples from your industry (manufacturing, professional services).
Frequently asked questions
What makes this phishing attack different from standard spam?
This attack uses blank sender addresses to bypass email filters while appearing to come from inside your organization. Employees are more likely to trust internal-looking emails, making them click links or download attachments. Standard filters often allow internal emails through without additional scrutiny.
How do I block blank-sender emails in Microsoft 365?
In Exchange Online, create a mail flow rule that rejects messages with empty sender fields. Work with your IT provider or MSP to implement this in your environment. Test the rule with a pilot group before rolling it out company-wide to avoid blocking legitimate emails.
What should I do if an employee clicks a phishing link?
Reset their password immediately, check for unauthorized email forwarding rules, review recent emails sent from their account, and scan their device for malware. Report the incident to your MSP or IT provider and document it for future incident response planning.
Why should I care about a 12-year-old PostgreSQL vulnerability?
PostGREShell gives attackers complete server control and is being actively exploited now. If your business runs any legacy databases or third-party applications using PostgreSQL, you are at risk. Contact your software vendors for patches and prioritize database patching in your maintenance schedule.