In the ever-evolving game of cat and mouse between threat actors and defenders, a new and insidious tactic has emerged, one that leverages the familiarity and trust placed in everyday tools like Microsoft SharePoint.
Security analysts at CyberProof’s Security Operations Center (SOC) have recently uncovered a surge in phishing campaigns that subtly exploit SharePoint’s legitimacy to bypass traditional detection systems. Unlike the blunt instruments of older phishing attempts, these campaigns are polished, precise, and worryingly effective.
Exploiting Familiarity and Trust
Instead of embedding obvious malicious links, attackers are now disguising credential-harvesting URLs as genuine SharePoint file-sharing links. These URLs, camouflaged within authentic-looking emails, slip past email gateways and endpoint defenses. Why? Because SharePoint is inherently trusted and therein lies the danger.
These links don’t immediately raise alarms. They’re hosted dynamically and often expire after a short time, rendering automated scanners and sandboxes ineffective. The result? Malicious domains can be recycled across multiple, targeted campaigns without drawing attention.
A Sophisticated Multi-Stage Trap
These aren’t your average phishing emails. Many campaigns are built with the precision of spear-phishing. They begin with what looks like a normal corporate communication, an email bearing a SharePoint link. But only the intended recipient can progress, passing through what appears to be a Microsoft identity verification phase.
Victims who enter their credentials are given a legitimate Microsoft validation code. This extra step reinforces the illusion of authenticity. Once the code is submitted, they’re led to a fake SharePoint login page crafted solely to harvest their sensitive information.
Hidden Backdoors and Persistent Threats
Once the attackers gain access, they don’t stop there. Post-compromise actions include:
- Adding malicious inbox rules to hide future phishing activity.
- Installing hidden MFA methods to maintain long-term access.
- Using compromised accounts to send more phishing emails turning victims into unwilling accomplices.
- Inviting hundreds of external users to the SharePoint environment, allowing lateral movement and data exfiltration.
Some campaigns blur the line between internal and external threats, especially when the phishing emails originate from accounts with which the organization has previously communicated. This social engineering component makes detection even more elusive.
The New Defensive Playbook
Traditional defenses are no longer sufficient. Organizations need to shift to proactive detection strategies. This includes:
- Monitoring sign-in activities and audit logs linked to SharePoint interactions.
- Investigating proxy logs during the timeframe of validation code receipt.
- Resetting user passwords and removing unauthorized MFA methods immediately upon suspicion.
- Deleting phishing emails and harmful inbox rules swiftly to contain the breach.
But above all, user awareness remains the cornerstone. No technical control can completely protect an organization if users are not trained to recognize and report suspicious activity.
Conclusion
The battlefield has shifted. Trust, once a strength, is now a vulnerability. With attackers weaving deception into platforms like SharePoint, security must evolve beyond checklists and basic alerts. It must become anticipatory rooted in behavior, vigilance, and education.
The adversaries are watching, waiting, and adapting. The question is are you?
About COE Security
COE Security partners with organizations in financial services, healthcare, retail, manufacturing, and government to secure AI-powered systems and ensure compliance. With the growing threat of social engineering especially through platforms like SharePoint COE Security is uniquely positioned to help your organization stay ahead of evolving phishing threats.
We offer:
- AI-enhanced threat detection and real-time monitoring to identify suspicious SharePoint activity.
- Customized phishing simulations and user training programs to prepare your team against social engineering tactics.
- Data governance aligned with GDPR, HIPAA, and PCI DSS to ensure legal and regulatory compliance post-breach.
- Penetration Testing (Mobile, Web, AI, Product, IoT, Network & Cloud) to assess the resilience of your entire environment.
- Secure model validation to protect your AI deployments from adversarial abuse.
- Secure Software Development Consulting (SSDLC) to embed security early in your workflows.
- Customized CyberSecurity Services tailored to the phishing and social engineering threats facing your industry.
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