Microsoft has limited certain Chinese companies' access to its early warning system for cybersecurity vulnerabilities following suspicions about their involvement in recent SharePoint hacking attempts.

The decision restricts the sharing of proof-of-concept code, which mimics genuine malicious software. While valuable for cybersecurity professionals strengthening their systems, the code can also be misused by hackers.

The restrictions follow Microsoft's observation of exploitation attempts targeting SharePoint servers in July. Concerns arose that a member of the Microsoft Active Protections Program may have repurposed early warnings for offensive activity.

Microsoft maintains that it regularly reviews participants and suspends those violating contracts, including prohibitions on participating in cyber attacks.

Beijing has denied involvement in the hacking, while Microsoft has refrained from disclosing which companies were affected or details of the ongoing investigation.

Analysts note that balancing collaboration with international security partners and preventing information misuse remains a key challenge for global cybersecurity programmes.