Microsoft has issued a warning about ViewState code injection attacks that can result in remote code execution. These attacks exploit a vulnerability in ASP.NET websites, where cybercriminals are injecting malicious code into the ViewState feature, which stores user input and page settings. Many developers are using publicly available machine keys, making it easy for attackers to inject harmful content into websites. To prevent these attacks, developers are advised to generate their own machine keys, avoid using default keys, encrypt sensitive data, upgrade ASP.NET versions, and utilize security features like AMSI. Microsoft has also removed insecure machine key examples from public documentation. Hackers are increasingly hiding malware in website images, and for enhanced security, consider using password managers and authenticator apps.