Microsoft Engineer Accidentally Leaked 4GB of PlayReady DRM Internal Code Used To Protect Streaming Services
26 June 2024 at 15:45
PlayReady DRM Internal Code Leak
In early June, a Microsoft engineer had published information about an Apple TV service crash on a Surface Pro 9 device in a public forum. The shared data included a 771MB file attachment that revealed 4GB of internal code related to Microsoft PlayReady upon extraction. [caption id="attachment_79066" align="alignnone" width="1920"]![Microsoft PlayReady DRM Internal](../themes/icons/grey.gif)
![PlayReady DRM Internal Code Leak Microsoft](../themes/icons/grey.gif)
HD Keys Could Be Decrypted
Researchers from cybersecurity company AG Security Research Lab managed to successfully build the required Windows PlayReady DLL library from the leaked internal code, aided by step-by-step instructions provided by another user on the same forum. Their investigation uncovered several deficiencies in Protected Media Path (PMP) components of PlayReady, which could be exploited to access plaintext content keys secured by the system on Windows 10 and 11 systems. The researchers demonstrated that these extracted keys could successfully decrypt high-definition movies protected by PlayReady. Notably, the vulnerability persists even on systems with hardware DRM capabilities, as this feature can be easily disabled. The root cause appears to lie in the software DRM implementation used by default on Windows 10 systems without hardware DRM capability. Given that Windows 10 still holds a 69% market share worldwide, this vulnerability could potentially affect a significant number of users until the operating system's retirement in October 2025. The team also demonstrated that the technique used to extract plaintext values of content keys could work for other platforms relying on SW Microsoft PlayReady technology in a Windows OS environment.Implications and Microsoft's Response
The researchers had notified Microsoft about the leak on June 12, 2024. While Microsoft removed the forum post within 12 hours, the download link reportedly remained active. On June 26, MSRC stated to the researchers that it had conducted an investigation and determined that the incident was not a vulnerability to service as the post had already been taken down. The researchers confirmed that the download link no longer remains active. The incident highlights the ongoing challenges in maintaining the security and secrecy of DRM implementations. It also underscores the importance of adhering to guidelines for handling sensitive information in public forums, as the leak violated Microsoft's own guidelines for posting link reproduction information publicly. These guidelines specify:- All information in reports and any comments and replies are publicly visible by default.
- Don't put anything you want to keep private in the title or content of the initial report, which is public.
- To maintain your privacy and keep your sensitive information out of public view, exercise caution.