Full Report
The msgrcv_nocancel syscall could disclose uninitialized memory from kernel space into userspace. This is due to an incorrect calculation being performed when copying the memory.
Analysis Summary
# XNU Kernel Memory Disclosure Vulnerability
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## Key Points
- A vulnerability exists in the `msgrcv_nocancel` syscall due to incorrect memory calculation.
- The bug leads to disclosure of uninitialized kernel memory into userspace.
- Patches were released for macOS 11.3 and iOS 14.5.
## Threat Actors
- **Apple**: Attribution has not been confirmed, but Apple is involved in the release of patches for this vulnerability.
## TTPs
- The `msgrcv_nocancel` syscall takes user-input message size from userspace.
- Incorrect calculation leads to truncation and subsequent disclosure of uninitialized memory.
## Affected Systems
- **macOS 11.3**: Patch released to fix the vulnerability.
- **iOS 14.5**: Patch released to fix the vulnerability.
## Mitigations
- Ensure all software updates are installed, including patches for macOS 11.3 and iOS 14.5.
- Monitor system logs for potential security breaches related to this vulnerability.
## Conclusion
The XNU kernel memory disclosure vulnerability is a significant security concern due to its potential impact on sensitive data stored in the kernel's memory pool. The patches released by Apple address this issue, but users must ensure they are running the latest software versions to prevent exploitation of this vulnerability.