CVE-2020-0009

In calc_vm_may_flags of ashmem.c, there is a possible arbitrary write to shared memory due to a permissions bypass. This could lead to local escalation of privilege by corrupting memory shared between processes, with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android kernel Android ID: A-142938932

Weakness

During installation, installed file permissions are set to allow anyone to modify those files.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/127.html
• https://cwe.mitre.org/data/definitions/81.html

References

• http://packetstormsecurity.com/files/155903/Android-ashmem-Read-Only-Bypasses.html
• https://lists.debian.org/debian-lts-announce/2020/06/msg00011.html
• https://lists.debian.org/debian-lts-announce/2020/06/msg00013.html
• https://source.android.com/security/bulletin/2020-01-01