CVE-2020-8904 : Exploit Details and Defense Strategies

An arbitrary memory overwrite vulnerability in the trusted memory of Asylo exists in versions prior to 0.6.0. This vulnerability allows an attacker to manipulate the tmp_output_len value and write to an arbitrary location in the trusted memory.

Understanding CVE-2020-8904

Asylo, a product by Google LLC, is affected by an arbitrary trusted memory overwrite vulnerability.

What is CVE-2020-8904?

CVE-2020-8904 is an arbitrary memory overwrite vulnerability in Asylo versions prior to 0.6.0. The issue arises due to a lack of validation in the ecall_restore function, enabling attackers to write to arbitrary locations in the enclave memory.

The Impact of CVE-2020-8904

The vulnerability has a CVSS base score of 6.4, indicating a medium severity issue. It has a high impact on availability but does not affect confidentiality. Attack complexity is high, and the attack vector is local.

Technical Details of CVE-2020-8904

Asylo version 0.6.0 and earlier are susceptible to this vulnerability.

Vulnerability Description

The vulnerability stems from the ecall_restore function's failure to validate the output_len pointer's range, allowing attackers to overwrite trusted memory.

Affected Systems and Versions

Product: Asylo
Vendor: Google LLC
Versions affected: < 0.6.0 (stable)

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the tmp_output_len value to write to arbitrary locations in the enclave memory.

Mitigation and Prevention

It is crucial to take immediate steps to address and prevent the exploitation of CVE-2020-8904.

Immediate Steps to Take

Update Asylo to version 0.6.0 or later to mitigate the vulnerability.

Long-Term Security Practices

Regularly monitor and update software to patch known vulnerabilities.
Implement secure coding practices to prevent memory-related vulnerabilities.

Patching and Updates

Apply patches and updates provided by the vendor to ensure system security.