CVE-2021-28099 : Exploit Details and Defense Strategies

Netflix OSS Hollow is affected by a vulnerability that allows an attacker to pre-create directories with wide permissions due to a flaw in Files.exists(parent) and the use of insecure randomness for file names.

Understanding CVE-2021-28099

This CVE relates to a Local Information Disclosure vulnerability in Netflix OSS Hollow.

What is CVE-2021-28099?

CVE-2021-28099 is a security flaw in Netflix OSS Hollow that enables an attacker to pre-create directories with broad permissions, leveraging a weakness in Files.exists(parent) and the predictable nature of file names due to the use of insecure randomness.

The Impact of CVE-2021-28099

This vulnerability could lead to local information disclosure, allowing malicious actors to potentially access sensitive data stored within the affected system.

Technical Details of CVE-2021-28099

The technical details of CVE-2021-28099 include:

Vulnerability Description

The flaw in Files.exists(parent) allows attackers to create directories with wide permissions, combined with the deterministic calculation of file names due to insecure randomness.

Affected Systems and Versions

All versions of Netflix OSS Hollow are impacted by this vulnerability.

Exploitation Mechanism

By exploiting the flawed Files.exists(parent) function and insecure randomness for file name generation, threat actors can disclose local information.

Mitigation and Prevention

To address CVE-2021-28099, consider the following steps:

Immediate Steps to Take

Update Netflix OSS Hollow to the latest version to mitigate the vulnerability.
Restrict directory creation permissions to prevent unauthorized access.

Long-Term Security Practices

Regularly monitor directories and file permissions within the application for any unusual changes.
Implement secure random number generation methods for file names.

Patching and Updates

Stay informed about security updates from Netflix to promptly apply patches and address any newly discovered vulnerabilities.