CVE-2021-43954 : Exploit Details and Defense Strategies

Fisheye and Crucible before 4.8.9 allow remote attackers to enumerate internal resources via SSRF.

Understanding CVE-2021-43954

The vulnerability in Fisheye and Crucible versions prior to 4.8.9 enables attackers with specific permissions to discover network and filesystem resources.

What is CVE-2021-43954?

The DefaultRepositoryAdminService class in Fisheye and Crucible before version 4.8.9 allows remote attackers, with 'can add repository permission,' to identify internal network and filesystem resources, exploiting a Server-Side Request Forgery (SSRF) vulnerability.

The Impact of CVE-2021-43954

Attackers with the necessary permissions can identify sensitive internal resources.
Potential information disclosure may lead to further targeted attacks.

Technical Details of CVE-2021-43954

Focusing on the technical aspects of the CVE.

Vulnerability Description

The SSRF vulnerability in Fisheye and Crucible versions less than 4.8.9 allows unauthorized access to internal resources.

Affected Systems and Versions

Product: Fisheye
Vendor: Atlassian
Versions Affected: Less than 4.8.9
Product: Crucible
Vendor: Atlassian
Versions Affected: Less than 4.8.9

Exploitation Mechanism

The vulnerability arises from insufficient input validation in the DefaultRepositoryAdminService class, enabling attackers to probe for internal resources.

Mitigation and Prevention

Guidance on addressing the CVE and preventing exploitation.

Immediate Steps to Take

Upgrade Fisheye and Crucible to version 4.8.9 or higher.
Restrict repository management permissions to authorized personnel.

Long-Term Security Practices

Regularly review and update access controls and permissions.
Conduct security trainings to educate users on SSRF and other exploitation techniques.

Patching and Updates

Apply vendor-released patches promptly to mitigate the SSRF vulnerability in Fisheye and Crucible.