EUVD-2024-52312

Comprehensive Technical Analysis of EUVD-2024-52312

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Description: The vulnerability in openwrt/asu involves a flaw in the request hashing mechanism, which truncates SHA-256 hashes to only 12 characters. This truncation significantly reduces the entropy of the hashes, making it feasible for attackers to generate hash collisions. By exploiting this weakness, an attacker can serve a previously built malicious image in place of a legitimate one, thereby poisoning the artifact cache and delivering compromised images to unsuspecting users.

Severity Evaluation: The Base Score of 9.3 (CVSS:4.0) indicates a critical vulnerability. The scoring vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N highlights the following:

• Attack Vector (AV): Network (N) - The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low (L) - The attack requires minimal skill or resources.
• Authentication (AT): None (N) - No authentication is required to exploit the vulnerability.
• Privileges Required (PR): None (N) - No special privileges are needed.
• User Interaction (UI): None (N) - No user interaction is required.
• Confidentiality (VC): High (H) - The vulnerability can lead to significant loss of confidentiality.
• Integrity (VI): High (H) - The vulnerability can lead to significant loss of integrity.
• Availability (VA): High (H) - The vulnerability can lead to significant loss of availability.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

1. Hash Collision Attack: An attacker can generate a hash collision by exploiting the truncated SHA-256 hashes, allowing them to serve malicious images.
2. Command Injection: The vulnerability can be combined with a command injection flaw in Imagebuilder, enabling attackers to inject arbitrary commands into the build process.
3. Supply Chain Attack: By poisoning the artifact cache, attackers can distribute compromised firmware images signed with legitimate build keys, affecting downstream users.

Exploitation Methods:

1. Hash Collision Generation: Attackers can use computational resources to generate hash collisions due to the reduced entropy of the truncated hashes.
2. Malicious Image Distribution: Once a collision is generated, attackers can serve malicious images that appear legitimate.
3. Command Injection: Attackers can inject malicious commands during the build process, leading to the production of compromised firmware images.

3. Affected Systems and Software Versions

Affected Systems:

• OpenWrt-based distributions using the openwrt/asu image on demand server.

Software Versions:

• All versions of openwrt/asu prior to the patch commit 920c8a1.

4. Recommended Mitigation Strategies

1. Patch Deployment:

   • Apply the patch 920c8a1 to the openwrt/asu server to fix the hashing mechanism and prevent hash collisions.

2. Hash Length Verification:

   • Ensure that the SHA-256 hashes are not truncated and maintain their full length to preserve entropy.

3. Code Review and Auditing:

   • Conduct a thorough code review and security audit of the openwrt/asu server and related components to identify and mitigate similar vulnerabilities.

4. Monitoring and Logging:

   • Implement robust monitoring and logging mechanisms to detect and respond to any suspicious activities or anomalies in the build process.

5. User Education:

   • Educate users about the risks of using compromised firmware images and the importance of verifying the integrity of downloaded images.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to the European cybersecurity landscape, particularly for organizations and individuals relying on OpenWrt-based distributions. The potential for widespread distribution of compromised firmware images can lead to:

• Compromised Network Devices: Routers and other network devices running compromised firmware can be used for further attacks, data exfiltration, or unauthorized access.
• Supply Chain Disruption: The integrity of the software supply chain is compromised, affecting downstream users and partners.
• Regulatory Compliance: Organizations may face regulatory penalties and reputational damage due to the breach of data protection and cybersecurity regulations.

6. Technical Details for Security Professionals

Technical Analysis:

• Hash Truncation Issue: The truncation of SHA-256 hashes to 12 characters reduces the effective entropy from 256 bits to approximately 60 bits, making hash collisions computationally feasible.
• Command Injection Flaw: The command injection vulnerability in Imagebuilder allows attackers to inject arbitrary commands, leading to the production of malicious firmware images.
• Patch Details: The patch 920c8a1 addresses the hashing mechanism flaw by ensuring that SHA-256 hashes are not truncated, thereby preserving their full entropy.

References:

• GitHub Security Advisory
• Patch Commit

Conclusion: The vulnerability in openwrt/asu is critical and requires immediate attention. Organizations using OpenWrt-based distributions should apply the patch and implement additional security measures to mitigate the risk of hash collision attacks and command injection. The European cybersecurity community should remain vigilant and proactive in addressing similar vulnerabilities to ensure the integrity and security of the software supply chain.