Critical Flaw in Nuclei Scanner Enables Code Execution
High-Severity Vulnerability Discovered in Nuclei Vulnerability Scanner: What You Need to Know
A recently disclosed high-severity security flaw in ProjectDiscovery’s Nuclei vulnerability scanner has raised alarms in the cybersecurity community. This flaw, tracked as CVE-2024-43405, poses a significant risk to users as it allows attackers to bypass signature checks, potentially enabling the execution of malicious code. With a CVSS score of 7.4 out of 10, it affects all versions of Nuclei released after 3.0.0, highlighting the need for urgent attention and updates.
Understanding the Nuclei Vulnerability
The vulnerability in Nuclei originates from a critical discrepancy in how the signature verification process interacts with the YAML parser. Specifically, the issue arises when newline characters are processed differently, allowing attackers to inject harmful content into templates while still maintaining a valid signature for the non-malicious parts. This manipulation opens the door for executing arbitrary code on the host system.
Key Details About CVE-2024-43405
- Vulnerability Tracking: CVE-2024-43405
- CVSS Score: 7.4
- Impacted Versions: All Nuclei versions post 3.0.0
- Potential Risks:
- Execution of arbitrary code
- Access to sensitive data
- System compromise
Wiz, the cloud security firm that uncovered this vulnerability, emphasized that the flaw is deeply rooted in the template signature verification process, which is crucial for ensuring the integrity of templates from the official repository.
How the Exploit Works
The issue is mainly linked to the use of regular expressions for signature validation. By exploiting inconsistencies between regex and YAML parsing, attackers can introduce a "\r" character that bypasses regex checks, leading to potentially malicious code execution. Wiz researcher Guy Goldenberg explained that while the verification only validates the first "# digest:" line, subsequent lines can be ignored during verification yet still executed.
Recommendations for Nuclei Users
To mitigate the risks associated with CVE-2024-43405, Nuclei users should take the following steps:
- Update Immediately: Ensure you are running the latest version of Nuclei (currently 3.3.7) to protect against this vulnerability.
- Validate Templates: Avoid running untrusted or community-contributed templates without proper validation and isolation to reduce exposure to potential attacks.
- Monitor Security Updates: Stay informed about updates and patches from ProjectDiscovery to maintain system integrity.
Conclusion
The discovery of CVE-2024-43405 in the Nuclei vulnerability scanner serves as a stark reminder of the importance of robust security practices in software development and usage. By remaining vigilant and proactive, organizations can mitigate the risks associated with this significant flaw.
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