CVE-2023-40586 in OWASP Coraza WAF
Summary
by MITRE • 08/26/2023
OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. Due to the misuse of `log.Fatalf`, the application using coraza crashed after receiving crafted requests from attackers. The application will immediately crash after receiving a malicious request that triggers an error in `mime.ParseMediaType`. This issue was patched in version 3.0.1.
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Analysis
by VulDB Data Team • 08/26/2023
The vulnerability identified as CVE-2023-40586 affects OWASP Coraza WAF, a go language library designed to provide web application firewall capabilities compatible with ModSecurity. This security library serves as a critical defense mechanism for web applications by filtering and monitoring HTTP requests. The flaw manifests in how the library handles error conditions during MIME media type parsing operations, creating a potential denial of service scenario that could be exploited by remote attackers.
The technical root cause of this vulnerability stems from the improper use of `log.Fatalf` within the Coraza WAF implementation. When processing maliciously crafted HTTP requests that trigger errors in the `mime.ParseMediaType` function, the application does not handle these exceptions gracefully. Instead of logging the error and continuing normal operation, the library invokes `log.Fatalf` which terminates the entire application process immediately. This represents a fundamental flaw in error handling design that violates established principles of robust software engineering and fault tolerance.
The operational impact of this vulnerability is significant for any application that relies on Coraza WAF for protection. Attackers can exploit this weakness by crafting specific HTTP requests that contain malformed MIME media type headers or content. Upon receiving such requests, the WAF process crashes completely, resulting in immediate service disruption for the protected web application. This creates a denial of service condition that can be easily exploited without requiring authentication or specialized privileges, making it particularly dangerous in production environments where availability is critical.
This vulnerability aligns with CWE-470, which addresses the use of insecure functions that can lead to program termination, and relates to the broader category of improper error handling patterns that can result in system instability. From an ATT&CK framework perspective, this issue maps to the T1499.004 technique related to network denial of service attacks through application layer attacks, and could potentially support broader reconnaissance activities by providing attackers with information about the application's error handling mechanisms. The flaw also demonstrates a lack of proper input validation and error recovery procedures that are essential for maintaining system resilience. Organizations using affected versions of Coraza WAF should immediately upgrade to version 3.0.1 or later to mitigate this risk, as the patch addresses the improper error handling by implementing graceful degradation rather than application termination.