CVE-2018-11367 in CppCMS
Summary
by MITRE
An issue was discovered in CppCMS before 1.2.1. There is a denial of service in the JSON parser module.
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Analysis
by VulDB Data Team • 02/08/2020
The vulnerability identified as CVE-2018-11367 represents a critical denial of service weakness within the CppCMS web application framework version 1.2.0 and earlier. This issue specifically affects the JSON parser module, which is a fundamental component responsible for processing structured data exchanged between web applications and their clients. CppCMS, being a high-performance web framework written in C++, relies heavily on proper JSON parsing for handling API requests and data serialization. The flaw manifests when the framework encounters malformed or specially crafted JSON input that triggers an unexpected behavior in the parser implementation.
The technical root cause of this vulnerability lies in inadequate input validation and error handling within the JSON parsing logic. When the parser encounters malformed JSON data, it fails to properly handle the error conditions, leading to a system crash or resource exhaustion that effectively renders the web application unavailable to legitimate users. This behavior aligns with CWE-400, which categorizes improper handling of exceptional conditions as a weakness that can lead to denial of service attacks. The vulnerability exploits the parser's inability to gracefully manage malformed input sequences, causing the application to enter an unrecoverable state where it cannot process subsequent requests properly.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by malicious actors to perform systematic denial of service attacks against CppCMS applications. Attackers can craft specific JSON payloads that, when processed by the vulnerable parser, will cause the web server to crash or become unresponsive, potentially affecting multiple concurrent users. This weakness is particularly concerning in production environments where CppCMS applications serve critical business functions, as the attack can be executed with minimal resources and can cause significant downtime. The vulnerability affects applications that utilize the framework's JSON handling capabilities, which is common in RESTful APIs and web services that require structured data exchange. According to ATT&CK framework reference T1499.004, this vulnerability can be categorized under the disruption of services technique, where attackers leverage application-level weaknesses to deny access to legitimate users.
Mitigation strategies for CVE-2018-11367 primarily focus on upgrading to CppCMS version 1.2.1 or later, which contains the necessary patches to address the JSON parser flaw. Organizations should also implement input validation measures at the application level, including sanitizing all JSON data before it reaches the parser module. Network-level protections such as rate limiting and content filtering can help reduce the impact of potential attacks by limiting the volume of requests that can be processed by vulnerable applications. Additionally, implementing proper error handling and logging mechanisms can help detect exploitation attempts and provide visibility into attack patterns. Security monitoring should include checks for unusual resource consumption patterns that might indicate successful exploitation attempts. The vulnerability demonstrates the importance of robust input validation and error handling in web frameworks, as highlighted by security best practices in the OWASP Top Ten and similar industry standards that emphasize the need for proper sanitization of all external inputs to prevent various forms of injection attacks and service disruption.