CVE-2015-5159 in python-kdcproxy
Summary
by MITRE
python-kdcproxy before 0.3.2 allows remote attackers to cause a denial of service via a large POST request.
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Analysis
by VulDB Data Team • 06/03/2023
The vulnerability identified as CVE-2015-5159 affects the python-kdcproxy software version 0.3.1 and earlier, representing a denial of service condition that can be exploited by remote attackers through the submission of oversized POST requests. This issue specifically targets the request handling mechanism within the kdcproxy component, which serves as a proxy for kerberos authentication requests in python-based environments.
The technical flaw stems from inadequate input validation and resource management within the POST request processing pipeline. When the system receives a large POST request, it fails to properly handle the excessive data size, leading to resource exhaustion or memory allocation failures that ultimately result in service unavailability. This type of vulnerability falls under the category of insufficient input validation as classified by CWE-20, where the application does not adequately validate the size or content of incoming data requests.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to systematically degrade system availability through resource exhaustion attacks. Remote exploitation means that attackers do not require physical access or local privileges to execute the attack, making it particularly dangerous in networked environments where the proxy service is exposed to external traffic. The vulnerability can be classified under ATT&CK technique T1499.004 for network denial of service, where adversaries consume system resources to prevent legitimate use of services.
The vulnerability demonstrates poor resource management practices in the application's request handling code, where memory allocation occurs without proper bounds checking or size limitations. This creates an attack surface where malicious actors can submit requests containing excessive data payloads that overwhelm the system's ability to process them. The lack of rate limiting or request size constraints in the proxy implementation allows for straightforward exploitation without requiring advanced attack techniques or specialized tools.
Mitigation strategies should focus on implementing proper input validation and request size limiting mechanisms within the kdcproxy software. Upgrading to version 0.3.2 or later resolves the issue through improved request handling and resource management. Additional defensive measures include implementing rate limiting on incoming requests, setting maximum request size thresholds, and configuring appropriate resource allocation limits. Network-level protections such as firewalls or load balancers can also be configured to filter or limit request sizes before they reach the vulnerable application, providing an additional layer of defense against such denial of service attacks.
The vulnerability highlights the importance of proper resource management in web applications and the need for robust input validation practices. Organizations should implement comprehensive security testing procedures that include load testing and stress testing to identify potential resource exhaustion vulnerabilities. Regular security updates and patch management programs become critical in maintaining system integrity against known vulnerabilities like CVE-2015-5159. The issue also underscores the necessity of following secure coding practices that prevent buffer overflows and resource exhaustion conditions in network services that handle user input.