CVE-2017-16013 in Hapi
Summary
by MITRE
hapi is a web and services application framework. When hapi >= 15.0.0 <= 16.1.0 encounters a malformed `accept-encoding` header an uncaught exception is thrown. This may cause hapi to crash or to hang the client connection until the timeout period is reached.
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Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2017-16013 affects the hapi web and services application framework, specifically impacting versions between 15.0.0 and 16.1.0. This issue represents a classic input validation flaw that demonstrates poor error handling in HTTP header processing. The vulnerability manifests when the framework encounters a malformed accept-encoding header during HTTP request processing, leading to an uncaught exception that disrupts normal application operation. The accept-encoding header is a standard HTTP header used to indicate which content encodings the client can understand, making this vulnerability particularly concerning as it can be triggered by any client attempting to communicate with the affected server.
The technical flaw stems from inadequate parsing and validation of the accept-encoding header value within hapi's request handling pipeline. When a malformed header is processed, the framework fails to properly catch and handle the resulting exception, causing the application to either crash entirely or hang the client connection indefinitely. This behavior creates a denial of service condition that can be exploited by malicious actors to disrupt service availability. The vulnerability operates at the application layer and can be classified under CWE-248, which addresses "Uncaught Exception" conditions in software systems. The root cause lies in the framework's failure to implement proper exception handling mechanisms for malformed HTTP headers, which is a fundamental security principle that should be enforced in all web application frameworks.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors. When hapi applications crash due to malformed headers, attackers can repeatedly exploit this weakness to cause persistent service outages, effectively creating a denial of service condition that can be difficult to distinguish from legitimate traffic spikes. The hanging connection behavior further compounds the issue by consuming server resources and potentially leading to resource exhaustion attacks. From an attacker perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network disruption through resource exhaustion, and can be leveraged as part of broader attack campaigns targeting availability. The vulnerability affects any application using the affected hapi versions and can be exploited without requiring authentication or specialized privileges, making it particularly dangerous in production environments.
Mitigation strategies for this vulnerability should include immediate patching to versions of hapi that have addressed the issue, as well as implementing additional defensive measures. Organizations should deploy proper input validation at the application level and consider implementing rate limiting and connection timeout configurations to minimize the impact of potential exploitation attempts. Network-level protections such as web application firewalls can help detect and block malformed headers before they reach the vulnerable framework. The fix typically involves enhancing exception handling within the HTTP header parsing logic to gracefully manage malformed inputs rather than allowing them to propagate to unhandled exceptions. Security monitoring should be implemented to detect unusual patterns of connection hangs or application crashes that might indicate exploitation attempts. Additionally, organizations should conduct regular vulnerability assessments to identify other potential input validation issues within their application frameworks and ensure proper error handling practices are implemented across all components.