CVE-2017-16111 in Content module
Summary
by MITRE
The content module is a module to parse HTTP Content-* headers. It is used by the hapijs framework to provide this functionality. The module is vulnerable to regular expression denial of service when passed a specifically crafted Content-Type or Content-Disposition header.
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Analysis
by VulDB Data Team • 02/16/2020
The vulnerability identified as CVE-2017-16111 resides within the content module of the hapijs framework, which serves as a critical component for parsing HTTP Content-* headers. This module operates as an essential middleware function that processes incoming HTTP requests and extracts header information to facilitate proper content handling within web applications. The security flaw manifests specifically when the module encounters malformed or specially crafted Content-Type or Content-Disposition headers that trigger problematic regular expression patterns during parsing operations.
The technical implementation of this vulnerability stems from the module's use of regular expressions that are susceptible to catastrophic backtracking when processing malicious input. When an attacker submits a crafted header containing specific patterns that cause the regular expression engine to perform exponential time complexity operations, the system experiences significant performance degradation leading to denial of service conditions. This behavior aligns with the common characteristics of regular expression denial of service vulnerabilities classified under CWE-400, where the input processing becomes computationally expensive and can effectively halt application responsiveness. The vulnerability is particularly concerning because it operates at the HTTP parsing layer, meaning any application using hapijs and processing user-provided headers becomes vulnerable to this attack vector.
The operational impact of CVE-2017-16111 extends beyond simple service disruption to potentially enable more sophisticated attack scenarios within the broader threat landscape. An attacker could leverage this vulnerability to perform resource exhaustion attacks against web applications, consuming CPU cycles and memory resources to the point where legitimate requests cannot be processed effectively. This vulnerability maps to ATT&CK technique T1499.004, which involves network disruption through resource exhaustion, and represents a significant risk to application availability. The attack surface is particularly broad since hapijs is widely adopted across various web applications and services, making this vulnerability potentially exploitable across numerous systems. Organizations using the framework without proper input validation or rate limiting mechanisms face elevated risk of experiencing service degradation or complete unavailability during sustained attacks.
Mitigation strategies for CVE-2017-16111 should focus on immediate patching of the affected module to address the regular expression patterns that cause the performance issues. System administrators and developers should update to the patched versions of the content module or the hapijs framework itself to eliminate the vulnerable code paths. Additionally, implementing proper input validation and sanitization at the application level can provide defense-in-depth measures against malformed headers that might not be caught by the patched module. Network-level protections such as rate limiting and header validation rules within reverse proxies or web application firewalls can help detect and block suspicious header patterns before they reach the vulnerable application components. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual processing times or resource consumption patterns that might indicate exploitation attempts. The remediation process must include thorough testing to ensure that the patch does not introduce compatibility issues with existing application functionality while maintaining the security posture against this specific denial of service vulnerability.