CVE-2017-16138 in mime Module
Summary
by MITRE
The mime module is vulnerable to regular expression denial of service when a mime lookup is performed on untrusted user input.
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Analysis
by VulDB Data Team • 03/21/2023
The CVE-2017-16138 vulnerability resides within the mime module, a critical component in web applications that handles content type detection for files and data streams. This module is widely used across Node.js applications to determine the appropriate MIME type based on file extensions or content, making it a common target for attackers seeking to disrupt application functionality. The vulnerability manifests when the module processes untrusted user input through its lookup mechanism, creating a potential attack vector that can be exploited to cause service disruption.
The technical flaw stems from the module's implementation of regular expressions used during MIME type resolution. When malicious input is provided, specifically crafted strings that trigger catastrophic backtracking in the regular expression engine, the processing time becomes exponentially increased. This behavior occurs because the regular expressions contain nested quantifiers that create a combinatorial explosion of possible matching paths, causing the system to consume excessive CPU resources and potentially leading to complete service unavailability.
This vulnerability directly maps to CWE-400, which describes unrestricted input validation leading to denial of service conditions. The attack pattern aligns with the ATT&CK technique T1499.004, specifically targeting network denial of service through resource exhaustion. The operational impact is significant as it can be exploited by remote attackers to perform denial of service attacks against applications using the vulnerable module, potentially affecting availability for legitimate users while consuming system resources and potentially causing application crashes or timeouts.
The exploitation requires minimal technical skill and can be automated, making it particularly dangerous in production environments where the mime module is commonly used for file upload validation, content negotiation, or HTTP header processing. Organizations using vulnerable versions of the mime module face risks of service disruption, increased resource consumption, and potential denial of service conditions that can impact business operations and user experience.
Mitigation strategies include updating to patched versions of the mime module where the regular expressions have been optimized to prevent catastrophic backtracking scenarios. Additionally, implementing input validation and sanitization measures can help reduce the risk of exploitation by limiting the complexity of input processed by the module. Organizations should also consider implementing rate limiting and monitoring for unusual processing patterns that might indicate exploitation attempts. The vulnerability highlights the importance of regular security updates and thorough testing of third-party dependencies to prevent such issues from compromising system availability and stability.