CVE-2018-25079 in is-url
Summary
by MITRE • 02/04/2023
A vulnerability was found in Segmentio is-url up to 1.2.2. It has been rated as problematic. Affected by this issue is some unknown functionality of the file index.js. The manipulation leads to inefficient regular expression complexity. The attack may be launched remotely. Upgrading to version 1.2.3 is able to address this issue. The name of the patch is 149550935c63a98c11f27f694a7c4a9479e53794. It is recommended to upgrade the affected component. VDB-220058 is the identifier assigned to this vulnerability.
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Analysis
by VulDB Data Team • 03/04/2023
The vulnerability identified as CVE-2018-25079 affects the Segmentio is-url library version 1.2.2 and earlier, representing a critical security flaw that exposes applications utilizing this component to potential denial of service attacks. This issue resides within the index.js file of the library and manifests through inefficient regular expression complexity that can be exploited remotely. The vulnerability falls under the category of regular expression denial of service (ReDoS) as classified by CWE-1321, where malicious input can cause exponential backtracking in regular expression engines, leading to system resource exhaustion and application unresponsiveness. The attack vector is particularly concerning as it can be executed remotely without requiring authentication, making it accessible to any attacker who can influence input to the vulnerable library.
The technical implementation of this vulnerability stems from poorly constructed regular expressions within the is-url library that fail to account for catastrophic backtracking scenarios. When processing certain malformed URLs or input strings, the regular expressions employed in the index.js file can experience exponential time complexity, causing the application to hang or consume excessive CPU resources. This behavior directly aligns with the ATT&CK technique T1496 for resource exhaustion attacks, where adversaries leverage software vulnerabilities to consume system resources. The specific patch referenced in the advisory uses the commit identifier 149550935c63a98c11f27f694a7c4a9479e53794 to address the issue by implementing more efficient regular expression patterns that prevent catastrophic backtracking scenarios.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially compromising application availability and user experience. Applications that rely on the is-url library for URL validation and processing become susceptible to denial of service conditions where legitimate requests can be delayed or rejected due to the inefficient regular expression processing. This vulnerability affects web applications, APIs, and services that process user input through URL validation mechanisms, creating a potential attack surface where adversaries can craft malicious input to trigger resource exhaustion. The remediation strategy involves upgrading to version 1.2.3 of the is-url library, which implements improved regular expression patterns that eliminate the vulnerability while maintaining the library's core functionality. Organizations should conduct thorough testing of their applications after upgrading to ensure compatibility and verify that the vulnerability has been effectively mitigated.
Security practitioners should consider this vulnerability as part of broader application security testing protocols, particularly when evaluating third-party libraries and dependencies. The vulnerability demonstrates the importance of regular dependency updates and security monitoring, as it represents a common class of flaws that can be systematically addressed through proper vulnerability management processes. The issue also highlights the necessity of input validation testing and the importance of understanding how regular expressions are used within applications, particularly in validation and parsing functions. Organizations implementing security controls should consider monitoring for similar patterns in their codebases and conducting regular security assessments of their dependency tree to identify and remediate similar vulnerabilities before they can be exploited in production environments.