CVE-2017-0907 in Recurly Client .NET Library
Summary
by MITRE
The Recurly Client .NET Library before 1.0.1, 1.1.10, 1.2.8, 1.3.2, 1.4.14, 1.5.3, 1.6.2, 1.7.1, 1.8.1 is vulnerable to a Server-Side Request Forgery vulnerability due to incorrect use of "Uri.EscapeUriString" that could result in compromise of API keys or other critical resources.
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Analysis
by VulDB Data Team • 01/10/2023
The CVE-2017-0907 vulnerability represents a critical server-side request forgery flaw in the Recurly Client .NET Library across multiple version ranges, demonstrating a fundamental security oversight in URI handling mechanisms. This vulnerability specifically arises from the improper utilization of the Uri.EscapeUriString method within the library's implementation, creating a pathway for malicious actors to manipulate API requests and potentially access sensitive resources. The flaw exists in the library's processing of external inputs that are subsequently used to construct HTTP requests, making it particularly dangerous in environments where the library handles untrusted data from users or external systems.
The technical root cause of this vulnerability lies in the inadequate validation and sanitization of URI components within the library's request construction process. When the library processes user-provided data or external inputs to build API requests, it relies on Uri.EscapeUriString for encoding purposes, but fails to properly account for the complete URI structure. This incorrect approach allows attackers to craft malicious inputs that can bypass the intended security boundaries, effectively enabling them to redirect requests to unintended destinations. The vulnerability specifically manifests when the library constructs URLs using unvalidated user input, where the URI encoding mechanism does not adequately prevent path traversal or domain redirection attacks. This behavior aligns with CWE-918, which describes server-side request forgery vulnerabilities that occur when applications fail to properly validate and sanitize user-provided URLs or URI components.
The operational impact of this vulnerability extends beyond simple data exposure, as it creates potential pathways for complete API key compromise and unauthorized access to critical resources within the Recurly ecosystem. Attackers who exploit this vulnerability can potentially redirect API requests to malicious endpoints, intercept sensitive data, or gain unauthorized access to customer information and payment processing capabilities. The vulnerability affects multiple version ranges of the library, indicating a prolonged period where the security flaw remained undetected and potentially exploited by adversaries. This widespread impact across several major version releases suggests that organizations using affected versions of the Recurly Client .NET Library may have been exposed to significant security risks for an extended period, particularly in environments where the library processes untrusted inputs from external sources.
Organizations utilizing the affected Recurly Client .NET Library versions should prioritize immediate remediation through patching to version 1.0.1, 1.1.10, 1.2.8, 1.3.2, 1.4.14, 1.5.3, 1.6.2, 1.7.1, or 1.8.1, as these releases contain the necessary fixes for the URI handling vulnerability. The mitigation strategy should also include comprehensive code review of any custom implementations that utilize the library, ensuring proper input validation and URI sanitization practices are implemented. Security teams should conduct thorough assessments of systems that may have been exposed to this vulnerability, particularly focusing on monitoring for unauthorized API access patterns or suspicious request redirections. Additionally, implementing network-level controls such as outbound traffic filtering and API gateway protections can provide additional defense-in-depth measures against potential exploitation attempts. The vulnerability's classification under ATT&CK technique T1190, which covers proxy usage for lateral movement, highlights the potential for attackers to leverage this flaw as part of broader attack campaigns targeting cloud-based payment processing systems and customer data repositories.