CVE-2024-23838 in TrueLayer
Summary
by MITRE • 01/30/2024
TrueLayer.NET is the .Net client for TrueLayer. The vulnerability could potentially allow a malicious actor to gain control over the destination URL of the HttpClient used in the API classes. For applications using the SDK, requests to unexpected resources on local networks or to the internet could be made which could lead to information disclosure. The issue can be mitigated by having strict egress rules limiting the destinations to which requests can be made, and applying strict validation to any user input passed to the `truelayer-dotnet` library. Versions of TrueLayer.Client `v1.6.0` and later are not affected.
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Analysis
by VulDB Data Team • 02/22/2024
The vulnerability identified as CVE-2024-23838 affects the TrueLayer.NET client library, specifically targeting the handling of HTTP client destination URLs within API classes. This issue represents a significant security concern as it allows potential manipulation of the target endpoints that HTTP requests are directed to, creating pathways for unauthorized network access and data exfiltration. The flaw exists in the library's implementation where user-provided input can influence the destination URL of HttpClient instances, potentially enabling attackers to redirect requests to unintended targets including internal network resources or external malicious servers.
The technical implementation flaw stems from inadequate input validation and URL construction within the SDK's HTTP client handling mechanisms. When applications utilizing the TrueLayer.Client library process user data or configuration parameters that are subsequently used to construct HTTP request destinations, the library fails to properly sanitize or validate these inputs before passing them to HttpClient. This vulnerability manifests as a path traversal or URL manipulation issue that can be exploited through crafted inputs that alter the intended destination of API requests. The flaw aligns with CWE-73, which addresses improper control of generation of code, and specifically relates to improper input validation in the context of URL handling and HTTP client configuration. The vulnerability creates opportunities for attackers to perform unauthorized network reconnaissance or data exfiltration by redirecting requests to internal systems that should remain protected.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential lateral movement within networks and unauthorized access to internal resources. Applications using the affected SDK versions may inadvertently make requests to internal services or systems that are not intended to be accessible through the API interface, creating attack vectors for reconnaissance and exploitation. The vulnerability particularly poses risks in environments where internal network resources are not properly segmented or where strict egress controls are not implemented. Attackers could leverage this issue to discover internal services, access sensitive data stored on internal systems, or potentially execute further attacks through compromised internal endpoints. This vulnerability also aligns with ATT&CK technique T1071.004 for application layer protocol tunneling and T1046 for network service scanning, as it enables unauthorized network access patterns that could be used for reconnaissance activities.
Mitigation strategies for CVE-2024-23838 must address both the immediate software vulnerability and implement broader network security controls. Organizations should immediately upgrade to TrueLayer.Client version v1.6.0 or later where the vulnerability has been resolved. Additionally, implementing strict egress firewall rules and network segmentation can significantly reduce the impact of this vulnerability by limiting which external destinations applications can reach. The implementation of strict input validation and sanitization within applications that use this library is crucial, particularly for any user-provided data that might influence HTTP request destinations. Security controls should include monitoring for unusual outbound network connections and implementing web application firewalls to detect and prevent malformed URL requests. The vulnerability demonstrates the importance of secure coding practices and input validation, particularly in libraries that handle network communications and HTTP client operations. Organizations should also conduct security assessments to identify any applications still using vulnerable versions of the library and ensure comprehensive testing of network access controls to prevent unauthorized resource access patterns that could result from this vulnerability.