CVE-2016-15015 in Barzahlen Payment Module PHP SDK
Summary
by MITRE • 01/09/2023
A vulnerability, which was classified as problematic, was found in viafintech Barzahlen Payment Module PHP SDK up to 2.0.0. Affected is the function verify of the file src/Webhook.php. The manipulation leads to observable timing discrepancy. Upgrading to version 2.0.1 is able to address this issue. The name of the patch is 3e7d29dc0ca6c054a6d6e211f32dae89078594c1. It is recommended to upgrade the affected component. VDB-217650 is the identifier assigned to this vulnerability.
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Analysis
by VulDB Data Team • 01/30/2023
The vulnerability identified as CVE-2016-15015 represents a timing attack susceptibility within the viafintech Barzahlen Payment Module PHP SDK, specifically affecting versions up to 2.0.0. This security flaw manifests in the verify function of the src/Webhook.php file, where the implementation exhibits observable timing discrepancies that can be exploited by malicious actors. The timing discrepancy occurs when the system processes verification requests, creating measurable differences in response times that can reveal sensitive information about the verification process. Such vulnerabilities fall under the category of timing attacks as classified by CWE-347, which specifically addresses weaknesses in cryptographic implementations where timing information can be used to infer secret values or system behavior. The vulnerability is particularly concerning in payment processing environments where the integrity of verification mechanisms is paramount for preventing fraudulent transactions and maintaining system security.
The technical implementation flaw in the verify function demonstrates a classic timing attack vector where the system's response time varies based on the input validation process. When processing webhook verifications, the function's execution time correlates with the correctness of the verification data, creating a side-channel attack surface. This timing discrepancy allows attackers to perform statistical analysis on response times to deduce information about the verification process, potentially leading to successful exploitation of the payment module's security controls. The vulnerability's impact extends beyond simple information disclosure as it can enable attackers to bypass authentication mechanisms or manipulate payment verification workflows. The timing variations are particularly pronounced during cryptographic operations or when comparing sensitive data, making this a significant concern for payment processing systems where security is critical.
The operational impact of this vulnerability poses serious risks to payment processing systems that rely on the Barzahlen Payment Module PHP SDK. Attackers could potentially exploit the timing discrepancies to gain unauthorized access to payment verification processes, leading to fraudulent transactions or system compromise. The vulnerability's nature makes it particularly dangerous in high-volume payment environments where timing variations can be more easily detected and analyzed through statistical methods. Organizations using affected versions of the SDK face potential financial losses, regulatory compliance issues, and reputational damage if exploited successfully. The timing attack vector represents a sophisticated approach to bypassing security controls, as it leverages the natural behavior of the system rather than attempting direct exploitation of code vulnerabilities. This makes detection and mitigation more challenging as the attack operates within normal system behavior patterns.
The recommended mitigation strategy involves upgrading to version 2.0.1 of the Barzahlen Payment Module PHP SDK, which contains the patch 3e7d29dc0ca6c054a6d6e211f32dae89078594c1 addressing the timing discrepancy issue. This upgrade represents a direct fix to the verify function in src/Webhook.php, ensuring that response times remain consistent regardless of input validation outcomes. Organizations should implement this upgrade immediately and verify that all payment processing systems utilizing the SDK are updated to prevent exploitation. The patch addresses the core timing attack vector by implementing constant-time comparison algorithms that eliminate the observable timing discrepancies. Additionally, security teams should conduct thorough testing of the upgraded systems to ensure that the timing attack surface has been eliminated and that normal payment processing functionality remains intact. This vulnerability highlights the importance of implementing proper timing attack defenses in cryptographic implementations and demonstrates how seemingly minor implementation details can create significant security risks in payment processing systems. The remediation process should also include monitoring for any unusual timing patterns that might indicate continued vulnerability or other security issues within the payment infrastructure.