CVE-2024-56476 in TXSeries for Multiplatforms
Summary
by MITRE • 04/02/2025
IBM TXSeries for Multiplatforms 9.1 and 11.1 could allow an attacker to enumerate usernames due to an observable login attempt response discrepancy.
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Analysis
by VulDB Data Team • 07/16/2025
IBM TXSeries for Multiplatforms version 9.1 and 11.1 contains a vulnerability that enables username enumeration through differential response analysis during authentication attempts. This flaw stems from the system's inconsistent handling of login requests where valid and invalid usernames produce distinguishable responses, creating a timing or content-based distinction that attackers can exploit to determine which usernames exist within the system. The vulnerability directly maps to CWE-203 Information Exposure Through Discrepancy, which occurs when systems provide different responses to similar inputs, thereby leaking information about internal state or configuration. Attackers can leverage this inconsistency to systematically test usernames and identify valid accounts through response analysis, effectively bypassing traditional account lockout mechanisms and brute force protections. The operational impact extends beyond simple credential theft as this vulnerability enables attackers to build comprehensive user dictionaries that can be used for subsequent attacks including privilege escalation, lateral movement, and targeted social engineering campaigns. The timing discrepancies in response handling create a predictable pattern that aligns with ATT&CK technique T1078 Valid Accounts, where adversaries seek to establish and maintain access using legitimate credentials. This vulnerability particularly affects environments where TXSeries serves as a transaction processing system for critical business applications, as the enumeration capability can be combined with other attack vectors to compromise entire transaction processing pipelines. The flaw represents a fundamental weakness in the authentication protocol implementation where the system fails to provide consistent response timing regardless of whether the username exists in the system. Organizations running these versions should consider immediate mitigation through response normalization, implementing constant-time authentication routines, and deploying additional monitoring to detect unusual authentication patterns. The vulnerability demonstrates the importance of applying the principle of least privilege in authentication systems and highlights how seemingly minor inconsistencies in system behavior can create significant security risks. Security teams should also implement account lockout policies with random delays and consider multi-factor authentication as additional safeguards against this type of credential enumeration attack. This issue affects both the 9.1 and 11.1 versions of the software, indicating it may have persisted across multiple releases, emphasizing the need for comprehensive patch management and security audits of legacy systems. The vulnerability's exploitation requires minimal technical skill and can be automated, making it particularly dangerous in environments where transaction processing systems handle sensitive financial or personal data. Organizations should also consider implementing network-based detection mechanisms that can identify patterns consistent with username enumeration attempts and establish monitoring procedures to detect unusual authentication activity that may indicate exploitation of this vulnerability.