CVE-2019-9656 in LibOFX
Summary
by MITRE • 01/25/2023
An issue was discovered in LibOFX 0.9.14. There is a NULL pointer dereference in the function OFXApplication::startElement in the file lib/ofx_sgml.cpp, as demonstrated by ofxdump.
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability identified as CVE-2019-9656 represents a critical null pointer dereference flaw within the LibOFX 0.9.14 library, specifically within the OFXApplication::startElement function located in lib/ofx_sgml.cpp. This issue manifests when processing malformed OFX (Open Financial Exchange) files through the ofxdump utility, creating a potential denial of service condition that could be exploited by malicious actors. The vulnerability stems from inadequate input validation and error handling within the SGML parsing functionality that LibOFX employs to process financial data formats.
The technical implementation of this flaw occurs when the OFXApplication::startElement function attempts to dereference a null pointer during the parsing of OFX documents. This function is responsible for handling the start of elements within the SGML structure, and the absence of proper null checks before pointer operations creates an exploitable condition. When an attacker supplies a crafted OFX file containing malformed SGML elements, the parsing routine fails to validate the pointer state before accessing it, resulting in a segmentation fault or crash that terminates the application process. This behavior aligns with CWE-476 which specifically addresses null pointer dereference vulnerabilities, and the issue demonstrates characteristics consistent with CWE-125 which covers out-of-bounds read conditions.
The operational impact of CVE-2019-9656 extends beyond simple application crashes to encompass broader security implications for financial data processing systems. Organizations relying on LibOFX for OFX file handling and processing may experience service disruption when malicious or malformed files are processed through the ofxdump utility or other applications utilizing the vulnerable library. The vulnerability affects systems where OFX files are automatically processed or where user-provided financial data is parsed without proper sanitization, potentially creating opportunities for denial of service attacks against financial institutions, accounting systems, or any platform handling OFX formatted financial information. This vulnerability could be particularly dangerous in automated processing environments where multiple OFX files are processed sequentially.
Mitigation strategies for this vulnerability require immediate attention through library updates and proper input validation implementation. The primary remediation involves upgrading to a patched version of LibOFX that addresses the null pointer dereference issue within the OFXApplication::startElement function. System administrators should also implement strict input validation procedures for all OFX files before processing, including file format verification and content sanitization. Additionally, implementing proper error handling and exception management within applications that utilize LibOFX can help prevent the crash conditions from occurring. Organizations should consider deploying defensive measures such as sandboxed processing environments for OFX file analysis and monitoring for unusual processing patterns that might indicate exploitation attempts. The vulnerability demonstrates characteristics that align with ATT&CK technique T1499.004 which covers network disruption, and organizations should treat this as a potential vector for service availability attacks against financial processing systems.