CVE-2017-2920 in LibOFX
Summary
by MITRE
An exploitable buffer overflow vulnerability exists in the tag parsing functionality of LibOFX 0.9.11. A specially crafted OFX file can cause a write out of bounds resulting in a buffer overflow on the stack. An attacker can construct a malicious OFX file to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/30/2022
The vulnerability identified as CVE-2017-2920 represents a critical buffer overflow flaw within LibOFX version 0.9.11, specifically within its tag parsing mechanisms. This issue manifests as a stack-based buffer overflow that occurs when processing specially crafted OFX (Open Financial Exchange) files, which are commonly used for financial data exchange between financial institutions and client applications. The vulnerability stems from insufficient input validation and boundary checking during the parsing of OFX file elements, creating an exploitable condition that can be leveraged by malicious actors to compromise systems running affected software.
The technical exploitation of this vulnerability involves the manipulation of OFX file structures to trigger an out-of-bounds write operation on the stack memory. When LibOFX processes malformed OFX tags containing excessive data or malformed structures, the parsing function fails to properly validate the buffer boundaries, allowing an attacker to write data beyond the allocated memory space. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and represents a classic example of improper input validation that enables arbitrary code execution. The attack vector requires the victim to open or process a maliciously crafted OFX file, making this a typical client-side exploitation scenario.
The operational impact of this vulnerability extends beyond simple denial of service, as it creates potential for remote code execution and system compromise. Attackers who can successfully exploit this vulnerability gain the ability to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise, data exfiltration, or persistent access. Given that OFX files are commonly used for financial transactions and sensitive data exchange, the implications of exploitation are particularly severe. The vulnerability affects any system that utilizes LibOFX 0.9.11 for processing financial data, including banking applications, financial management software, and any other systems that parse OFX formatted files.
Mitigation strategies for this vulnerability require immediate software updates to versions that address the buffer overflow condition through proper input validation and boundary checking. System administrators should prioritize patching affected installations and implement additional security measures such as input sanitization and file validation before processing any OFX files. The vulnerability aligns with ATT&CK technique T1059.007, which covers scripting languages for execution, as exploitation may involve the use of scripts to craft malicious OFX files. Organizations should also consider implementing network segmentation and file access controls to limit exposure, while monitoring for suspicious file processing activities that might indicate exploitation attempts. The remediation process should include thorough testing of patched versions to ensure that the buffer overflow condition has been properly addressed without introducing regressions in functionality.