CVE-2017-12919 in libfpx
Summary
by MITRE
Heap-based buffer overflow in OLEStream::WriteVT_LPSTR in olestrm.cpp in libfpx 1.3.1_p6 allows remote attackers to cause a denial of service via a crafted fpx image.
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Analysis
by VulDB Data Team • 11/10/2019
The vulnerability CVE-2017-12919 represents a heap-based buffer overflow flaw within the libfpx library version 1.3.1_p6, specifically within the OLEStream::WriteVT_LPSTR function located in the olestrm.cpp source file. This issue arises from inadequate input validation and memory management when processing crafted fpx image files, creating a condition where attacker-controlled data can overwrite adjacent memory regions in the heap allocation space. The vulnerability manifests during the parsing of file format structures that utilize the VT_LPSTR data type, which is commonly employed in OLE (Object Linking and Embedding) compound document formats for storing null-terminated strings. The flaw occurs when the library attempts to write string data to memory locations without proper bounds checking, allowing an attacker to manipulate the write operation to exceed allocated buffer boundaries. This particular vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a critical memory safety issue that can lead to arbitrary code execution or system instability. The attack vector requires remote exploitation through the delivery of a maliciously crafted fpx image file, making it particularly dangerous in web-based environments where users might unknowingly download and process such files. The vulnerability impacts systems that utilize libfpx for processing fpx image files, including various multimedia applications, document viewers, and content management systems that support this specific image format. When exploited, the buffer overflow can result in denial of service conditions where the application crashes or becomes unresponsive, but more critically, could potentially allow for remote code execution if proper exploit mitigations are not in place. The flaw demonstrates the importance of proper input validation in file format parsers, as the issue stems from the library's failure to validate string length parameters before performing memory writes. This vulnerability aligns with ATT&CK technique T1203, which involves exploitation of software vulnerabilities in applications to achieve remote code execution or denial of service outcomes. The specific nature of the flaw indicates that it may be susceptible to exploitation through the manipulation of file format structures that are commonly encountered in multimedia processing pipelines. The vulnerability highlights the inherent risks associated with complex file format parsing libraries that must handle various data types and structures while maintaining memory safety. Systems utilizing libfpx for image processing should be considered at risk until proper patches are applied, as the buffer overflow can potentially be leveraged to cause system instability or, in more sophisticated exploitation scenarios, achieve arbitrary code execution within the context of the vulnerable application. The impact extends beyond simple denial of service as the heap corruption can lead to unpredictable application behavior, data loss, or potentially allow attackers to gain additional privileges if the vulnerable application operates with elevated permissions. Security practitioners should prioritize patching systems that rely on libfpx, particularly those exposed to untrusted file inputs through web interfaces or email attachments, as the vulnerability provides a clear path for remote attackers to compromise system availability and potentially execute malicious code. The flaw demonstrates the critical importance of validating all input data in multimedia processing libraries, especially when dealing with compound document formats that may contain nested structures and variable-length data elements that require careful memory management to prevent buffer overflows.