CVE-2018-11726 in Libmobi
Summary
by MITRE
The mobi_decode_font_resource function in util.c in Libmobi 0.3 allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact via a crafted mobi file.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-11726 resides within the mobi_decode_font_resource function located in the util.c file of Libmobi version 0.3. This library serves as a critical component for processing mobi format files, which are commonly used for digital publishing and e-book distribution. The flaw manifests as a heap-based buffer overflow that occurs when processing specially crafted mobi files, presenting a significant security risk to systems that rely on this library for file processing operations.
The technical implementation of this vulnerability stems from inadequate input validation within the mobi_decode_font_resource function. When the library encounters a malformed mobi file containing crafted malicious data, the function fails to properly bounds-check buffer allocations, leading to memory corruption through heap overflow conditions. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which represents a common class of memory safety issues that can lead to arbitrary code execution or system instability. The vulnerability is particularly dangerous because it can be triggered remotely through the processing of maliciously constructed mobi files without requiring any special privileges or user interaction.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as attackers can potentially leverage the heap overflow to achieve more severe consequences including arbitrary code execution or system compromise. Systems that process mobi files from untrusted sources, such as e-book readers, digital publishing platforms, or content management systems, become vulnerable to remote exploitation. The vulnerability affects the broader ecosystem of applications that depend on Libmobi for mobi file handling, creating a cascading risk across multiple software implementations that utilize this library. The attack surface is particularly concerning given the widespread use of mobi format files in digital publishing and mobile reading applications.
Mitigation strategies for CVE-2018-11726 should prioritize immediate patching of affected Libmobi versions to address the buffer overflow vulnerability. Organizations should implement robust input validation measures and sanitize all mobi files before processing them through the library. The implementation of memory safety techniques such as stack canaries, address space layout randomization, and heap corruption detection mechanisms can provide additional defense-in-depth layers. Security monitoring should focus on detecting unusual file processing patterns and potential exploitation attempts targeting mobi file handlers. This vulnerability aligns with ATT&CK technique T1203, Exploitation for Client Execution, as it represents a remote code execution vector that can be exploited through client-side file processing operations. Organizations should also consider implementing network segmentation and access controls to limit exposure of systems that process mobi files, particularly those that handle untrusted content from external sources.