CVE-2018-11433 in Libmobi
Summary
by MITRE
The mobi_get_kf8boundary_seqnumber function in util.c in Libmobi 0.3 allows remote attackers to cause information disclosure (heap-based buffer over-read) via a crafted mobi file.
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Analysis
by VulDB Data Team • 02/09/2020
The vulnerability identified as CVE-2018-11433 represents a critical heap-based buffer over-read flaw within the Libmobi 0.3 library, specifically within the mobi_get_kf8boundary_seqnumber function located in util.c. This issue arises from inadequate input validation and memory boundary checking when processing specially crafted mobi files, creating a significant security risk for systems that utilize this library for mobi document handling. The vulnerability classifies under CWE-125 as an out-of-bounds read, which occurs when an application reads memory beyond the allocated buffer boundaries, potentially exposing sensitive data from adjacent memory locations.
The technical exploitation of this vulnerability involves remote attackers constructing malicious mobi files that trigger the buffer over-read condition when the mobi_get_kf8boundary_seqnumber function processes the malformed input. During execution, the function fails to properly validate the size or structure of the input data, allowing an attacker to manipulate the parsing logic to read beyond the intended buffer limits. This over-read behavior can expose confidential information stored in adjacent memory regions, including but not limited to stack canaries, return addresses, cryptographic keys, or other sensitive application data that may be present in the heap memory adjacent to the vulnerable buffer.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable more sophisticated attacks when combined with other exploitation techniques. Systems processing mobi documents through the affected Libmobi library become vulnerable to data leakage that could compromise user privacy or system security. The vulnerability affects any application or service that relies on Libmobi 0.3 for mobi file processing, including e-book readers, document conversion tools, and content management systems that handle mobi formatted files. Attackers could leverage this vulnerability to extract sensitive information from memory, potentially leading to credential theft, system compromise, or further exploitation opportunities that align with ATT&CK technique T1005 for data from local system.
Mitigation strategies for CVE-2018-11433 should prioritize immediate library updates to versions that address the buffer over-read condition through proper input validation and memory boundary checks. System administrators should implement strict file validation processes for all mobi documents before processing, including content scanning and integrity verification mechanisms. The fix typically involves implementing bounds checking within the mobi_get_kf8boundary_seqnumber function to ensure that all buffer accesses remain within allocated memory boundaries. Additionally, deploying runtime protections such as address space layout randomization and stack canaries can help mitigate potential exploitation attempts, though the primary remediation remains updating to a patched version of Libmobi that properly handles input validation and memory management. Organizations should also consider implementing network-based intrusion detection systems to monitor for suspicious mobi file patterns that may indicate exploitation attempts.