CVE-2015-5214 in LibreOffice
Summary
by MITRE
LibreOffice before 4.4.6 and 5.x before 5.0.1 and Apache OpenOffice before 4.1.2 allows remote attackers to cause a denial of service (memory corruption and application crash) or execute arbitrary code via an index to a non-existent bookmark in a DOC file.
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Analysis
by VulDB Data Team • 06/26/2022
The vulnerability identified as CVE-2015-5214 represents a critical memory corruption flaw affecting LibreOffice versions prior to 4.4.6 and 5.x versions prior to 5.0.1, alongside Apache OpenOffice versions before 4.1.2. This vulnerability stems from insufficient input validation when processing DOC files containing malformed bookmark references. The flaw manifests when the software attempts to access an index pointing to a non-existent bookmark within the document structure, creating a scenario where memory corruption occurs during the parsing process. Such memory corruption directly impacts the application's stability and security posture, as it can lead to unpredictable behavior ranging from application crashes to potential code execution. The vulnerability is particularly concerning because it can be triggered through simple document manipulation, making it an attractive target for remote exploitation.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where programs access memory locations beyond the intended buffer boundaries. When a DOC file contains an index reference to a non-existent bookmark, the parsing logic fails to properly validate the existence of the referenced element before attempting to access it. This results in the software dereferencing invalid memory pointers, leading to heap corruption. The flaw operates at the document parsing layer, where the application's parser does not adequately implement bounds checking or validation routines for bookmark references. This type of vulnerability falls under the ATT&CK technique T1203, which involves exploitation of software vulnerabilities to gain unauthorized access or execute arbitrary code, and T1059, which encompasses the use of command and scripting interpreters for execution. The memory corruption occurs during the document loading process when the application attempts to resolve cross-references within the document's internal structure.
The operational impact of CVE-2015-5214 extends beyond simple denial of service scenarios to potentially enable remote code execution capabilities. Attackers can craft malicious DOC files that, when opened by vulnerable applications, trigger memory corruption leading to application crashes or more severe consequences. The vulnerability's exploitability is enhanced by the fact that DOC files are commonly used in business environments, making them prime targets for social engineering attacks. Organizations relying on LibreOffice or Apache OpenOffice for document processing face significant risk, as the vulnerability can be exploited through email attachments, document sharing platforms, or any mechanism that allows users to open external DOC files. The potential for privilege escalation exists when the vulnerable applications run with elevated privileges, and the memory corruption can be leveraged to execute arbitrary code within the application's security context, particularly in environments where users open untrusted documents.
Mitigation strategies for CVE-2015-5214 primarily focus on immediate software updates to patched versions of LibreOffice, Apache OpenOffice, and related products. System administrators should prioritize deployment of the vendor-provided security patches that address the bookmark validation logic and implement proper bounds checking mechanisms. Organizations should also consider implementing document filtering policies that restrict the opening of external DOC files, particularly those from untrusted sources, until the patches are deployed. Network-level protections can include content filtering solutions that scan document attachments for suspicious patterns or malformed structures. The implementation of sandboxing techniques for document processing applications provides an additional layer of defense, limiting the potential impact of successful exploitation attempts. Regular security awareness training for end users helps prevent accidental exploitation through social engineering campaigns targeting document opening behaviors. Additionally, monitoring systems should be configured to detect unusual application crash patterns or memory access violations that may indicate exploitation attempts. The vulnerability serves as a reminder of the importance of maintaining current security patches and implementing defense-in-depth strategies to protect against memory corruption vulnerabilities that can lead to serious security consequences.