CVE-2018-10120 in LibreOffice
Summary
by MITRE
The SwCTBWrapper::Read function in sw/source/filter/ww8/ww8toolbar.cxx in LibreOffice before 5.4.6.1 and 6.x before 6.0.2.1 does not validate a customizations index, which allows remote attackers to cause a denial of service (heap-based buffer overflow with write access) or possibly have unspecified other impact via a crafted document.
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Analysis
by VulDB Data Team • 02/28/2023
The vulnerability identified as CVE-2018-10120 represents a critical heap-based buffer overflow flaw within the SwCTBWrapper::Read function of LibreOffice's ww8toolbar.cxx module. This issue affects LibreOffice versions prior to 5.4.6.1 and 6.x versions before 6.0.2.1, where the software fails to properly validate a customizations index parameter during document parsing operations. The flaw resides in the filter component responsible for processing ww8 document formats, specifically within the toolbar customization handling mechanism that processes external document data.
The technical implementation of this vulnerability stems from inadequate input validation within the SwCTBWrapper::Read function which processes toolbar customization data embedded within ww8 documents. When a maliciously crafted document is processed, the function attempts to read a customizations index without proper bounds checking or validation of the index value against allocated memory boundaries. This allows attackers to manipulate the index value to point beyond the allocated buffer space, resulting in heap corruption through write operations that exceed the intended memory allocation. The vulnerability manifests as a heap-based buffer overflow with write access capabilities, enabling potential exploitation for denial of service conditions or more severe impacts.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the heap corruption could potentially enable arbitrary code execution or data manipulation. Remote attackers can craft malicious documents that trigger this vulnerability when opened by vulnerable LibreOffice installations, making it particularly dangerous in environments where users frequently open external documents. The vulnerability affects both the 5.x and 6.x release lines of LibreOffice, indicating a widespread impact across multiple versions. The write access aspect of the buffer overflow specifically aligns with CWE-121, heap-based buffer overflow conditions that allow memory corruption through unauthorized write operations.
This vulnerability maps to several ATT&CK techniques including T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, as it enables remote code execution through document manipulation. The flaw also relates to T1190, Exploit Public-Facing Application, since it affects a component that processes external documents accessible through standard office applications. Organizations using LibreOffice in enterprise environments face significant risk as this vulnerability can be exploited through social engineering campaigns targeting document attachments. The memory corruption aspects of this vulnerability also align with ATT&CK's T1068, Exploitation for Privilege Escalation, if successful exploitation leads to privilege escalation opportunities.
Mitigation strategies for CVE-2018-10120 focus primarily on upgrading to patched versions of LibreOffice, specifically versions 5.4.6.1 or 6.0.2.1 and later. System administrators should implement strict document filtering policies to prevent opening of untrusted documents, particularly those from external sources. Network-level protections can include content filtering solutions that scan document attachments for suspicious patterns. Additionally, users should be trained to avoid opening documents from unknown or untrusted sources, and organizations should maintain regular patch management procedures to ensure timely application of security updates. The vulnerability highlights the importance of input validation in document processing libraries and demonstrates the critical need for robust memory safety mechanisms in office suite applications.