CVE-2018-6639 in MathType
Summary
by MITRE
An out-of-bounds write (Remote Code Execution) issue was discovered in Design Science MathType 6.9c. A size used by memmove is read from the input file. This is fixed in 6.9d.
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Analysis
by VulDB Data Team • 01/09/2020
The vulnerability identified as CVE-2018-6639 represents a critical out-of-bounds write condition that can lead to remote code execution within Design Science MathType version 6.9c. This flaw exists in the handling of input file data during memory operations, specifically involving the memmove function which is responsible for copying memory blocks. The vulnerability arises from improper validation of size parameters read from external input files, creating a scenario where maliciously crafted data can cause memory corruption beyond intended boundaries.
The technical implementation of this vulnerability stems from the application's failure to properly validate or sanitize the size parameter used in memmove operations. When MathType processes a specially crafted input file, it reads a size value from the file that determines how much data to copy using memmove. This size value, when improperly validated, can exceed the bounds of allocated memory regions, resulting in an out-of-bounds write condition. The CWE-787 entry specifically addresses out-of-bounds write vulnerabilities, which are classified as a critical threat vector in software security. This flaw directly aligns with the ATT&CK technique T1059.007 for command and script interpreter execution, as successful exploitation could enable adversaries to execute arbitrary code on affected systems.
The operational impact of CVE-2018-6639 extends beyond simple data corruption, as it provides a potential pathway for remote code execution attacks. An attacker could craft a malicious input file that, when opened by a victim using MathType 6.9c, would trigger the vulnerable code path and allow arbitrary code execution with the privileges of the affected user. This vulnerability is particularly concerning in enterprise environments where MathType is commonly used for document editing and mathematical content creation. The attack surface expands significantly when considering that users may unknowingly open malicious files from email attachments, shared network drives, or web downloads, making this a high-severity threat vector that requires immediate remediation.
The fix implemented in MathType version 6.9d addresses this vulnerability through proper input validation and bounds checking of size parameters before memmove operations are executed. This remediation aligns with industry best practices for preventing memory corruption vulnerabilities and follows the principle of least privilege in memory management operations. Organizations should prioritize updating to version 6.9d or later to mitigate this risk, as the vulnerability can be exploited remotely without user interaction once the malicious file is opened. Security teams should also implement network monitoring to detect potential exploitation attempts and consider deploying application whitelisting policies to restrict execution of untrusted MathType files. The vulnerability serves as a reminder of the critical importance of proper memory management and input validation in preventing remote code execution exploits, particularly in widely used productivity software applications.