CVE-2018-7289 in Armadito
Summary
by MITRE
An issue was discovered in armadito-windows-driver/src/communication.c in Armadito 0.12.7.2. Malware with filenames containing pure UTF-16 characters can bypass detection. The user-mode service will fail to open the file for scanning after the conversion is done from Unicode to ANSI. This happens because characters that cannot be converted from Unicode are replaced with '?' characters.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2018-7289 resides within the Armadito antivirus solution's Windows driver component, specifically in the communication module located at armadito-windows-driver/src/communication.c. This flaw represents a significant bypass mechanism that allows malicious software to evade detection by exploiting character encoding conversion processes within the antivirus scanning infrastructure. The vulnerability manifests when malware files are named with pure UTF-16 characters, which creates a scenario where the system's file handling mechanism fails to properly process these filenames during the scanning process.
The technical root cause of this vulnerability stems from the improper handling of Unicode to ANSI character set conversion within the user-mode service component. When the system attempts to scan files with UTF-16 encoded filenames, the conversion process encounters characters that cannot be accurately represented in the ANSI character set. During this conversion, the system replaces non-convertible Unicode characters with '?' characters, effectively altering the filename and creating a mismatch between the expected and actual file identification. This conversion failure occurs at the communication layer between the kernel-mode driver and user-mode service, creating a gap in the antivirus's detection capabilities.
The operational impact of this vulnerability is substantial as it provides attackers with a direct method to bypass antivirus protection without requiring sophisticated evasion techniques or exploit development. Malware authors can simply name their malicious files with UTF-16 characters that will be converted to '?' characters, causing the antivirus service to fail opening and scanning these files. This vulnerability operates at the file system level and affects the core scanning functionality, making it particularly dangerous as it can be exploited across various attack vectors including email attachments, downloaded executables, and removable media. The flaw essentially creates a blind spot in the antivirus detection system where files with specific naming conventions can slip through undetected.
This vulnerability aligns with CWE-174, which describes the weakness of "Double Encoding" or improper handling of character encodings, and can be categorized under ATT&CK technique T1059.001 for command and scripting interpreter. The vulnerability represents a classic case of encoding conversion failure that can be exploited to create false positives or false negatives in security systems. Organizations relying on Armadito antivirus solutions would be particularly vulnerable to targeted attacks where threat actors specifically craft malware with UTF-16 filenames to evade detection. The impact extends beyond simple evasion as it demonstrates a fundamental flaw in the system's ability to handle international character sets properly, potentially exposing systems to other encoding-related vulnerabilities.
Mitigation strategies should focus on implementing proper character encoding validation throughout the file handling pipeline, ensuring that all filename conversions maintain integrity and do not introduce false representations. Organizations should update to patched versions of Armadito antivirus where the encoding conversion logic has been corrected to properly handle UTF-16 characters without substitution. System administrators should also implement additional monitoring for unusual filename patterns and consider implementing supplementary detection mechanisms that can identify potential encoding-based evasion attempts. The fix should address the specific conversion process in the communication module to preserve the original filename representation during scanning operations, ensuring that the antivirus system maintains consistent and accurate file identification throughout the entire scanning process.