CVE-2013-5178 in Mac OS X
Summary
by MITRE
LaunchServices in Apple Mac OS X before 10.9 does not properly restrict Unicode characters in filenames, which allows context-dependent attackers to spoof file extensions via a crafted character sequence.
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Analysis
by VulDB Data Team • 06/01/2021
The vulnerability identified as CVE-2013-5178 resides within Apple Mac OS X versions prior to 10.9 where the LaunchServices framework fails to adequately sanitize Unicode characters in filenames. This weakness enables malicious actors to manipulate file extension recognition through carefully crafted Unicode sequences that appear visually identical to legitimate extensions while maintaining different underlying character representations. The flaw specifically exploits the system's inability to properly handle Unicode normalization during file type determination processes, creating a vector for deception attacks where users might be tricked into executing malicious files disguised as benign ones.
This vulnerability represents a classic case of Unicode confusion attacks that fall under the broader category of CWE-176 - Improper Handling of Unicode Characters. The technical implementation flaw occurs at the core file system interaction layer where LaunchServices relies on character-by-character comparison rather than proper Unicode normalization before making file type decisions. Attackers can exploit this by creating filenames that contain Unicode characters from different scripts or character sets that visually resemble standard file extensions such as .exe, .pdf, or .doc, but use invisible or nearly invisible Unicode characters that are not immediately apparent to users. The attack mechanism leverages the fact that Mac OS X systems prior to 10.9 did not consistently apply Unicode decomposition or normalization rules when processing file names for extension matching.
The operational impact of this vulnerability extends beyond simple file execution risks to encompass broader security implications for user trust and system integrity. When users encounter files with seemingly legitimate extensions, they may unknowingly execute malicious code, particularly in scenarios where the system's default application association is bypassed or when users are not actively monitoring file properties. This vulnerability particularly affects environments where users frequently download files from untrusted sources or where automated file processing systems rely on extension-based file type detection. The context-dependent nature of the attack means that exploitation requires specific conditions where the target system processes the crafted filenames through the vulnerable LaunchServices framework, typically occurring during file opening, double-clicking, or automated file handling operations.
Mitigation strategies for CVE-2013-5178 should focus on both immediate system updates and operational security enhancements. The primary remediation involves upgrading to Mac OS X 10.9 or later versions where Apple implemented proper Unicode normalization within the LaunchServices framework. Additionally, organizations should implement enhanced file scanning procedures that verify file signatures and content rather than relying solely on file extensions for security decisions. Security controls should include regular system audits to identify and remove potentially malicious files that exploit this vulnerability, along with user education programs that emphasize the importance of verifying file properties beyond just visual appearance. From an ATT&CK framework perspective, this vulnerability maps to techniques involving social engineering and execution through masquerading, where attackers leverage the confusion caused by Unicode characters to bypass traditional security controls. Organizations should also consider implementing application whitelisting policies that restrict execution of unknown file types and maintain robust backup and recovery procedures to address potential compromise scenarios.