CVE-2008-4939 in apertium
Summary
by MITRE
apertium 3.0.7 allows local users to overwrite arbitrary files via a symlink attack on (a) /tmp/#####.lex.cc, (b) /tmp/#####.deformat.l, (c) /tmp/#####.reformat.l, (d) /tmp/#####docxorig, (e) /tmp/#####docxsalida.zip, (f) /tmp/#####xlsxembed, (g) /tmp/#####xlsxorig, and (h) /tmp/#####xslxsalida.zip temporary files, related to the (1) apertium-gen-deformat, (2) apertium-gen-reformat, and (3) apertium scripts.
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Analysis
by VulDB Data Team • 10/13/2018
The vulnerability identified as CVE-2008-4939 represents a critical file system security flaw affecting the apertium 3.0.7 translation toolkit. This issue stems from improper handling of temporary files during the translation process, creating a dangerous symlink attack vector that allows local users to manipulate the system's file structure. The vulnerability specifically targets multiple temporary file locations within the /tmp directory, each serving distinct purposes in the translation workflow including lexical processing, document formatting, and file conversion operations.
The technical implementation of this vulnerability exploits the predictable naming patterns of temporary files used by apertium during its processing operations. The system creates temporary files with specific naming conventions such as /tmp/#####.lex.cc, /tmp/#####.deformat.l, and similar patterns for various document formats including docx and xlsx files. When these temporary files are created without proper security checks, attackers can establish symbolic links with the same names in the /tmp directory before the legitimate processes attempt to create them. This race condition allows attackers to redirect the output of the translation processes to arbitrary locations on the file system, potentially overwriting critical system files or injecting malicious content.
The operational impact of this vulnerability extends beyond simple file overwrites, as it can be leveraged to escalate privileges and compromise the integrity of the entire translation environment. Attackers exploiting this weakness can manipulate the translation pipeline to overwrite system binaries, configuration files, or even create backdoors within the translation framework. The vulnerability affects three core scripts: apertium-gen-deformat, apertium-gen-reformat, and the main apertium script, indicating a systemic issue in how temporary file operations are handled across the entire toolchain. This widespread impact suggests that the vulnerability is not isolated to a single component but represents a fundamental flaw in the application's temporary file management strategy.
The security implications align with CWE-377: Insecure Temporary Files and CWE-378: Poor File Permissions, as the vulnerability demonstrates both improper temporary file creation and insufficient access controls. From an attack framework perspective, this vulnerability maps to techniques described in the MITRE ATT&CK framework under T1059.001 (Command and Scripting Interpreter) and T1548.001 (Abuse Elevation Control Mechanism) where attackers can leverage file system weaknesses to execute malicious code. The vulnerability particularly affects systems where apertium is used in multi-user environments or where local users might have access to the translation tool but not necessarily to system-level privileges. Organizations should implement immediate mitigations including ensuring proper file permissions, using secure temporary file creation methods, and implementing proper input validation to prevent symlink attacks. The vulnerability underscores the critical importance of secure temporary file handling in software development practices and highlights the need for proper security testing of file system operations in translation and document processing applications.