CVE-2014-8146 in Watch
Summary
by MITRE
The resolveImplicitLevels function in common/ubidi.c in the Unicode Bidirectional Algorithm implementation in ICU4C in International Components for Unicode (ICU) before 55.1 does not properly track directionally isolated pieces of text, which allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly execute arbitrary code via crafted text.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability identified as CVE-2014-8146 resides within the Unicode Bidirectional Algorithm implementation in ICU4C, specifically within the resolveImplicitLevels function located in common/ubidi.c. This flaw represents a critical security issue affecting International Components for Unicode versions prior to 55.1, where the implementation fails to properly handle directionally isolated text segments during bidirectional text processing. The Unicode Bidirectional Algorithm is fundamental to correctly displaying text that contains both left-to-right and right-to-left character sequences, such as Arabic and Hebrew text mixed with latin characters, making this vulnerability particularly concerning for internationalized applications.
The technical nature of this vulnerability manifests as a heap-based buffer overflow that occurs when the resolveImplicitLevels function processes crafted text inputs containing directionally isolated pieces. The function's improper tracking mechanism leads to memory corruption when handling complex bidirectional text structures, where isolated text segments are not correctly managed during the algorithm's processing phases. This flaw stems from inadequate bounds checking and memory management within the Unicode bidirectional text handling logic, creating opportunities for attackers to manipulate input data in ways that trigger memory corruption. The vulnerability's classification aligns with CWE-121, heap-based buffer overflow, and represents a classic example of improper input validation leading to memory safety issues.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable remote code execution, making it particularly dangerous for web applications and network services that process user-provided text. Attackers can craft malicious text inputs that, when processed through the affected ICU4C implementation, cause the application to crash or potentially execute arbitrary code with the privileges of the affected process. This makes the vulnerability especially critical for applications serving internationalized content, web browsers, email clients, and any system processing untrusted text input. The vulnerability affects systems where ICU4C is used for text processing, including but not limited to web servers, mobile applications, and enterprise software handling multilingual text.
Mitigation strategies for CVE-2014-8146 primarily involve upgrading to ICU4C version 55.1 or later, which contains the necessary patches addressing the buffer overflow condition in the resolveImplicitLevels function. Organizations should conduct thorough testing of their applications after applying the upgrade to ensure compatibility with the patched implementation. Additionally, input validation measures should be implemented at application layers to sanitize text inputs before processing, though this approach provides only partial protection as the vulnerability exists within the core ICU library. Security monitoring should include detection of unusual memory access patterns and potential buffer overflow attempts when processing text content, with particular attention to bidirectional text handling routines. The vulnerability's presence in widely-used Unicode libraries means that comprehensive vulnerability management programs should include regular updates to ICU4C and related components to maintain protection against similar issues. This vulnerability demonstrates the importance of proper memory management in internationalization libraries and the potential for seemingly benign text processing functions to become attack vectors in complex software systems.