CVE-2016-7415 in International Components for Unicode
Summary
by MITRE
Stack-based buffer overflow in the Locale class in common/locid.cpp in International Components for Unicode (ICU) through 57.1 for C/C++ allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a long locale string.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-7415 represents a critical stack-based buffer overflow within the International Components for Unicode (ICU) library version 57.1 and earlier. This flaw exists in the Locale class implementation located in the common/locid.cpp file, which forms a fundamental component of ICU's internationalization capabilities. The issue arises when processing locale strings that exceed expected length parameters, creating a condition where arbitrary data can overwrite adjacent memory locations on the stack. Such vulnerabilities are particularly dangerous in applications that rely on ICU for handling internationalized text processing, as they can be exploited to disrupt service availability or potentially execute arbitrary code.
The technical implementation of this buffer overflow stems from inadequate input validation within the Locale class parsing mechanism. When a malformed or excessively long locale string is processed, the code fails to properly bounds-check the input before copying it into a fixed-size stack buffer. This allows attackers to craft specially designed locale identifiers that exceed the allocated buffer space, causing stack corruption that ultimately leads to application instability. The vulnerability manifests through a stack-based buffer overflow condition that can be classified under CWE-121, which specifically addresses stack-based buffer overflow vulnerabilities where insufficient bounds checking permits writing beyond allocated buffer boundaries.
From an operational perspective, this vulnerability creates significant risk for applications that utilize ICU for locale processing, particularly those handling user-provided input or external data sources. Remote attackers can exploit this flaw by submitting a carefully constructed locale string that triggers the buffer overflow condition, resulting in immediate application crashes and denial of service conditions. The potential impact extends beyond simple service disruption, as the stack corruption could potentially be leveraged for more sophisticated attacks depending on the target application's memory layout and security mitigations in place. Applications that process internationalized content, web services handling user preferences, or software systems requiring locale-specific formatting are all at risk.
The mitigation strategies for CVE-2016-7415 primarily focus on immediate remediation through software updates and code-level defensive measures. Organizations should prioritize upgrading to ICU versions 58.0 or later, where the buffer overflow has been addressed through proper input validation and bounds checking mechanisms. Additionally, implementing input sanitization at the application level can provide defense-in-depth measures, including validating locale string lengths before passing them to ICU functions. Security controls should also incorporate runtime protections such as stack canaries, address space layout randomization, and control flow integrity checks to reduce the exploitability of similar vulnerabilities. This vulnerability aligns with ATT&CK technique T1203, which covers legitimate program execution through manipulation of loaded libraries, highlighting the importance of maintaining secure software dependencies and implementing proper input validation controls throughout the application stack.