CVE-2015-6783 in Chrome
Summary
by MITRE
The FindStartOffsetOfFileInZipFile function in crazy_linker_zip.cpp in crazy_linker (aka Crazy Linker) in Android 5.x and 6.x, as used in Google Chrome before 47.0.2526.73, improperly searches for an EOCD record, which allows attackers to bypass a signature-validation requirement via a crafted ZIP archive.
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Analysis
by VulDB Data Team • 11/18/2024
The vulnerability identified as CVE-2015-6783 resides within the crazy_linker component of Android operating systems version 5.x and 6.x, as well as in Google Chrome versions prior to 47.0.2526.73. This flaw specifically affects the FindStartOffsetOfFileInZipFile function located in the crazy_linker_zip.cpp source file, which is part of the Crazy Linker library responsible for dynamic library loading and memory management in Android applications. The issue manifests when the system processes ZIP archives for executable file extraction and validation, creating a critical security gap that could be exploited by malicious actors. The vulnerability stems from improper handling of End of Central Directory (EOCD) record searching mechanisms, which are fundamental components in ZIP file structure validation.
The technical implementation flaw occurs when the FindStartOffsetOfFileInZipFile function attempts to locate the EOCD record within a ZIP archive. This function performs a backward search through the file to identify the correct signature that marks the end of the central directory structure. However, the implementation contains a logic error that fails to properly validate the search results, allowing an attacker to craft a malicious ZIP file where the EOCD record appears at an incorrect location or with invalid characteristics. This improper validation bypasses the signature verification mechanism that should ensure only legitimate executable files are loaded into memory. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, as the flawed search algorithm can be manipulated to produce incorrect offset calculations that lead to execution of unauthorized code.
From an operational perspective, this vulnerability creates a significant attack surface for privilege escalation and code execution scenarios. When an Android application or Chrome browser processes a maliciously crafted ZIP file, the system's signature validation mechanism becomes ineffective, potentially allowing attackers to inject and execute arbitrary code within the application's memory space. The impact is particularly severe because it affects core system components that handle dynamic library loading, making it possible for attackers to bypass security controls designed to prevent unauthorized code execution. This vulnerability can be exploited in various contexts including phishing attacks, malicious file downloads, and supply chain attacks where attackers craft ZIP archives designed to exploit this specific flaw.
The attack vector for CVE-2015-6783 aligns with techniques described in the MITRE ATT&CK framework under T1059 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation. The vulnerability enables attackers to perform code injection attacks by manipulating ZIP file structures, potentially leading to full system compromise when combined with other exploitation techniques. Security researchers have noted that this flaw demonstrates poor input validation practices and inadequate error handling in archive processing components, which are common patterns in software security vulnerabilities. Organizations implementing security controls should consider this vulnerability when assessing their mobile application security posture, particularly in environments where users may encounter untrusted ZIP files or when using outdated versions of Chrome browser.
Mitigation strategies for CVE-2015-6783 include immediate patching of affected Android versions and Google Chrome installations to version 47.0.2526.73 or later, where the signature validation has been properly implemented. System administrators should also implement network-level controls to scan and filter potentially malicious ZIP files before they reach end users, particularly in enterprise environments. Additional defensive measures include disabling automatic ZIP file extraction in browsers and applications, implementing strict file type validation, and monitoring for unusual patterns in file processing activities. The vulnerability serves as a reminder of the importance of proper input validation and secure coding practices in security-critical components, particularly those handling file format parsing and validation operations.