CVE-2017-17531 in Global
Summary
by MITRE
gozilla.c in GNU GLOBAL 4.8.6 does not validate strings before launching the program specified by the BROWSER environment variable, which might allow remote attackers to conduct argument-injection attacks via a crafted URL.
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Analysis
by VulDB Data Team • 12/15/2019
The vulnerability identified as CVE-2017-17531 resides within the gozilla.c component of GNU GLOBAL version 4.8.6, representing a critical security flaw that undermines the integrity of environment variable handling. This issue manifests when the application processes user-supplied input through the BROWSER environment variable without proper sanitization or validation mechanisms. The flaw specifically affects the program's execution flow when handling crafted URLs, creating an avenue for malicious actors to inject arbitrary command arguments. The vulnerability stems from insufficient input validation practices that fail to properly sanitize string inputs before they are utilized in system command execution contexts.
The technical exploitation of this vulnerability follows a classic argument injection pattern where attacker-controlled data is appended to command-line arguments without proper escaping or encoding. When GNU GLOBAL processes a crafted URL containing malicious input, the gozilla.c module directly incorporates this unvalidated data into the BROWSER environment variable execution chain. This creates a command injection scenario where arbitrary commands can be executed with the privileges of the user running the GNU GLOBAL application. The vulnerability's classification aligns with CWE-77 and CWE-78 within the Common Weakness Enumeration framework, specifically addressing improper neutralization of special elements used in OS commands and command injection vulnerabilities. From an operational perspective, this flaw represents a severe risk to systems where GNU GLOBAL is deployed with elevated privileges, as it could enable remote code execution capabilities.
The impact of this vulnerability extends beyond simple command injection to encompass broader system compromise possibilities. Remote attackers can leverage this flaw to execute arbitrary code on vulnerable systems, potentially leading to complete system takeover. The attack surface is particularly concerning in web environments where GNU GLOBAL might be used for code browsing or navigation purposes, as users might inadvertently encounter malicious URLs. This vulnerability operates under the ATT&CK framework's command and control categories, specifically mapping to techniques involving command injection and remote code execution. The exploitation requires minimal prerequisites, making it particularly dangerous as it can be triggered through simple web navigation or URL handling without requiring complex attack chains. Organizations using GNU GLOBAL in production environments face significant risk if this vulnerability remains unpatched, as it provides attackers with a straightforward path to system compromise.
Mitigation strategies for CVE-2017-17531 should prioritize immediate patch application to the GNU GLOBAL software, as version 4.8.7 and later releases contain the necessary fixes for this vulnerability. System administrators should also implement restrictive environment variable handling policies, ensuring that the BROWSER environment variable is not populated with user-controllable input. Additional protective measures include implementing input validation at multiple layers, utilizing proper command execution libraries that automatically escape special characters, and monitoring for suspicious command execution patterns. Network-level controls such as web application firewalls can help detect and block malicious URL patterns, while regular security audits should verify that environment variable handling follows secure coding practices. The vulnerability serves as a reminder of the critical importance of input validation in system components that interact with environment variables, particularly in applications that execute external programs based on user input. Organizations should also consider implementing principle of least privilege models to limit the impact of potential exploitation, ensuring that GNU GLOBAL applications run with minimal required permissions to reduce potential damage from successful attacks.