CVE-2017-17528 in ScummVM
Summary
by MITRE
backends/platform/sdl/posix/posix.cpp in ScummVM 1.9.0 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 • 01/18/2023
The vulnerability identified as CVE-2017-17528 resides within the ScummVM multimedia engine version 1.9.0, specifically in the posix.cpp file located in the backends/platform/sdl/posix directory. This issue represents a critical security flaw that stems from inadequate input validation mechanisms within the application's handling of environment variables. The vulnerability occurs when ScummVM attempts to launch an external browser application using the BROWSER environment variable, which is commonly used by applications to determine which web browser to open when displaying external content. The flaw manifests as a lack of proper sanitization and validation of strings passed through this environment variable, creating an avenue for malicious exploitation.
The technical nature of this vulnerability places it squarely within the domain of command injection attacks, specifically categorized under CWE-78 as "Improper Neutralization of Special Elements used in an OS Command." The flaw allows attackers to inject malicious arguments into the command execution flow when the application launches the browser specified in the BROWSER environment variable. This occurs because the application directly incorporates user-supplied or environment-provided strings into system calls without adequate sanitization or escaping mechanisms. When a crafted URL is processed through this vulnerable code path, the malicious input can be interpreted as additional command-line arguments rather than simple URL parameters, potentially enabling arbitrary command execution or unintended browser behavior.
The operational impact of this vulnerability extends beyond simple browser launching functionality, as it provides attackers with a potential foothold for more extensive system compromise. Remote attackers who can influence the BROWSER environment variable or manipulate the URL handling mechanism can execute arbitrary commands on the target system with the privileges of the user running ScummVM. This represents a significant risk in environments where ScummVM might be used in conjunction with untrusted content or when the application is run with elevated privileges. The vulnerability is particularly concerning because it can be exploited through web-based attack vectors, making it accessible to attackers who might not have direct access to the system but can influence the application's execution context through network-based means.
Mitigation strategies for CVE-2017-17528 should focus on implementing proper input validation and sanitization mechanisms within the ScummVM codebase. The most effective approach involves ensuring that any strings extracted from environment variables or user-provided inputs are properly escaped and validated before being incorporated into system commands. This aligns with the principle of least privilege and secure coding practices recommended by the OWASP Top Ten and MITRE ATT&CK framework, particularly in the context of command execution and environment variable handling. System administrators should also consider implementing environment variable restrictions and monitoring for unusual command execution patterns. Additionally, the vulnerability highlights the importance of proper application sandboxing and input validation in multimedia applications that interact with external system resources, emphasizing the need for robust security controls in cross-platform software development practices.