CVE-2017-8104 in MyBB
Summary
by MITRE
In MyBB before 1.8.11, the smilie module allows Directory Traversal via the pathfolder parameter.
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Analysis
by VulDB Data Team • 09/20/2020
The vulnerability identified as CVE-2017-8104 affects MyBB versions prior to 1.8.11 and resides within the smilie module functionality. This directory traversal flaw specifically targets the pathfolder parameter, which is used to specify the directory path where smiley images are stored. The vulnerability represents a critical security weakness that allows unauthorized users to access files and directories beyond the intended scope of the application's file system access controls. The issue stems from insufficient input validation and sanitization within the smilie handling component, where user-supplied pathfolder parameters are directly processed without proper security checks to prevent malicious path manipulation attempts.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious pathfolder parameter containing directory traversal sequences such as ../ or ..\ that bypass the application's intended file access boundaries. This allows the attacker to navigate through the file system hierarchy and potentially access sensitive files that should remain protected from public access. The flaw operates at the application layer and can be exploited through web-based interfaces where the smilie module is utilized, making it particularly dangerous as it can be triggered by users with minimal privileges. The vulnerability falls under the CWE-22 category of Directory Traversal, which is classified as a common weakness in web applications that fail to properly validate file path inputs.
The operational impact of CVE-2017-8104 extends beyond simple information disclosure, as successful exploitation can lead to complete system compromise through access to configuration files, database credentials, application source code, and potentially other sensitive system resources. Attackers can leverage this vulnerability to gather intelligence about the server environment, identify other potential weaknesses, and potentially escalate privileges within the application. The vulnerability can be exploited through various attack vectors including web browser-based interactions, automated scanning tools, and manual exploitation techniques that target the specific pathfolder parameter handling within MyBB's smilie module.
Security mitigations for this vulnerability primarily involve upgrading to MyBB version 1.8.11 or later, which includes proper input validation and sanitization for the pathfolder parameter. Organizations should also implement additional defensive measures such as restricting file system access permissions for the web application, implementing proper input validation at multiple layers, and conducting regular security assessments of web applications to identify similar path traversal vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under the T1083 technique for File and Directory Discovery, highlighting the reconnaissance aspect of exploitation. Additionally, implementing web application firewalls and input validation rules specifically designed to detect and block directory traversal sequences can provide additional protection layers. Organizations should also consider implementing principle of least privilege access controls and regular security patch management processes to prevent similar vulnerabilities from being exploited in their environments.