CVE-2017-15079 in Smush Image Compression
Summary
by MITRE
The Smush Image Compression and Optimization plugin before 2.7.6 for WordPress allows directory traversal.
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Analysis
by VulDB Data Team • 11/22/2019
The CVE-2017-15079 vulnerability affects the Smush Image Compression and Optimization plugin for WordPress, specifically versions prior to 2.7.6, introducing a critical directory traversal flaw that can be exploited by malicious actors to access unauthorized files on the affected system. This vulnerability stems from insufficient input validation within the plugin's file handling mechanisms, allowing attackers to manipulate file paths and potentially access sensitive data stored outside the intended directories. The issue manifests when the plugin processes image optimization requests, where user-supplied parameters are not properly sanitized before being used in file system operations, creating an attack vector that directly violates fundamental security principles of input validation and access control.
The technical implementation of this directory traversal vulnerability enables attackers to navigate beyond the intended file system boundaries through crafted requests that manipulate path traversal sequences such as "../" or similar constructs. When the vulnerable plugin processes these manipulated parameters, it fails to properly validate or sanitize the input before using it in file operations, resulting in unauthorized file access. This flaw directly maps to CWE-22, which defines the weakness of Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal or directory traversal attacks. The vulnerability can be exploited to access configuration files, database credentials, wp-config.php, or other sensitive files that should remain protected from unauthorized access, making it particularly dangerous in web application environments where such files often contain critical authentication and operational information.
The operational impact of this vulnerability extends beyond simple file access, as it provides attackers with potential pathways to escalate privileges and gain deeper system access. An attacker who successfully exploits this directory traversal vulnerability can potentially access not only image files but also configuration files that may contain database connection strings, API keys, or other sensitive information that could lead to further compromise of the WordPress installation. The attack surface is particularly concerning given that WordPress plugins often have elevated privileges and access to various system resources. This vulnerability can be leveraged as part of a broader attack chain, potentially enabling attackers to execute additional exploits or maintain persistent access to the compromised system, aligning with ATT&CK technique T1059 for Command and Scripting Interpreter and T1078 for Valid Accounts, where the initial compromise could lead to further lateral movement and privilege escalation activities.
The recommended mitigation strategy involves immediate upgrading of the Smush plugin to version 2.7.6 or later, which includes proper input validation and sanitization mechanisms to prevent directory traversal attacks. Organizations should also implement additional security measures such as restricting file permissions on WordPress installations, implementing web application firewalls that can detect and block suspicious path traversal patterns, and conducting regular security audits of installed plugins and themes. System administrators should ensure that the WordPress core, themes, and plugins are regularly updated to address known vulnerabilities, as this particular flaw represents a common class of security issues that have been documented in numerous other applications and frameworks. The vulnerability underscores the importance of proper input validation and access control mechanisms in web applications, particularly those handling file system operations, and serves as a reminder of the critical need for comprehensive security testing and regular vulnerability assessments in content management systems.