CVE-2015-2970 in PHP Simple Oekaki BBS
Summary
by MITRE
index.php in LEMON-S PHP Simple Oekaki BBS before 1.21 allows remote attackers to delete arbitrary files via the oekakis parameter.
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Analysis
by VulDB Data Team • 07/04/2017
The vulnerability identified as CVE-2015-2970 affects LEMON-S PHP Simple Oekaki BBS versions prior to 1.21, representing a critical file deletion flaw that enables remote attackers to execute arbitrary file removal operations. This vulnerability resides within the index.php script and specifically targets the oekakis parameter handling mechanism. The flaw demonstrates characteristics consistent with CWE-22, known as "Improper Limitation of a Pathname to a Restricted Directory," where input validation fails to properly restrict file access paths, allowing malicious actors to manipulate the system's file operations.
The technical exploitation of this vulnerability occurs through manipulation of the oekakis parameter in the index.php script, which processes user input without adequate sanitization or validation. Attackers can craft malicious requests that bypass normal file access controls and directly target system files for deletion, potentially compromising the entire web application and underlying server infrastructure. The vulnerability represents a directory traversal issue where the application fails to properly validate or sanitize user-supplied input before using it in file operations, creating an attack surface that allows for arbitrary file system manipulation.
Operational impact of this vulnerability extends beyond simple file deletion, as it provides attackers with the capability to remove critical application files, configuration data, or even system files that could lead to complete application compromise or service disruption. The remote nature of the attack means that exploitation can occur from any location without requiring physical access or local privileges, making it particularly dangerous in web-facing environments. This vulnerability aligns with ATT&CK technique T1059.007, "Command and Scripting Interpreter: PowerShell," and T1486, "Data Encrypted for Impact," as it enables attackers to manipulate the system's file structure and potentially escalate privileges through the removal of critical components.
Mitigation strategies for CVE-2015-2970 should prioritize immediate patching of the LEMON-S PHP Simple Oekaki BBS to version 1.21 or later, which contains the necessary input validation fixes. Organizations should implement proper parameter validation and sanitization for all user inputs, particularly those used in file operations, adhering to secure coding practices that prevent directory traversal attacks. Additionally, implementing proper access controls and file permission settings can limit the damage that can be caused by such vulnerabilities. The fix should include input validation that prevents special characters or sequences that could manipulate file paths, along with proper error handling that does not expose system file structures to attackers. Security monitoring should be enhanced to detect unusual file deletion patterns and unauthorized access attempts to web application directories.