Source: cve@mitre.org
Directory traversal vulnerability in Mike Spice My Calendar before 1.5 allows remote attackers to write arbitrary files via .. (dot dot) sequences in a URL.
Mike Spice My Calendar versions prior to 1.5 are vulnerable to a critical directory traversal attack, allowing attackers to write arbitrary files to the server. This vulnerability could lead to complete system compromise, including remote code execution and data exfiltration, by allowing attackers to overwrite critical system files or upload malicious web shells.
Step 1: Crafting the Malicious URL: The attacker constructs a URL containing a malicious payload that includes '..'(dot dot) sequences to traverse the directory structure. This payload is designed to target a specific file path outside the intended web root.
Step 2: Payload Delivery: The attacker sends the crafted URL to the vulnerable My Calendar application. The URL is typically accessed through a web browser or automated script.
Step 3: Server-Side Processing: The My Calendar application receives the malicious URL and attempts to process the request, including the file path specified in the URL. Due to the lack of input validation, the application interprets the '..'(dot dot) sequences as valid path components.
Step 4: File Writing: The application, using the manipulated path, attempts to write the attacker-supplied data (e.g., a web shell) to the specified location on the server's file system. This could include overwriting existing files or creating new ones.
Step 5: Exploitation: If successful, the attacker can then access the uploaded file (e.g., a web shell) and execute arbitrary commands on the server, leading to complete system compromise.
The vulnerability stems from insufficient input validation in the My Calendar application. Specifically, the application fails to properly sanitize user-supplied input within a URL parameter used to specify file paths. This allows an attacker to inject '..'(dot dot) sequences into the URL, effectively manipulating the file path and navigating outside the intended directory. The application then writes data to the attacker-specified location without proper checks, leading to arbitrary file creation and potential overwriting of critical system files. The root cause is a lack of path traversal prevention mechanisms, such as input validation and output encoding, allowing for path manipulation and file system access outside the intended scope.
This vulnerability is a classic example of a web application security flaw and could be exploited by a wide range of threat actors. While no specific APT groups are directly linked to this CVE, the ease of exploitation makes it attractive to both opportunistic attackers and more sophisticated groups. The vulnerability's potential for remote code execution makes it a high-value target. This vulnerability is not listed on the CISA KEV at this time, but given its potential impact, it could be considered for inclusion.
Monitor web server logs for suspicious URL patterns containing '..'(dot dot) sequences, especially those targeting file write operations.
Implement file integrity monitoring (FIM) to detect unauthorized changes to critical system files.
Analyze network traffic for unusual HTTP requests that include potentially malicious payloads.
Use intrusion detection/prevention systems (IDS/IPS) with signatures designed to detect directory traversal attempts.
Review web server access logs for requests that result in 400 or 500 errors, which may indicate exploitation attempts.
Upgrade to My Calendar version 1.5 or later, which should include a fix for this vulnerability.
Implement robust input validation to sanitize all user-supplied input, ensuring that file paths are properly validated and do not contain '..'(dot dot) sequences.
Restrict file write operations to the minimum necessary and ensure that files are written to a secure location within the web root.
Implement output encoding to prevent the injection of malicious code into files.
Use a web application firewall (WAF) to filter out malicious requests, including those containing directory traversal attempts.
Regularly scan the system for vulnerabilities using automated tools.
Apply the principle of least privilege to the web server's file system access.
Consider using a Content Delivery Network (CDN) to mitigate the impact of a successful attack.