Source: security@qnapsecurity.com.tw
A path traversal vulnerability has been reported to affect several product versions. If a local attacker gains a user account, they can then exploit the vulnerability to read the contents of unexpected files or system data. We have already fixed the vulnerability in the following versions: Qfinder Pro Mac 7.13.0 and later Qsync for Mac 5.1.5 and later QVPN Device Client for Mac 2.2.8 and later
A critical path traversal vulnerability allows a local attacker with user account access to read sensitive files and system data. This vulnerability, affecting multiple versions of QNAP software, could lead to data exfiltration and system compromise. Immediate patching and security audits are crucial to mitigate the risk.
Step 1: Account Compromise: The attacker must first obtain a valid user account on the target system. This could be achieved through various means, such as social engineering, credential stuffing, or exploiting other vulnerabilities.
Step 2: Path Traversal Payload Construction: The attacker crafts a malicious file path containing path traversal sequences (e.g., ../../../etc/passwd). This path is designed to navigate outside the intended directory.
Step 3: Payload Delivery: The attacker submits the malicious path to the vulnerable application through a specific input field or function. The exact method of delivery depends on the affected product and the vulnerable functionality.
Step 4: Vulnerable Function Execution: The application processes the attacker-supplied path without proper validation or sanitization. It then uses the malicious path to access a file.
Step 5: File Read and Data Exfiltration: The application reads the contents of the file specified by the attacker's path. The attacker can then potentially exfiltrate the contents of the file, such as sensitive system data or configuration files.
The vulnerability stems from improper input validation and sanitization of user-supplied file paths. Specifically, the affected software fails to adequately validate or sanitize user-controlled input used in file operations, such as file reads. This allows an attacker to craft a malicious path containing path traversal sequences (e.g., ../) to access files outside of the intended directory. The root cause is likely a missing or inadequate check on the user-provided path before it is used in a file system operation. This could be due to a lack of input validation, improper use of path manipulation functions, or a combination of both. The absence of proper access control checks further exacerbates the issue, allowing unauthorized access to sensitive files.
While no specific APT groups are directly linked to this vulnerability at this time, the nature of the vulnerability makes it attractive to various threat actors. APTs known for targeting network attached storage (NAS) devices and those seeking to gain initial access or escalate privileges would be likely candidates. This vulnerability could be used as part of a larger attack chain. CISA KEV status: Not applicable at this time.
Monitor file access logs for suspicious file access patterns, especially attempts to read system files (e.g., /etc/passwd, /etc/shadow, configuration files).
Analyze application logs for unusual file path inputs, particularly those containing path traversal sequences (e.g., ../).
Implement file integrity monitoring to detect unauthorized modifications to critical system files.
Network traffic analysis: Look for unusual data exfiltration patterns, such as large file transfers or data transfers to unexpected destinations.
Endpoint Detection and Response (EDR) systems can be configured to alert on suspicious file access attempts and process executions.
Immediately update to the patched versions of the affected products: Qfinder Pro Mac 7.13.0 and later, Qsync for Mac 5.1.5 and later, and QVPN Device Client for Mac 2.2.8 and later.
Implement robust input validation and sanitization to prevent path traversal attacks. This includes validating file paths against a whitelist of allowed characters and directories.
Enforce least privilege principles, restricting user access to only the necessary files and directories.
Regularly audit and review file access permissions.
Implement a Web Application Firewall (WAF) to filter malicious requests.
Conduct a thorough security audit of the affected software to identify and remediate any other potential vulnerabilities.
Enable two-factor authentication (2FA) for all user accounts to mitigate the risk of compromised credentials.