Source: security@qnapsecurity.com.tw
A path traversal vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains an administrator 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: QTS 5.2.8.3332 build 20251128 and later QuTS hero h5.2.8.3321 build 20251117 and later
QNAP NAS devices are vulnerable to a path traversal attack, allowing attackers with administrator privileges to read sensitive system files. This vulnerability could lead to data exfiltration and further compromise of the network. Immediate patching is critical to mitigate this risk.
Step 1: Account Compromise: The attacker must first obtain administrator credentials, likely through phishing, brute-force, or exploitation of another vulnerability.
Step 2: Crafting the Payload: The attacker crafts a malicious path traversal payload containing sequences like ../ to navigate up the directory structure.
Step 3: Payload Delivery: The attacker submits the crafted payload to a vulnerable endpoint on the QNAP device, likely through a web interface or API call.
Step 4: File Access: The vulnerable file handling function processes the malicious path, interpreting the ../ sequences and accessing the attacker-specified files.
Step 5: Data Exfiltration: The attacker reads the contents of the targeted files, which may contain sensitive system information, configuration files, or user data. This data is then exfiltrated.
The vulnerability stems from inadequate input validation and sanitization of user-supplied paths within the QNAP operating system. Specifically, the system fails to properly validate or sanitize user-controlled input used in file operations, allowing an attacker to manipulate the path to access files outside the intended directory. The root cause is likely a missing or insufficient check for path traversal sequences (e.g., ../) within the file access functions. This allows an attacker to craft a malicious path that navigates up the directory structure and accesses restricted files. The lack of proper input validation allows the attacker to bypass security measures and gain unauthorized access to sensitive information. The specific function or logic flaw is likely within the file handling routines that process user-provided file paths, where the system fails to properly sanitize or validate the input, allowing for path traversal.
This vulnerability could be exploited by various threat actors, including those seeking to steal sensitive data or establish a foothold on the network. APT groups known to target NAS devices, such as those focused on data theft or ransomware deployment, are of high concern. Not listed on CISA KEV at this time, but this could change rapidly.
Monitor network traffic for unusual HTTP requests containing path traversal sequences (e.g., ../).
Analyze system logs for suspicious file access attempts, especially those involving unexpected files or directories.
Implement file integrity monitoring to detect unauthorized modifications to critical system files.
Review web server logs for suspicious activity, including requests with unusual parameters or file paths.
Use intrusion detection systems (IDS) and intrusion prevention systems (IPS) with signatures designed to detect path traversal attempts.
Immediately update QNAP devices to the patched versions: QTS 5.2.8.3332 build 20251128 and later, and QuTS hero h5.2.8.3321 build 20251117 and later.
Implement strong password policies and enforce multi-factor authentication (MFA) for all administrator accounts.
Regularly audit user accounts and permissions to ensure least privilege access.
Review and harden the web server configuration to prevent unauthorized access.
Implement a web application firewall (WAF) to filter malicious traffic.
Disable unnecessary services and features on the QNAP devices.
Regularly back up critical data to ensure business continuity in case of a successful attack.