Source: security@qnapsecurity.com.tw
An allocation of resources without limits or throttling 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 prevent other systems, applications, or processes from accessing the same type of resource. We have already fixed the vulnerability in the following versions: QTS 5.2.7.3256 build 20250913 and later QuTS hero h5.2.7.3256 build 20250913 and later QuTS hero h5.3.1.3250 build 20250912 and later
QNAP NAS devices are vulnerable to a critical resource exhaustion attack. An attacker with administrator privileges can denial-of-service (DoS) the device by consuming a critical resource, rendering it unusable for legitimate users and applications. This vulnerability requires immediate patching to prevent significant data loss and service disruption.
Step 1: Administrator Account Compromise: The attacker must first obtain administrator-level credentials. This could be achieved through various means, such as brute-forcing weak passwords, exploiting other vulnerabilities, or social engineering. Step 2: Identify Target Resource: The attacker identifies the specific resource that is vulnerable to exhaustion (e.g., network connections, memory allocation, CPU usage). Step 3: Craft Malicious Request(s): The attacker crafts a malicious request or a sequence of requests designed to consume the target resource at an excessive rate. Step 4: Submit Malicious Request(s): The attacker submits the crafted request(s) to the QNAP device, typically through the web interface or other network services. Step 5: Resource Exhaustion: The QNAP device processes the malicious request(s), leading to the rapid consumption of the targeted resource. Step 6: Denial of Service: As the resource is exhausted, the device becomes unresponsive or experiences significant performance degradation, effectively denying service to legitimate users and applications.
The vulnerability stems from a lack of resource limits or throttling within the QNAP operating system. Specifically, the affected code does not properly validate or restrict the allocation of a critical resource (e.g., memory, CPU cycles, network connections). An attacker, upon gaining administrator access, can craft a malicious request or sequence of requests that consume this resource at an unsustainable rate. This leads to resource exhaustion, effectively causing a DoS condition. The root cause is likely a missing or inadequate implementation of resource quotas or rate limiting mechanisms within the affected system components. The absence of these controls allows an attacker to monopolize the resource, preventing legitimate users and processes from accessing it.
Due to the potential impact and the prevalence of QNAP devices, this vulnerability is likely to be targeted by various threat actors, including ransomware groups and state-sponsored actors. The ease of exploitation, once the specific resource is identified, makes it a prime target. CISA KEV: Not currently listed, but likely to be added if exploitation becomes widespread.
Monitor system resource utilization (CPU, memory, network connections) for unusual spikes or sustained high usage, especially after administrator login attempts.
Analyze QNAP device logs for suspicious activity, such as repeated requests from a single IP address or user account.
Implement network intrusion detection systems (IDS) to identify malicious traffic patterns associated with resource exhaustion attacks. Look for unusual request rates or patterns.
Monitor for failed login attempts, which could indicate attempts to compromise administrator accounts.
Review system logs for errors related to resource allocation or denial of service events.
Immediately update QNAP devices to the patched versions: QTS 5.2.7.3256 build 20250913 and later, QuTS hero h5.2.7.3256 build 20250913 and later, and QuTS hero h5.3.1.3250 build 20250912 and later.
Enforce strong passwords and multi-factor authentication (MFA) for all administrator accounts.
Regularly review and audit administrator account privileges.
Implement network segmentation to limit the impact of a potential compromise.
Monitor system logs and network traffic for suspicious activity.
Consider implementing rate limiting and resource quotas on critical services to mitigate the impact of future vulnerabilities.
Disable unnecessary services and features on the QNAP device.
Regularly back up data to ensure business continuity in case of a successful attack.