Source: security@qnapsecurity.com.tw
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. If a remote attacker gains a user account, they can then exploit the vulnerability to launch a denial-of-service (DoS) attack. We have already fixed the vulnerability in the following versions: QTS 5.2.6.3195 build 20250715 and later QuTS hero h5.2.6.3195 build 20250715 and later
QNAP NAS devices are vulnerable to a denial-of-service (DoS) attack due to a NULL pointer dereference. A remote attacker with user account access can trigger this vulnerability, potentially causing significant disruption to data availability and network services. Immediate patching is crucial to mitigate this risk.
Step 1: Account Compromise: The attacker gains access to a valid user account on the QNAP device. This could be through credential stuffing, phishing, or exploiting another vulnerability.
Step 2: Input Crafting: The attacker crafts a malicious input, likely a network request or data payload, designed to trigger the vulnerability.
Step 3: Pointer Manipulation: The crafted input is processed by a vulnerable function within the QNAP operating system. This function uses the attacker-controlled input to set a pointer to NULL.
Step 4: Dereference: The vulnerable function attempts to dereference the NULL pointer, trying to access the memory location it points to.
Step 5: Crash and DoS: The dereference of the NULL pointer causes the affected process to crash, leading to a denial-of-service condition. The NAS device may become unresponsive or experience service disruptions.
The vulnerability stems from a failure to properly validate a pointer before dereferencing it. Specifically, a function within the QNAP operating system likely receives input from a user, potentially through a network request. This input is then used to determine the value of a pointer. If the input is crafted maliciously, it can cause the pointer to be set to NULL. Subsequently, the function attempts to access the memory location pointed to by this NULL pointer, resulting in a NULL pointer dereference. This leads to a crash of the affected process, causing a DoS condition. The root cause is a lack of input validation, leading to an unhandled edge case where a NULL pointer is used. This could be due to a missing check before accessing a data structure or a failure to handle an unexpected input value. The specific function and input vector are not disclosed in the provided information, but the vulnerability is likely triggered by a crafted network request or user input.
While no specific APTs or malware are directly linked to this vulnerability based on the provided information, any threat actor targeting NAS devices could potentially leverage this vulnerability. The lack of public information suggests this is a new vulnerability. CISA KEV status: Not Listed.
Monitor system logs for frequent process crashes or unexpected service restarts, especially those related to core QNAP system processes.
Analyze network traffic for unusual patterns or suspicious requests originating from the compromised user account.
Implement file integrity monitoring to detect any unauthorized modifications to system files.
Review system logs for error messages indicating NULL pointer dereferences or segmentation faults.
Monitor for excessive CPU or memory usage, which could indicate an attempt to exploit the vulnerability.
Immediately update QNAP devices to the patched versions: QTS 5.2.6.3195 build 20250715 and later, and QuTS hero h5.2.6.3195 build 20250715 and later.
Enforce strong password policies and multi-factor authentication (MFA) for all user accounts.
Review user account privileges and restrict access to only the necessary resources.
Regularly back up data to ensure business continuity in case of a successful attack.
Implement a web application firewall (WAF) to filter malicious traffic.
Segment the network to limit the impact of a potential compromise.
Enable automatic security updates to ensure timely patching of future vulnerabilities.