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Why does CPU temperature matter for security? How to monitor and control CPU temperature?

The CPU or Central processing unit is the brain of the computer. It consists of processors which process the instructions received from users or applications and produce the desired output. A CPU is inside every device, such as our smartphones, washing machines, dishwashers, gaming consoles.

I believe this is something that even a novice user of a PC or Laptop is aware of.

If you remember that last time, when you touch your laptop and it was „hot as hell“, then most likely the cause of that was exaclty overheat of the CPU.

The speed at which instructions are processed is determined by the clock speed of the CPU. Higher clock speed indicates that the CPU is operating at high speed. While performing complex tasks, processing continuous instructions, and using programs that require intensive system resources, the clock speed increases, which raises the temperature.

This article will discuss how higher temperature indicates a possible security breach and what risks are? Alongside, the methods to monitor and possible measures to control the high temperatures will be highlighted.


Does a higher CPU temperature indicate a security breach?

Yes, frequent higher temperatures do indicate a possible security attack or breach. System administrators or standard users should keep a close watch on their CPU's temperature. If you observe frequent high temperatures, then it rings an alarm for a compromise.

Below are some of the possible situations which can occur due to high temperatures:

Malware Infection

Malware analysts and reverse engineers believe that frequent high temperatures are one of the side effects of a malware infection.

They reached this conclusion after profound analysis of different types of viruses and malware. Suppose you experience a lag in the normal functioning or the system freeze. In that case, the CPU fan is flaring out louder than usual, even at an idle system state. There are greater chances of your system being infected with malware.

It could be just a nuisance programm that makes the system use intensive CPU resources, which increases clock speed. As a result, overheating occurs. But we can‘t exclude infection with more dangerous malware, which can cause even physical damage to you system. One should immediately check for a suspicious program or application running in the background in such a scenario. Additionally, check the recently downloaded files and perform a system scan.

Common Malware Types. Among malware, adware, spyware, viruses, worms and trojans

Image Source – enterprise.comodo.com

Denial-of-Service (DoS) Attack

DoS is a type of Cyber-attack in which the services or resources of the system, server, website, or program are made unavailable to legitimate users.

The CPU's heat dissipation functions are program-dependent. The operating system contains these programs.

These pre-configured programs can control the fan, voltage, and frequency of the CPU. Thus, malicious code can be written to manipulate this program. Additionally, some software can be used to put a CPU under thermal stress and raise the temperature.

DoS - Thermal Choking

This phenomenon appears when the CPU gets overheated, and the cooling system fails to dissipate heat. As an opposing reaction, the CPU reduces clock speed to produce less heat. This results in loss of performance and is called Thermal Choking.

If attackers manage to disable the fans and cooling system, it will raise the temp above the average level. This puts a system under extreme thermal stress resulting in thermal choking.

Security researchers have observed that such attacks degrade the performance of a system by 50%. This is an effective DoS attack because 50% of system resources become unavailable to the intended user.

DoS - Reset

Thermal stress can raise the temperature much higher than an average level.

This extreme high temp activates the fail-safe and resets the computer. If the virus is configured to get triggered at reboot, the system will continuously reset (so-called logic bomb). The disruption this attack causes includes corrupting the file system as a result of hard drive damage.

This is also the implementation of a Denial-of-Service attack because the system cannot be operated normally.

Denial-of-service and Data Integrity-DVS

DVS is a short-hand for Dynamic Voltage and Frequency Scaling. This allows the CPU to operates at a low-power state when the load on the CPU is light. It also allows the CPU to scale up to a high-performance state when running CPU-intensive programs. This functionality is controlled by an OS program.

The ability to control DVS settings through software is the primary security risk.

Any malicious code can be used to alter the settings. If the frequency is reduced, it directly affects the system performance. As soon as the voltage reaches a level far below the CPU's minimum requirement, different system errors such as system freeze, internal compiler error, program crash appear. It is all due to the activities mentioned above, thermal stress increases.

This halts the normal functioning of the system.

How DDoS attack can lead to overheated device

System Damage

Frequent over-heating and thermal stress significantly decrease the lifetime of a system. Excess temperatures also contribute to several failure mechanisms. The CPU chip can also be potentially damaged or rendered useless.

Data loss along with substantial financial loss can occur at the Industrial level and in facilities where expensive supercomputers are being used. This is a potential threat to these systems and facilities because vulnerabilities associated with high temperatures and thermal stress are often neglected.

The impact of high temperature on CPU and security risks have been discussed above. Now, it is time to educate the novice user about monitoring and control methods.

How can I monitor and control over-heating?

If any CPU-intensive programs or processes are running in parallel, CPU temperature rises significantly, which is a logical consequence.

Higher temperature is not abnormal as components do get heated up. This is a temporary effect, and it gets back to normal. Over-heating of the components occurs when the temperature exceeds the factory-preset level. If the temperature remains high too often and over-heating becomes an everyday routine, this is something to worry about.

Monitoring Methods

You can monitor CPU temp manually or through different free tools available for this purpose. Manually, in Windows, the temperature can be checked in BIOS/UEFI menu. You will have to stop current activities and restart the system to enter into BIOS settings. This is a cumbersome task and indeed an old school.

Now, we have several efficient and easy-to-use tools monitoring free tools available.

Below listed are some of the recommended tools.

1. AIDA64

This tool is compatible with Windows, IOS, and Android. It displays detailed diagnostics about the system components. Moreover, the result of diagnostics can be exported in a CSV, HTML, or XML file.

The one major drawback is it has a bit complicated UI.

Main working window of AIDA64 Extreme, where many sensor data is indicated

Image Source – aida64.com

2. Speccy

This tool runs on Windows only.

It shows information related to the system hardware and software and provides the real-time temperature of the CPU, a quick summary of installed hardware, and helps troubleshoot the problems.

Speccy provide many real-time data using very clear and easy to operate UI

Image Source – speccy.com

3. Coretemp

It is a simple tool to check the CPU temp of an x86 based processor.

It is an efficient tool that supports all manufacturers such as AMD, Intel, etc. One of the main features of this tool is that it reads directly from a digital thermal sensor inside the CPU.

Moreover, it provides the flexibility for developers to add new features as per requirements.

Core Temp provides data directly from internal sensors with some additional info

Image Source – coretemp.com

4. HWMonitor

This program is designed to read the system sensors like temperature, fan speed, voltages, etc. It provides the ability to manually edit sensor labels, generates logging graphs as bitmap files.

Users can check CPU utilization and bandwidth. Amazingly this monitoring tool has a built-in firewall that can detect restricted port access.

Users will find extensive amount of data from sensors

Image Source – hwmonitor.com

5. Real Temp

It is specially designed for all Intel processors.

It has an added feature that allows to individually adjust the temperature of each core of the CPU. It is rapid, accurate, and precise. We can also keep track of minimum and maximum temperatures.

Most compact indication of temperature per core for CPU as well as checking their  thermal status

 Image Source – realtemp.com

Optimal Temperature

The location and external environmental conditions affect the CPU temperature. Therefore, it is mandatory to familiarize yourself with your system's normal range considering all the early mentioned conditions.

Secondly, every processor type has a different normal range. To know the normal range of your processor, visit the manufacturer's website, search for the specific type, and read the documentation.

Here are some rough ideal temperature estimated, irrespective of the CPU model and types.

  • Under low usage, the temp should be between 30 to 50 °C (86 to 122 °F).
  • When running CPU-intensive programs: up to 95 °C (up to 203 °F).
  • At any time, the maximum temperature should not exceed 100 °C (212 °F).

However, the latest processors can endure high thermal stress, and their break-points are set high, even above 103 °C.

High temp not only affects the processor but also has a consequential impact on other individual components. The periodic tear-down of individual components is also the consequence of over-heating.

Tips to control high temperatures

You do not have to lower the CPU temp every time manually.

When the temp exceeds a factor-preset normal range, this indicates thermal stress. The thermal control circuit inside the CPU begins lowering the clock speed. Hence, all the activities being performed by the processor are halted. This disruption is for two microseconds only. This process continues until the optimal low temperature is achieved.

However, there are times when the CPU fails to lower the temperature itself. There can be many reasons for this, but the following are the major ones.

  • The foremost is improper airflow. Improper airflow is mainly due to fan malfunction or choking. If the surrounding area is dusty, the fan can also pull that dust which also causes fan choking.
    Do watch-out fans, clean regularly, and replace the faulty ones. An efficient and clean set of fans in the PC case is vital for maintaining positive airflow.
    Positive airflow prevents over-heating.
  • Thermal paste is applied on the top of the CPU since it helps transfer the heat away from the CPU into the heat sink. This gets dried up after some time resulting in increased temp. We usually neglect this cause of over-heating.
    It is recommended to replace the old layer twice or thrice a year.
  • Periodically, check for malware and viruses in the system and perform regular scans by using antivirus software. Malware free system has a considerably lower temperature than the one infected with malware.
  • External environmental conditions have a significant impact on temperature. If your environment is too hot, then minimize the usage. Otherwise, place your system at a place with adequate cooling arrangements.
  • CPU overclocking is also a significant contributor to high temps. If you have overclocked your CPU to improve the performance, then make adequate cooling arrangements. Overclocking increases clock speed that results in increased temperature.
  • Laptop users are recommended to use laptop stands. As the laptop fan is at its base, the solid and flat surface of the stand helps to improve airflow. Hence, preventing the laptop from suffocation.
    It also helps in setting a comfortable use position and posture.


All in all, by implementing above mentioned tips, the over-heating issue can be reduced significantly.

Overheating can cause individual components to malfunction. Therefore, these measures will save you from the replacement cost of features or systems in the worst case. Moreover, user experience and system performance can also be improved.

Some of the above-listed potential risks, vulnerabilities, and threats associated with high CPU temperature are not considered until now. That is why these threats are a potential risk due to their novelty. Such attacks are difficult to recognize because research is still being conducted on similar security vulnerabilities.

It will take some years until we have concrete case studies and attack patterns.

If you know any other reasons for overheated CPU and other hardware components, let me know in the comments below, and I will also check them.

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