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This is somewhat related to this question but at a less serious level - one that causes frustration rather than permanent damage.

From programs like CoreTemp and Speedfan, it is clear that there are ways to read the critical temperature and voltage information from a system. Is there any means of (maliciously) writing parameters into the same monitoring systems so that the BIOS (or whatever is responsible) could be fooled into shutting a system down believing it was dangerously over-voltage or over-temperature? If so, are there any viruses known to operate this way?

I ask because I have a system (ASUS A6U laptop) which was having problems that appeared to be either a virus or a thermal shutdown issue. The essential problem was a strong tendency to fail to boot into Windows XP, which usually occurred immediately after an error reported by lsass.exe (a frequent target of viruses). But moments later the system would always suddenly shut down in a way suggestive of thermal issues. Still, the system would run fine in BIOS for long periods of time, or go through the Windows setup process to a reasonably predictable point, and both suggested the issue had to be dependent on software to some degree.

Interestingly, after restoring the laptop to factory settings on the boot partition (but not reformatting a data partition), it worked fine for a couple of days, lending further weight to the virus/software issue hypothesis. But then it reverted to the previous behaviour. And in the lead up to having boot problems again, it had started to report very strange temperatures through the ASUS NB Probe software.

So I'd like to understand how voltage and temperature are (typically) monitored (are sensors internal or external to CPU; does it happen in CPU, BIOS or operating system; are there read-write parameters; etc) so that I can rule in or out the possibility of virus activity.

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In theory, something could intercept readings from the board / CPU and misreport them, although there would be very limited usefulness. A Virus, after all wants to be undetected. That way it can spread. I also know of no virus that does that. The thermostats are also very limited in their reliability and accuracy.

If a virus is at all involved, you have

  • Usage habit problems to get 2 so quickly
  • Accessed something on your data drive that was infected

If we look past the temporary fix, I would be more inclined to think something else is going on. The fans would go crazy, and a siren sound should come from the system speaker (These are controlled at a lower level than the OS and therefor an OS level virus) if it were a thermal even and a virus intercepted the readings from the operating system.

Depending on the age of the laptop, it may be something more serious. I would contact ASUS if you still have any level of warranty, otherwise I would do a tear-down and visually inspect the motherboard and any add-on cards and go through thorough troubleshooting.

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Thanks - not sure it quite answers my question, but it's useful. Do you know of any useful troubleshooting guide for temperature-related issues? On the surface, temperature is the issue... but I'm just not sure I can trust the temperatures being reported. Clearly it is possible to change the temperature reported to the user, but is it possible to change the temperature that the CPU/BIOS responds to that would lead to throttling or shutdown? That's what I really want to know :-) – omatai Apr 6 '13 at 3:22
No. That is independent of the Operating System where you would catch a virus. Maybe in the future when all EEPROM is replaced with easily over-writable something elses... – AthomSfere Apr 6 '13 at 3:25
OK - so if an actual thermal shutdown or thermal throttling occurs, then you are saying it is "real" as far as the CPU/BIOS is concerned? Which is it? Does the CPU protect itself, or the BIOS protect the CPU? I'm not convinced the temperatures are real... so if you are saying it cannot be a software fault, it must be a hardware issue - bad sensor, bad heatsink connection, etc. – omatai Apr 6 '13 at 3:29

More and more motherboard makers have software utilities to modify these settings in realtime. For example "AI Suite" from ASUS can do it. How well are the internal workings of this software is protected from hacker, I don't know. However, I imagine it is possible.

Generally, a virus writer wants to use your system for his/her own nefarious plans so causing your system to be unstable or shutdown would be against their own best interests.

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