Why does one scanner detect a virus but another does not?

[shaneViews]

Hello,

 

I saw that lots of times, Like if I am using a scanner it is showing nothing, the system is secure. But If I scan with other antivirus it detects thread. 

[goretsky Supervisor]

Hello,

 

A few reasons, in no particular order:

 

• Anti-malware companies do not all receive the same samples of new malware at the same time.
• Anti-malware companies' researchers might not add detection for them at the same time, i.e., other samples may have higher priority; be easier to add detection for, and so forth.
• False positive alarm (e.g., anti-malware software reports a detection when, in fact, that malware is not present).
• False negative alarm (e.g, anti-malware software has detection, but it's not 100%, and misses an instance of it).

There are other reasons, too, but that's just off the top of my head.

 

Regards,

 

Aryeh Goretsky

[T3X4S]

Most use their own database of bad things, others it might be their heuristic engine - but its like saying - "why does every car maker make a different car?"

If you're wondering if your system is infected, or if you are just doing some checking/updating - you shouldnt even be scanning with the AV software...thats not what its intended for.

Sure it might work, and wont mess anything up, but AV software is meant to keep things out in the 1st place, you need something else to do the scanning, and subsequent removal...use the free malwarebytes.

As far as why do some say its clean, and others flag something - well it could be settings, it could be one includes PUP, others dont care about PUP (Potentially Unwanted Program)
It could be one has a better heuristic engine, one has a more up to date blacklist - or a more accurate blacklist.

The reason could be 1000 things, but ultimately boils down to its why/how some are better than others.