This is why it is recommended you stick with the official repositories.
These applications are used by many experienced users and should a virus
be introduced many would know real quickly and the problem fixed not
covered over.

How much easer would it be to write a virus, than if the source code was
given to you? Oh wait, I guess it is. Then why has it been so hard for
the sub-world to destroy Linux's rep as being hard to infect? Because
some of the best minds in the world work behind the image to keep it
solid, as well as security is built into the system.

I look at computers as portable safes with Linux having the dead bolts
built into the structure. I see MS Windows as a safe with the dead bolts
exposed on the outside of the box, with a simple bicycle lock keeping
out the honest people. The lock for MS is purchased from outside
companies like AVG and other large names, that have become famous
because Microsoft has no clue how to build in security.

Looking at the two safes side by side, even the casual bystander can see
the holes in one of the systems. Any one that believes that virus
programmers don't work on Linux viruses because there is not enough
market. Have bought the bill of goods the marketers of MS products have
sold them, and are still wearing blinders. Now both safes are only
going to keep the goods safe if you leave the door closed and locked.
For Linux this is done by using safe practices and safe repositories.
For MS Windows, well not so much!

No safe is secure if you don't keep it in your possession.