Avast generally doesn’t do anything automatically, it has recommended default settings, which you the user can change, e.g. set it to Repair as the first option, send to chest as second option and Ask for third option, etc.

So I rather doubt it will do anything other than what the original action was, e.g. send to chest, it won’t take any action within the chest unless you initiate it from within the chest.

  • Only true virus infection can be repaired, e.g. when a virus infects a file it adds a small part to it, provided that virus is one that avast’s embedded Repair routines covers, then it may be possible to repair the file to its uninfected state.

  • However, for the most part so called viruses, trojans (adware/spyware/malware, etc.) can’t be repaired because the complete content of the file is malicious.

There is nothing to stop you changing the file system shields Expert Settings, Actions as I mentioned above.

Legitimate System files (not just files in the system folders) are a different ball game any way as their removal to the chest or otherwise could hurt the system. We have seen this in the past across many different AVs. 

Avast! does have some additional checks and there are some important system files that avast won't move even if infected as they still keep the system functioning. This at least gives the user a chance to manually clean/replace the infected file with a known clean one (almost certainly will require help to do that, as we have seen in the viruses and worms forum) without bricking the system.