Marshall initially left Villa in June, but has now been brought back to the club by Kevin MacDonald to offer back-up to Friedel and Guzan.
The 35-year-old did not make a first-team appearance for Villa last term and trained with Colchester during pre-season.
A return to Villa Park had been discussed in recent weeks and Marshall is happy to have taken up the opportunity to work with MacDonald again.
"It's been in the pipeline for the last three weeks that it potentially could happen," Marshall told the club's official website.
"I was released in the summer with the possibility of coming back. I am absolutely delighted it has been done and I am very thankful for Kevin MacDonald for bringing me back because I have got a good relationship with Kev.
"I worked very well with him in the reserves with the young lads last season and he sees it as an opportunity to get Elliott (Parish) out on loan and get him some match games.
"There is still the cover having myself here in case anything happens with either of the Brads."