Re: File downloads in Opera at known locations

[Josh Tolley <josh () raintreeinc com>]

Rohit Dube wrote:

> Hi,
>  This is just a question. While using opera, I observed that as soon as it
> prompts you for file download, it simultaneously starts the download with
> same file extension in its %USERPROFILE/application data/opera/cache. Even
> if the user afterwards chooses cancel, this temporary file does not get
> deleted. 

There are plenty of vulnerabilities that require you to know the 
location of a file. So if you know the value of %USERPROFILE (which is 
available to things like JScript, isn't it?) and can convince the user 
to download your file, this could probably be exploitable.

I expect Opera's convinced it's not a bug because other browsers seem to 
do the same thing. I haven't done detailed investigation, but both IE 
and Mozilla FireFox seem to begin the download to a temp folder as soon 
as you click the link. I expect it's to make the download take less time 
  from the user's point of view. I've noticed on several occasions that 
whatever progress indicator is used in the browser I'm using, it seems 
to start out not from the beginning, but somewhere in the middle, 
indicating that the browser already began downloading.

Josh Tolley