Security of Sandisk Secure Access Manager on Yuuwaa.com

I have a Sandisk Cruzer Blade 4Gb USB stick with Sandisk Secure Access Manager on it.

This operates satisfactorily and appears to leave no insecure trace of a file that has been opened read-only after it has been closed.  The software also offers the use of secure space on Yuuwaa.com as a backup, which in principle is very useful and is very easy to operate. However, what is not made clear is that when opening files from Yuuwaa.com, temporary files are created which are not deleted when they are closed. Thus if e.g. you go into an internet cafe on the other side of the world, access a file from your vault on Yuuwaa.com , a copy of that file will be left on the PC you have been using, which is potentially highly compromising if you open a file containing sensitive information. My experience of my old CruzerLock was that most public/institutional PCs would not allow it to operate because it involved installing software, which I assume will be the same for Sandisk Secure Access Manager on a USB drive, tempting one to use Yuuwaa.com in that sort of situation where you have online access, which is potentially compromising.

Sandisk customer support replied top me individually:

‘I understand that you are using Secure Access on your SanDisk Cruzer flash drive. You would like to know however what happens with the temporary file which is created when downloading a file from the Cruzer or from YuuWaa.com and if this would be vulnerable to an attack by a trojan or similar malware.
We can understand your concern indeed regarding this, however the temporary file which is being created, gets deleted. So far we have never encountered any any malware responding to this temporary file.’

I replied to this as follows:

Thanks for your reply. Unfortunately you appear to be wrong about Yuuwaa.com. If you download a file from the ONLINE edition of Sandisk Secure Access Manager on Yuuwaa.com using Opera or Mozilla, after closing the file, it is still possible to find a copy, under its own name, in eg Opera Temp. It has to be deleted manually. As far as I can  see Yuuwaa.com is fine as an emergency backup, but not for routine accessing of sensitive data.

Milo