I'm lost. (:

using the following rule

zip:*@domain => block => exe-bin|xml

having an exception SHA-hash for the included vba file

what would happen - think about .... 

even harder - in addition there is an object included in the office file 
(it's an OLE which can contain anything - also executables)

what would happen - think about .... 

>If you looked at the rest of the content

Why should assp look at any "rest" if one bad content is found (Its an 
exception)? and reverse - Why should assp look at any "rest" if one known 
good content is found (Its an exception)?

What should be done, if a signature or certificate is hashed , but not the 
executable itself? What is the relation beween the cert and the executable 
or bad file or good files or not bad files?

It makes no sense to further scan an attachment, if a known good file is 
found - because there is no rule for "what to do" , if "what" is found. 

Your suggestion will lead in to a very very complex attachment definition. 
You would have to specify (exactly) for each SHA-hash, which other content 
is allowed or forbidden at which zip-level (possibly at which folder 
level)

Thomas




Von:    "K Post" <nntp.p...@gmail.com>
An:     "ASSP development mailing list" <assp-test@lists.sourceforge.net>
Datum:  21.01.2019 19:07
Betreff:        Re: [Assp-test] fixed in assp 2.6.4 *SPAM-Evaporator* 
build 19015



We can tell vendors not to send zip files, but we don't have a choice for 
some of the bigger ones that our charity works with.  They won't change, 
not ever.  

I understand about AFC just treating office files as zip files (and that's 
fine).  For those vendors who insist on sending zip files with office 
macro enabled files, if we enable the hash of good vbaproject.bin files at 
level 2, then that zip will be set as good regardless of the rest of the 
content.  What I'm asking is why you wouldn't want to mark that file in 
the zip as good, but still check the other files in the zip?  If you 
looked at the rest of the content, that would cause the zip to get 
rejected if an exe is slipped in or non-approved vba is in another file.  
Wouldn't this be preferable functionality for all?






On Mon, Jan 21, 2019 at 4:26 AM Thomas Eckardt <thomas.ecka...@thockar.com
> wrote:
>Would you consider changing this functionality to consider the other 
files in a compressed file, or at least giving us the option between: 


This is not possible, because ASSP_AFC does not know anything about office 
files. Office files are ZIP files and processed like them.
So a part of an Office file will match at zip-level 1. If the Office file 
is in a ZIP the match will be at zip-level 2. 

>but the remaining files in the compressed file (or the other parts of the 
PDF) will be analyzed and can separately trigger stripping of the 
containing zip (or the PDF). 

All other files in an Office file (ZIP) are remaining fles. If you use the 
hash of a signature file to detect the 'good' exception, the (or any) 
project file would be a remaining file (and possibly blocked). 

 
ASSP_AFC handles both cases - "found a bad file" and "found a well known 
good file" - as an exception. In the first case it stops processing the 
attachment and blocks, in the second case it stops processing and 
delivers. Both without analysing any other (still not processed) part of 
this attachment 
The check for "a well known good file" is done first for all files in a 
complete uncompressed tree, before (for example) the executable detection 
is done for any part of the ZIP. 

There is only one way to be sure a "a well known good file" definition 
can't be (easy) frauded. Restrict the zip-level for parts of office files 
to 1 and for PDF to 0 - and tell the vendors to not zip attachments. 

If you fear, a verdors PC can possibly be hijacked and abused to infect 
attachments without lossing an agreed signature - don't use this feature. 

Thomas 


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