Hello, 

I recently came across a zip file attachment containing a malware exe that is 
not being banned by amavis. 
The amavis configuration allows for zip but not exe files. 


If amavis is configured to ban zip files, amavis does recognize the file as zip 
and bans it. 


If the exe is unzipped first then sent, amavis does recognize the file as exe 
and bans it. 


I checked and amavis is using the internal decoder for .zip files, which is 
able to manually unarchive the file. 
I also tried to set the decoder to use 7z for zip, but the exe was still not 
banned. 


Oddly, the maillog shows no warnings or errors. All other zip files containging 
exe's are properly banned. 


This is using amavisd-new-2.6.6 running on Ubuntu 10.04.4 LTS x64. 


The malware contained in the zip is dyreza, more info about the file can be 
found here. 


https://www.virustotal.com/en/file/d60e70b89a9c8179bb7486d8a447d3100cfcff598746eaf9bffa15589e5eb9e8/analysis/
 







Regards 

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