Title: Command injection vulnerability in Ruby Gem sprout 0.7.246

Download: http://rubygems.org/gems/sprout, http://projectsprouts.org/

Vulnerability:

The unpack_zip() function contains the following code:

sprout-0.7.246/lib/sprout/archive_unpacker.rb

60           zip_dir = File.expand_path(File.dirname(zip_file))
61           zip_name = File.basename(zip_file)
62           output = File.expand_path(dir)
63           # puts ">> zip_dir: #{zip_dir} zip_name: #{zip_name} output: #{output}    "     
64           %x(cd #{zip_dir};unzip #{zip_name} -d #{output})


If the attacker can control zip_dir, zip_name or output then they can possibly 
execute shell commands by injecting shell meta characters as input. 


PoC:

For example: filename;id;.zip

I contacted the developer a few weeks ago but received no response.

Thanks!
Larry W. Cashdollar
@_larry0