Security #SBU1

Secure usage of Sup

---

Discovered by joernchen of Phenoelit (http://phenoelit.de)

His report:

Phenoelit Advisory <wir-haben-auch-mal-was-gefunden #0815 +-++->

[ Authors ]
        joernchen       <joernchen () phenoelit de>

        Phenoelit Group (http://www.phenoelit.de)

[ Affected Products ]
        sup <= 0.14.1 (on non Darwin systems)
        sup <= 0.13.2 (on non Darwin systems) 
        http://supmua.org

[ Vendor communication ]
        2013-10-28 Send vulnerability details to sup maintainer
        2013-10-28 Maintainer proposes fix
        2013-10-29 Sup 0.13.2.1 and 0.14.1.1 are released [1]
        2013-10-29 Release of this advisory

[ Description ]

        Observe in sup/lib/sup/message_chunks.rb:

def view_default! path
  ## please see note in write_to_disk on important usage
  ## of quotes to avoid remote command injection.
  case RbConfig::CONFIG['arch']
    when /darwin/
      cmd = "open #{path}"
    else
      cmd = "/usr/bin/run-mailcap --action=view #{ () content_type}:#{path}"
  end
  debug "running: #{cmd.inspect}"
  BufferManager.shell_out(cmd)
  $? == 0
end
   
        Here @content_type is attacker controlled and not further 
        sanitized. By this a forged content type of an email 
        attachment can trigger a command injection.

[ Example ]
        For convenience the email delivering this file serves as an
        example. When viewing this attachment in a vulnerable version
        of sup the content type being  "text/'`id>/tmp/whatsup`'pwn"
        will generate a file "whatsup" in the /tmp directory.

[ Solution ]
        Upgrade to version 0.14.1.1 or 0.13.2.1

[ References ]
        [0] https://github.com/sup-heliotrope/sup/blob/916a354db8eb851bff6ff2e3f2e08727d132a8dc/lib/sup/message_chunks.rb#L175
        [1] http://rubyforge.org/pipermail/sup-talk/2013-October/004996.html

[ end of file ]

Links

http://seclists.org/fulldisclosure/2013/Oct/272